basics tutorial: output updated (#6267)

* basics tutorial: output updated through gcc

* finished update for basics tutorial

* missed two lines

* doc error fix

1 files changed, 1308 insertions, 813 deletions

diff --git a/lib/spack/docs/tutorial_basics.rst b/lib/spack/docs/tutorial_basics.rst
index 5df4179952..d74159d7f6 100644
--- a/lib/spack/docs/tutorial_basics.rst
+++ b/lib/spack/docs/tutorial_basics.rst
@@ -4,17 +4,17 @@
 Basic Installation Tutorial
 =========================================
 
-This tutorial will guide you through the process of installing software
-using Spack. We will first cover the `spack install` command, focusing on
-the power of the spec syntax and the flexibility it gives to users. We
-will also cover the `spack find` command for viewing installed packages
-and the `spack uninstall` command. Finally, we will touch on how Spack
-manages compilers, especially as it relates to using Spack-built
-compilers within Spack. We will include full output from all of the
-commands demonstrated, although we will frequently call attention to only
-small portions of that output (or merely to the fact that it
-succeeded). The provided output is all from a cluster running Red Hat
-Enterprise Linux.
+This tutorial will guide you through the process of installing
+software using Spack. We will first cover the `spack install` command,
+focusing on the power of the spec syntax and the flexibility it gives
+to users. We will also cover the `spack find` command for viewing
+installed packages and the `spack uninstall` command. Finally, we will
+touch on how Spack manages compilers, especially as it relates to
+using Spack-built compilers within Spack. We will include full output
+from all of the commands demonstrated, although we will frequently
+call attention to only small portions of that output (or merely to the
+fact that it succeeded). The provided output is all from an AWS
+instance running Ubuntu 16.04
 
 .. _basics-tutorial-install:
 
@@ -22,24 +22,31 @@ Enterprise Linux.
 Installing Spack
 ----------------
 
-Spack works out of the box. Simply clone spack and get going.
+Spack works out of the box. Simply clone spack and get going. We will
+clone Spack and immediately checkout the most recent release, v0.11.0.
 
 .. code-block:: console
 
-  $ git clone https://github.com/spack/spack.git
-  Initialized empty Git repository in ~/spack/.git/
-  remote: Counting objects: 47125, done.
-  remote: Compressing objects: 100% (68/68), done.
-  remote: Total 47125 (delta 16), reused 2 (delta 2), pack-reused 47047
-  Receiving objects: 100% (47125/47125), 12.02 MiB | 2.11 MiB/s, done.
-  Resolving deltas: 100% (23044/23044), done.
+  $ git clone https://github.com/spack/spack
+  Cloning into 'spack'...
+  remote: Counting objects: 94561, done.
+  remote: Compressing objects: 100% (121/121), done.
+  remote: Total 94561 (delta 91), reused 121 (delta 48), pack-reused 94368
+  Receiving objects: 100% (94561/94561), 32.44 MiB | 31.88 MiB/s, done.
+  Resolving deltas: 100% (44914/44914), done.
+  Checking connectivity... done.
   $ cd spack
+  $ git checkout releases/v0.11.0
+  Branch releases/v0.11.0 set up to track remote branch releases/v0.11.0 from origin.
+  Switched to a new branch 'releases/v0.11.0'
 
-Then add Spack to your path.
+Next add Spack to your path. Spack has some nice command line
+integration tools, so instead of simply appending to your ``PATH``
+variable, source the spack setup script.  Then add Spack to your path.
 
 .. code-block:: console
 
-  $ export PATH=~/spack/bin:$PATH
+  $ . share/spack/setup-env.sh
 
 You're good to go!
 
@@ -52,10 +59,10 @@ The ``spack list`` command shows available packages.
 .. code-block:: console
 
   $ spack list
-  ==> 1016 packages.
-  abinit                           hwloc                  piranha              r-rjava
-  ack                              hydra                  pixman               r-rjson
-  activeharmony                    hypre                  pkg-config           r-rjsonio
+  ==> 2177 packages.
+  abinit                           libepoxy                               py-html5lib                     r-ncdf4
+  abyss                            libevent                               py-httpbin                      r-network
+  ack                              libevpath                              py-hypothesis                   r-networkd3abinit
   ...
 
 The ``spack list`` command can also take a query string. Spack
@@ -64,11 +71,11 @@ we can view all available python packages.
 
 .. code-block:: console
 
-  $ spack list py
-  ==> 129 packages.
-  py-3to2            py-epydoc          py-nestle         py-pycparser         py-six
-  py-alabaster       py-flake8          py-netcdf         py-pydatalog         py-sncosmo
-  py-argcomplete     py-funcsigs        py-networkx       py-pyelftools        py-snowballstemmer
+  $ spack list py-
+  ==> 356 packages.
+  py-3to2                                py-functools32       py-numpydoc         py-pywavelets
+  py-4suite-xml                          py-future            py-olefile          py-pyyaml
+  py-abipy                               py-futures           py-ont-fast5-api    py-qtawesome
   ...
 
 -------------------
@@ -76,26 +83,50 @@ Installing Packages
 -------------------
 
 Installing a package with Spack is very simple. To install a piece of
-software, simply type ``spack install <package_name>``
+software, simply type ``spack install <package_name>``.
 
 .. code-block:: console
 
-  $ spack install libelf
-  ==> Installing libelf
-  ==> Trying to fetch from ~/spack/var/spack/cache/libelf/libelf-0.8.13.tar.gz
-  curl: (37) Couldn't open file ~/spack/var/spack/cache/libelf/libelf-0.8.13.tar.gz
-  ==> Fetching from ~/spack/var/spack/cache/libelf/libelf-0.8.13.tar.gz failed.
-  ==> Trying to fetch from http://www.mr511.de/software/libelf-0.8.13.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libelf-0.8.13-csrt4qxfkhjgn5xg3zjpkir7xdnszl2a/libelf-0.8.13.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libelf-0.8.13-csrt4qxfkhjgn5xg3zjpkir7xdnszl2a
-  ==> No patches needed for libelf
-  ==> Building libelf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libelf
-    Fetch: 1.21s.  Build: 8.42s.  Total: 9.62s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.13-csrt4qxfkhjgn5xg3zjpkir7xdnszl2a
+  $ spack install zlib
+  ==> Installing zlib
+  ==> Fetching file:///home/ubuntu/becker/buildcache/zlib/zlib-1.2.11.tar.gz
+  curl: (37) Couldn't open file /home/ubuntu/becker/buildcache/zlib/zlib-1.2.11.tar.gz
+  ==> Fetching from file:///home/ubuntu/becker/buildcache/zlib/zlib-1.2.11.tar.gz failed.
+  ==> Fetching http://zlib.net/fossils/zlib-1.2.11.tar.gz
+  ######################################################################## 100.0%
+  ==> Staging archive: /home/ubuntu/test/spack/var/spack/stage/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb/zlib-1.2.11.tar.gz
+  ==> Created stage in /home/ubuntu/test/spack/var/spack/stage/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+  ==> No patches needed for zlib
+  ==> Building zlib [Package]
+  ==> Executing phase: 'install'
+  ==> Successfully installed zlib
+    Fetch: 0.58s.  Build: 1.15s.  Total: 1.73s.
+    [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+
+Spack can install software either from source or from a binary
+cache. Packages in the binary cache are signed with GPG for
+security. For the tutorial we have prepared a binary cache so you
+don't have to wait on slow compilation from source. To be able to
+install from the binary cache, we will need to trust the GPG key that
+the binary cache was prepared with.
 
+.. code-block:: console
+
+  $ spack gpg trust ~/public.key
+  gpg: keybox '/home/ubuntu/test/spack/opt/spack/gpg/pubring.kbx' created
+  gpg: /home/ubuntu/test/spack/opt/spack/gpg/trustdb.gpg: trustdb created
+  gpg: key 3B7C69B2: public key "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" imported
+  gpg: Total number processed: 1
+  gpg:               imported: 1
+
+The AWS instances and Docker images we use for the tutorial already
+have configuration files in place so that Spack knows where to look
+for binary packages (and that's the only change we've made). You'll
+learn more about configuring Spack later in the tutorial, but for now
+you will be able to install the rest of the packages in the tutorial
+from a binary cache by specifying ``spack install --use-cache
+<package_name>``. This will install the binary cached version if it
+exists and fall back on installing from source.
 
 Spack's spec syntax is the interface by which we can request specific
 configurations of the package. The ``%`` sigil is used to specify
@@ -103,18 +134,24 @@ compilers.
 
 .. code-block:: console
 
-  $ spack install libelf %intel
-  ==> Installing libelf
-  ==> Trying to fetch from ~/spack/var/spack/cache/libelf/libelf-0.8.13.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libelf-0.8.13-7wgp32xksatkvw2tbssmehw2t5tnxndj/libelf-0.8.13.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libelf-0.8.13-7wgp32xksatkvw2tbssmehw2t5tnxndj
-  ==> No patches needed for libelf
-  ==> Building libelf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libelf
-    Fetch: 0.09s.  Build: 50.64s.  Total: 50.72s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/intel-16.0.3/libelf-0.8.13-7wgp32xksatkvw2tbssmehw2t5tnxndj
+  $ spack install --use-cache zlib %clang
+  ...
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-4.7-libsigsegv-2.11-eaqxu5mka32jpjif32rttiwebimrr2kb.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-util-macros-1.19.1-milz7fmttmptcic2qdk5cnel7ll5sybr.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing zlib from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/zlib-1.2.11/linux-ubuntu16.04-x86_64-clang-3.8.0-2ubuntu4-zlib-1.2.11-4pt75q7qq6lygf3hgnona4lyc2uwedul.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:05:02 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed zlib from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/zlib-1.2.11-4pt75q7qq6lygf3hgnona4lyc2uwedul
 
 Note that this installation is located separately from the previous
 one. We will discuss this in more detail later, but this is part of what
@@ -122,67 +159,59 @@ allows Spack to support arbitrarily versioned software.
 
 You can check for particular versions before requesting them. We will
 use the ``spack versions`` command to see the available versions, and then
-install a different version of ``libelf``.
+install a different version of ``zlib``.
 
 .. code-block:: console
 
-  $ spack versions libelf
+  $ spack versions zlib
   ==> Safe versions (already checksummed):
-    0.8.13
-    0.8.12
+    1.2.11  1.2.8  1.2.3
   ==> Remote versions (not yet checksummed):
-    0.8.11
-    0.8.10
-    0.8.9
-    0.8.8
-    0.8.7
-    0.8.6
-    0.8.5
-    0.8.4
-    0.8.3
-    0.8.2
-    0.8.0
-    0.7.0
-    0.6.4
-    0.5.2
-
+    1.2.10   1.2.7    1.2.5.1  1.2.4.2  1.2.3.7
+    ...
 
 The ``@`` sigil is used to specify versions, both of packages and of
 compilers.
 
 .. code-block:: console
 
-  $ spack install libelf @0.8.12
-  ==> Installing libelf
-  ==> Trying to fetch from ~/spack/var/spack/cache/libelf/libelf-0.8.12.tar.gz
-  curl: (37) Couldn't open file ~/spack/var/spack/cache/libelf/libelf-0.8.12.tar.gz
-  ==> Fetching from ~/spack/var/spack/cache/libelf/libelf-0.8.12.tar.gz failed.
-  ==> Trying to fetch from http://www.mr511.de/software/libelf-0.8.12.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libelf-0.8.12-ipggckv6i7h44iryzfa4dwdela32a7fy/libelf-0.8.12.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libelf-0.8.12-ipggckv6i7h44iryzfa4dwdela32a7fy
-  ==> No patches needed for libelf
-  ==> Building libelf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libelf
-    Fetch: 1.12s.  Build: 7.88s.  Total: 9.00s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.12-ipggckv6i7h44iryzfa4dwdela32a7fy
-
-
-
-  $ spack install libelf %intel@15.0.4
-  ==> Installing libelf
-  ==> Trying to fetch from ~/spack/var/spack/cache/libelf/libelf-0.8.13.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libelf-0.8.13-w33hrejdyqu2j2gggdswitls2zv6kdsi/libelf-0.8.13.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libelf-0.8.13-w33hrejdyqu2j2gggdswitls2zv6kdsi
-  ==> No patches needed for libelf
-  ==> Building libelf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libelf
-    Fetch: 0.09s.  Build: 55.51s.  Total: 55.60s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/intel-15.0.4/libelf-0.8.13-w33hrejdyqu2j2gggdswitls2zv6kdsi
-
+  $ spack install --use-cache zlib@1.2.8
+  ==> Installing zlib
+  ==> Searching for binary cache of zlib
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-clang-3.8.0-2ubuntu4-zlib-1.2.11-4pt75q7qq6lygf3hgnona4lyc2uwedul.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing zlib from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8/linux-ubuntu16.04-x86_64-gcc-5.4.0-zlib-1.2.8-bkyl5bhuep6fmhuxzkmhqy25qefjcvzc.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:05:03 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed zlib from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8-bkyl5bhuep6fmhuxzkmhqy25qefjcvzc
+
+  $ spack install --use-cache zlib %gcc@4.7
+  ==> Installing zlib
+  ==> Searching for binary cache of zlib
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-zlib-1.2.8-bkyl5bhuep6fmhuxzkmhqy25qefjcvzc.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing zlib from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-4.7/zlib-1.2.11/linux-ubuntu16.04-x86_64-gcc-4.7-zlib-1.2.11-bq2wtdxakpjytk2tjr7qu23i4py2fi2r.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:03:00 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed zlib from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-4.7/zlib-1.2.11-bq2wtdxakpjytk2tjr7qu23i4py2fi2r
 
 The spec syntax also includes compiler flags. Spack accepts
 ``cppflags``, ``cflags``, ``cxxflags``, ``fflags``, ``ldflags``, and
@@ -192,19 +221,24 @@ into the compile line automatically by the Spack compiler wrappers.
 
 .. code-block:: console
 
-  $ spack install libelf @0.8.12 cppflags="-O3"
-  ==> Installing libelf
-  ==> Trying to fetch from ~/spack/var/spack/cache/libelf/libelf-0.8.12.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libelf-0.8.12-vrv2ttbd34xlfoxy4jwt6qsjrcbalmmw/libelf-0.8.12.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libelf-0.8.12-vrv2ttbd34xlfoxy4jwt6qsjrcbalmmw
-  ==> No patches needed for libelf
-  ==> Building libelf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libelf
-    Fetch: 0.04s.  Build: 7.95s.  Total: 7.99s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.12-vrv2ttbd34xlfoxy4jwt6qsjrcbalmmw
-
+  $ spack install --use-cache zlib @1.2.8 cppflags=-O3
+  ==> Installing zlib
+  ==> Searching for binary cache of zlib
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-4.7-zlib-1.2.11-bq2wtdxakpjytk2tjr7qu23i4py2fi2r.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing zlib from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8/linux-ubuntu16.04-x86_64-gcc-5.4.0-zlib-1.2.8-64mns5mvdacqvlashkf7v6lqrxixhmxu.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:03:00 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed zlib from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8-64mns5mvdacqvlashkf7v6lqrxixhmxu
 
 The ``spack find`` command is used to query installed packages. Note that
 some packages appear identical with the default output. The ``-l`` flag
@@ -215,36 +249,32 @@ compiler flags of those packages.
 
   $ spack find
   ==> 5 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  libelf@0.8.12
-  libelf@0.8.12
-  libelf@0.8.13
-
-  -- linux-redhat6-x86_64 / intel@15.0.4 --------------------------
-  libelf@0.8.13
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  zlib@1.2.11
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  libelf@0.8.13
+  -- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
+  zlib@1.2.11
 
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  zlib@1.2.8  zlib@1.2.8  zlib@1.2.11
 
 
   $ spack find -lf
   ==> 5 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  ipggckv libelf@0.8.12%gcc
-
-  vrv2ttb libelf@0.8.12%gcc cppflags="-O3"
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  4pt75q7 zlib@1.2.11%clang
 
-  csrt4qx libelf@0.8.13%gcc
 
+  -- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
+  bq2wtdx zlib@1.2.11%gcc
 
-  -- linux-redhat6-x86_64 / intel@15.0.4 --------------------------
-  w33hrej libelf@0.8.13%intel
 
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  bkyl5bh zlib@1.2.8%gcc
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  7wgp32x libelf@0.8.13%intel
+  64mns5m zlib@1.2.8%gcc cppflags="-O3"
 
+  5nus6kn zlib@1.2.11%gcc
 
 Spack generates a hash for each spec. This hash is a function of the full
 provenance of the package, so any change to the spec affects the
@@ -256,24 +286,25 @@ existing package's hash matches the desired spec.
 
 .. code-block:: console
 
-  $ spack install libdwarf
-  ==> Installing libdwarf
-  ==> libelf is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.13-csrt4qxfkhjgn5xg3zjpkir7xdnszl2a
-  ==> Can not find version 20160507 in url_list
-  ==> Trying to fetch from ~/spack/var/spack/cache/libdwarf/libdwarf-20160507.tar.gz
-  curl: (37) Couldn't open file ~/spack/var/spack/cache/libdwarf/libdwarf-20160507.tar.gz
-  ==> Fetching from ~/spack/var/spack/cache/libdwarf/libdwarf-20160507.tar.gz failed.
-  ==> Trying to fetch from http://www.prevanders.net/libdwarf-20160507.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libdwarf-20160507-yfx6p3g3rkmqvcqbmtb34o6pln7pqvcz/libdwarf-20160507.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libdwarf-20160507-yfx6p3g3rkmqvcqbmtb34o6pln7pqvcz
-  ==> No patches needed for libdwarf
-  ==> Building libdwarf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libdwarf
-    Fetch: 1.56s.  Build: 33.59s.  Total: 35.15s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libdwarf-20160507-yfx6p3g3rkmqvcqbmtb34o6pln7pqvcz
-
+  $ spack install --use-cache openssl
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+  ==> Installing openssl
+  ==> Searching for binary cache of openssl
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-zlib-1.2.8-64mns5mvdacqvlashkf7v6lqrxixhmxu.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing openssl from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k/linux-ubuntu16.04-x86_64-gcc-5.4.0-openssl-1.0.2k-2woov64m3n4gjtnfp722qcyemzf2qtom.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:03:18 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed openssl from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k-2woov64m3n4gjtnfp722qcyemzf2qtom
 
 Dependencies can be explicitly requested using the ``^`` sigil. Note that
 the spec syntax is recursive. Anything we could specify about the
@@ -281,36 +312,43 @@ top-level package, we can also specify about a dependency using ``^``.
 
 .. code-block:: console
 
-  $ spack install libdwarf ^libelf @0.8.12 %intel
-  ==> Installing libdwarf
-  ==> Installing libelf
-  ==> Trying to fetch from ~/spack/var/spack/cache/libelf/libelf-0.8.12.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libelf-0.8.12-4blbe3qxqct3ymrfoxxnxysmybvbxay7/libelf-0.8.12.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libelf-0.8.12-4blbe3qxqct3ymrfoxxnxysmybvbxay7
-  ==> No patches needed for libelf
-  ==> Building libelf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libelf
-    Fetch: 0.04s.  Build: 52.16s.  Total: 52.19s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/intel-16.0.3/libelf-0.8.12-4blbe3qxqct3ymrfoxxnxysmybvbxay7
-  ==> Can not find version 20160507 in url_list
-  ==> Trying to fetch from ~/spack/var/spack/cache/libdwarf/libdwarf-20160507.tar.gz
-  ################################################################################################################################################################################# 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libdwarf-20160507-csruprgucaujkfkrcywhwou7nbeis5fo/libdwarf-20160507.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libdwarf-20160507-csruprgucaujkfkrcywhwou7nbeis5fo
-  ==> No patches needed for libdwarf
-  ==> Building libdwarf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libdwarf
-    Fetch: 0.40s.  Build: 2m 17.29s.  Total: 2m 17.69s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/intel-16.0.3/libdwarf-20160507-csruprgucaujkfkrcywhwou7nbeis5fo
-
+  $ spack install --use-cache openssl ^zlib @1.2.8 %clang
+  ==> Installing zlib
+  ==> Searching for binary cache of zlib
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-openssl-1.0.2k-2woov64m3n4gjtnfp722qcyemzf2qtom.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing zlib from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/zlib-1.2.8/linux-ubuntu16.04-x86_64-clang-3.8.0-2ubuntu4-zlib-1.2.8-i426yu3o6lyau5fv5ljwsajfkqxj5rl5.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:03:06 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed zlib from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/zlib-1.2.8-i426yu3o6lyau5fv5ljwsajfkqxj5rl5
+  ==> Installing openssl
+  ==> Searching for binary cache of openssl
+  ==> Installing openssl from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/openssl-1.0.2k/linux-ubuntu16.04-x86_64-clang-3.8.0-2ubuntu4-openssl-1.0.2k-ufruk7kj2fz3oupuat2jbgc2y7hg37vy.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:03:23 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed openssl from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/openssl-1.0.2k-ufruk7kj2fz3oupuat2jbgc2y7hg37vy
 
 Packages can also be referred to from the command line by their package
 hash. Using the ``spack find -lf`` command earlier we saw that the hash
-of our optimized installation of libelf (``cppflags="-O3"``) began with
-``vrv2ttb``. We can now explicitly build with that package without typing
+of our optimized installation of zlib (``cppflags="-O3"``) began with
+``64mns5m``. We can now explicitly build with that package without typing
 the entire spec, by using the ``/`` sigil to refer to it by hash. As with
 other tools like git, you do not need to specify an *entire* hash on the
 command line.  You can specify just enough digits to identify a hash
@@ -319,21 +357,27 @@ packages share the prefix) then spack will report an error.
 
 .. code-block:: console
 
-  $ spack install libdwarf ^/vrv2ttb
-  ==> Installing libdwarf
-  ==> libelf is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.12-vrv2ttbd34xlfoxy4jwt6qsjrcbalmmw
-  ==> Can not find version 20160507 in url_list
-  ==> Trying to fetch from ~/spack/var/spack/cache/libdwarf/libdwarf-20160507.tar.gz
-  #################################################################################################################################################################################################################################################### 100.0%
-  ==> Staging archive: ~/spack/var/spack/stage/libdwarf-20160507-dtg3tgnp7htccoly26gduqlrgvnwcp5t/libdwarf-20160507.tar.gz
-  ==> Created stage in ~/spack/var/spack/stage/libdwarf-20160507-dtg3tgnp7htccoly26gduqlrgvnwcp5t
-  ==> No patches needed for libdwarf
-  ==> Building libdwarf [Package]
-  ==> Executing phase : 'install'
-  ==> Successfully installed libdwarf
-    Fetch: 0.96s.  Build: 24.03s.  Total: 24.99s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libdwarf-20160507-dtg3tgnp7htccoly26gduqlrgvnwcp5t
-
+  $ spack install --use-cache openssl ^/64mn
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8-64mns5mvdacqvlashkf7v6lqrxixhmxu
+  ==> Installing openssl
+  ==> Searching for binary cache of openssl
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-clang-3.8.0-2ubuntu4-zlib-1.2.8-i426yu3o6lyau5fv5ljwsajfkqxj5rl5.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-clang-3.8.0-2ubuntu4-openssl-1.0.2k-ufruk7kj2fz3oupuat2jbgc2y7hg37vy.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing openssl from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k/linux-ubuntu16.04-x86_64-gcc-5.4.0-openssl-1.0.2k-gyxmhgbam26d7y42omb7xrvkjjgmzwio.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:03:12 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed openssl from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k-gyxmhgbam26d7y42omb7xrvkjjgmzwio
 
 The ``spack find`` command can also take a ``-d`` flag, which can show
 dependency information. Note that each package has a top-level entry,
@@ -343,104 +387,198 @@ even if it also appears as a dependency.
 
   $ spack find -ldf
   ==> 9 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  dtg3tgn    libdwarf@20160507%gcc
-  vrv2ttb        ^libelf@0.8.12%gcc cppflags="-O3"
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  ufruk7k    openssl@1.0.2k%clang
+  i426yu3        ^zlib@1.2.8%clang
 
-  yfx6p3g    libdwarf@20160507%gcc
-  csrt4qx        ^libelf@0.8.13%gcc
+  i426yu3    zlib@1.2.8%clang
 
-  ipggckv    libelf@0.8.12%gcc
+  4pt75q7    zlib@1.2.11%clang
 
-  vrv2ttb    libelf@0.8.12%gcc cppflags="-O3"
 
-  csrt4qx    libelf@0.8.13%gcc
+  -- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
+  bq2wtdx    zlib@1.2.11%gcc
 
 
-  -- linux-redhat6-x86_64 / intel@15.0.4 --------------------------
-  w33hrej    libelf@0.8.13%intel
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  gyxmhgb    openssl@1.0.2k%gcc
+  64mns5m        ^zlib@1.2.8%gcc cppflags="-O3"
 
+  2woov64    openssl@1.0.2k%gcc
+  5nus6kn        ^zlib@1.2.11%gcc
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  csruprg    libdwarf@20160507%intel
-  4blbe3q        ^libelf@0.8.12%intel
+  bkyl5bh    zlib@1.2.8%gcc
 
-  4blbe3q    libelf@0.8.12%intel
+  64mns5m    zlib@1.2.8%gcc cppflags="-O3"
 
-  7wgp32x    libelf@0.8.13%intel
+  5nus6kn    zlib@1.2.11%gcc
 
 
-As we get to more complex packages, full installs will take too long to
-build in the time allotted for this tutorial. Our collaborators at CERN
-have been working on binary caching for Spack, which would allow for very
-fast installs of previously built packages. We are still working out the
-security ramifications of the feature, but it is coming soon.
-
-For now, we will switch to doing "fake" installs. When supplied with the
-``--fake`` flag (primarily used for debugging), Spack computes build
-metadata the same way it normally would, but it does not download the
-source or run the install script for a pacakge. We can use this to
-quickly demonstrate some of the more advanced Spack features in our
-limited tutorial time.
-
-``HDF5`` is an example of a more complicated package, with an MPI
-dependency. If we install it "out of the box," it will build with
-``openmpi``.
+Let's move on to slightly more complicated packages. ``HDF5`` is a
+good example of a more complicated package, with an MPI dependency. If
+we install it "out of the box," it will build with ``openmpi``.
 
 .. code-block:: console
 
-  $ spack install --fake hdf5
-  ==> Installing hdf5
-  ==> Installing zlib
-  ==> Building zlib [Package]
-  ==> Successfully installed zlib
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Installing openmpi
-  ==> Installing hwloc
-  ==> Installing libpciaccess
-  ==> Installing util-macros
-  ==> Building util-macros [Package]
-  ==> Successfully installed util-macros
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/util-macros-1.19.0-pc6zhs4cnkmg2cv4et4fizsp6scuvacg
-  ==> Installing libtool
-  ==> Installing m4
+  $ spack install --use-cache hdf5
   ==> Installing libsigsegv
-  ==> Building libsigsegv [Package]
-  ==> Successfully installed libsigsegv
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libsigsegv-2.10-q4cok3yber7lhf3jswg6mysg7oi53unh
-  ==> Building m4 [Package]
-  ==> Successfully installed m4
-    Fetch: .  Build: 0.23s.  Total: 0.23s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> Building libtool [Package]
-  ==> Successfully installed libtool
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libtool-2.4.6-rdx5nkfjwlvcanz5il3ys2pe34j4vxx5
+  ==> Searching for binary cache of libsigsegv
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-openssl-1.0.2k-gyxmhgbam26d7y42omb7xrvkjjgmzwio.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing libsigsegv from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/libsigsegv-2.11/linux-ubuntu16.04-x86_64-gcc-5.4.0-libsigsegv-2.11-fypapcprssrj3nstp6njprskeyynsgaz.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:21:10 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed libsigsegv from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libsigsegv-2.11-fypapcprssrj3nstp6njprskeyynsgaz
+  ==> Installing m4
+  ==> Searching for binary cache of m4
+  ==> Installing m4 from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/m4-1.4.18/linux-ubuntu16.04-x86_64-gcc-5.4.0-m4-1.4.18-r5envx3kqctwwflhd4qax4ahqtt6x43a.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:22:03 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed m4 from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/m4-1.4.18-r5envx3kqctwwflhd4qax4ahqtt6x43a
+  ==> Installing libtool
+  ==> Searching for binary cache of libtool
+  ==> Installing libtool from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/libtool-2.4.6/linux-ubuntu16.04-x86_64-gcc-5.4.0-libtool-2.4.6-o2pfwjf44353ajgr42xqtvzyvqsazkgu.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:29:09 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed libtool from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libtool-2.4.6-o2pfwjf44353ajgr42xqtvzyvqsazkgu
   ==> Installing pkg-config
-  ==> Building pkg-config [Package]
-  ==> Successfully installed pkg-config
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/pkg-config-0.29.1-wpjnlzahdw6ahkrgmqyeugkj2zhv4tui
-  ==> Building libpciaccess [Package]
-  ==> Successfully installed libpciaccess
-    Fetch: .  Build: 0.10s.  Total: 0.10s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libpciaccess-0.13.4-m2f6fpm22rpprq2ihkmfx6llf363264m
-  ==> Building hwloc [Package]
-  ==> Successfully installed hwloc
-    Fetch: .  Build: 0.23s.  Total: 0.23s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hwloc-1.11.4-xpb6hbl2hsze25cgdgfnoppn6rchhzaz
-  ==> Building openmpi [Package]
-  ==> Successfully installed openmpi
-    Fetch: .  Build: 0.35s.  Total: 0.35s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> Building hdf5 [AutotoolsPackage]
-  ==> Successfully installed hdf5
-    Fetch: .  Build: 0.61s.  Total: 0.61s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-ezvtnox35albuaxqryuondweyjgeo6es
-
+  ==> Searching for binary cache of pkg-config
+  ==> Installing pkg-config from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/pkg-config-0.29.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-pkg-config-0.29.2-ae2hwm7q57byfbxtymts55xppqwk7ecj.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:30:13 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed pkg-config from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/pkg-config-0.29.2-ae2hwm7q57byfbxtymts55xppqwk7ecj
+  ==> Installing util-macros
+  ==> Searching for binary cache of util-macros
+  ==> Installing util-macros from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/util-macros-1.19.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-util-macros-1.19.1-milz7fmttmptcic2qdk5cnel7ll5sybr.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:30:12 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed util-macros from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/util-macros-1.19.1-milz7fmttmptcic2qdk5cnel7ll5sybr
+  ==> Installing libpciaccess
+  ==> Searching for binary cache of libpciaccess
+  ==> Installing libpciaccess from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/libpciaccess-0.13.5/linux-ubuntu16.04-x86_64-gcc-5.4.0-libpciaccess-0.13.5-5urc6tcjae26fbbd2wyfohoszhgxtbmc.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:23 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed libpciaccess from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libpciaccess-0.13.5-5urc6tcjae26fbbd2wyfohoszhgxtbmc
+  ==> Installing xz
+  ==> Searching for binary cache of xz
+  ==> Installing xz from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/xz-5.2.3/linux-ubuntu16.04-x86_64-gcc-5.4.0-xz-5.2.3-htnq7wqdrqtof6uxqicdj3f7oe3xz6pw.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:34 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed xz from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/xz-5.2.3-htnq7wqdrqtof6uxqicdj3f7oe3xz6pw
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+  ==> Installing libxml2
+  ==> Searching for binary cache of libxml2
+  ==> Installing libxml2 from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/libxml2-2.9.4/linux-ubuntu16.04-x86_64-gcc-5.4.0-libxml2-2.9.4-sxk64lvcxhqjflzesnf3ye4wakovwi45.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:23 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed libxml2 from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libxml2-2.9.4-sxk64lvcxhqjflzesnf3ye4wakovwi45
+  ==> Installing hwloc
+  ==> Searching for binary cache of hwloc
+  ==> Installing hwloc from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hwloc-1.11.8/linux-ubuntu16.04-x86_64-gcc-5.4.0-hwloc-1.11.8-ivg4d2e6anxwin4zbld2g4qlrbuquoyg.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:32 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed hwloc from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hwloc-1.11.8-ivg4d2e6anxwin4zbld2g4qlrbuquoyg
+  ==> Installing openmpi
+  ==> Searching for binary cache of openmpi
+  ==> Installing openmpi from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/openmpi-3.0.0/linux-ubuntu16.04-x86_64-gcc-5.4.0-openmpi-3.0.0-yo5qkfvumpmgmvlbalqcadu46j5bd52f.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:43:34 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed openmpi from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openmpi-3.0.0-yo5qkfvumpmgmvlbalqcadu46j5bd52f
+  ==> Installing hdf5
+  ==> Searching for binary cache of hdf5
+  ==> Installing hdf5 from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-hdf5-1.10.1-bovz45ms24pmfr7hlckf56bxegfc4rea.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:53:08 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed hdf5 from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-bovz45ms24pmfr7hlckf56bxegfc4rea
 
 Spack packages can also have variants. Boolean variants can be specified
 using the ``+`` and ``~`` or ``-`` sigils. There are two sigils for
@@ -451,14 +589,28 @@ support.
 
 .. code-block:: console
 
-  $ spack install --fake hdf5~mpi
-  ==> Installing hdf5
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Building hdf5 [AutotoolsPackage]
-  ==> Successfully installed hdf5
-    Fetch: .  Build: 0.22s.  Total: 0.22s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-twppaioxqn6lti4grgopnmhwcq3h2rpw
-
+   $ spack install --use-cache hdf5~mpi
+   ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+   ==> Installing hdf5
+   ==> Searching for binary cache of hdf5
+   ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+   ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-openmpi-3.0.0-yo5qkfvumpmgmvlbalqcadu46j5bd52f.spec.yaml
+   ######################################################################## 100.0%
+   ...
+   ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-util-macros-1.19.1-milz7fmttmptcic2qdk5cnel7ll5sybr.spec.yaml
+   ######################################################################## 100.0%
+   ==> Installing hdf5 from binary cache
+   ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-hdf5-1.10.1-pa6oqzfeqzkqkzqr2375fqyt3qggx3tr.spack
+   ######################################################################## 100.0%
+   gpg: Signature made Sat 11 Nov 2017 12:53:40 AM UTC using RSA key ID 3B7C69B2
+   gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+   gpg: WARNING: This key is not certified with a trusted signature!
+   gpg:          There is no indication that the signature belongs to the owner.
+   Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+   ==> Relocating package from
+     /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+   ==> Successfully installed hdf5 from binary cache
+   [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-pa6oqzfeqzkqkzqr2375fqyt3qggx3tr
 
 We might also want to install HDF5 with a different MPI
 implementation. While MPI is not a package itself, packages can depend on
@@ -475,84 +627,120 @@ by any of several providers.
 
 .. code-block:: console
 
-  $ spack install --fake hdf5+mpi ^mpich
+  $ spack install --use-cache hdf5+hl+mpi ^mpich
+  ==> Installing mpich
+  ==> Searching for binary cache of mpich
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-hdf5-1.10.1-pa6oqzfeqzkqkzqr2375fqyt3qggx3tr.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing mpich from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpich-3.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-mpich-3.2-cymrnoowcc4vdyvdnf5ypvob4cmdadk5.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:45:26 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed mpich from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpich-3.2-cymrnoowcc4vdyvdnf5ypvob4cmdadk5
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
   ==> Installing hdf5
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Building hdf5 [AutotoolsPackage]
-  ==> Successfully installed hdf5
-    Fetch: .  Build: 0.38s.  Total: 0.38s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-j36yfw25i6gdd3q4vwlupgkpwic4ua6m
-
+  ==> Searching for binary cache of hdf5
+  ==> Installing hdf5 from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-hdf5-1.10.1-e4gz6f2l5ik3ijuk3alwsqplex4tbvin.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:49:45 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed hdf5 from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-e4gz6f2l5ik3ijuk3alwsqplex4tbvin
 
 We'll do a quick check in on what we have installed so far.
 
 .. code-block:: console
 
   $ spack find -ldf
-  ==> 22 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  twppaio    hdf5@1.10.0-patch1%gcc
-  ayc4jq7        ^zlib@1.2.8%gcc
+  ==> 23 installed packages.
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  ufruk7k    openssl@1.0.2k%clang
+  i426yu3        ^zlib@1.2.8%clang
+
+  i426yu3    zlib@1.2.8%clang
 
-  j36yfw2    hdf5@1.10.0-patch1%gcc
-  5jlp2nd        ^mpich@3.2%gcc
-  ayc4jq7        ^zlib@1.2.8%gcc
+  4pt75q7    zlib@1.2.11%clang
 
-  ezvtnox    hdf5@1.10.0-patch1%gcc
-  j4cgoq4        ^openmpi@2.0.1%gcc
-  xpb6hbl            ^hwloc@1.11.4%gcc
-  m2f6fpm                ^libpciaccess@0.13.4%gcc
-  ayc4jq7        ^zlib@1.2.8%gcc
 
-  xpb6hbl    hwloc@1.11.4%gcc
-  m2f6fpm        ^libpciaccess@0.13.4%gcc
+  -- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
+  bq2wtdx    zlib@1.2.11%gcc
 
-  dtg3tgn    libdwarf@20160507%gcc
-  vrv2ttb        ^libelf@0.8.12%gcc cppflags="-O3"
 
-  yfx6p3g    libdwarf@20160507%gcc
-  csrt4qx        ^libelf@0.8.13%gcc
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  pa6oqzf    hdf5@1.10.1%gcc
+  5nus6kn        ^zlib@1.2.11%gcc
 
-  ipggckv    libelf@0.8.12%gcc
+  bovz45m    hdf5@1.10.1%gcc
+  yo5qkfv        ^openmpi@3.0.0%gcc
+  ivg4d2e            ^hwloc@1.11.8%gcc
+  5urc6tc                ^libpciaccess@0.13.5%gcc
+  sxk64lv                ^libxml2@2.9.4%gcc
+  htnq7wq                    ^xz@5.2.3%gcc
+  5nus6kn                    ^zlib@1.2.11%gcc
 
-  vrv2ttb    libelf@0.8.12%gcc cppflags="-O3"
+  e4gz6f2    hdf5@1.10.1%gcc
+  cymrnoo        ^mpich@3.2%gcc
+  5nus6kn        ^zlib@1.2.11%gcc
 
-  csrt4qx    libelf@0.8.13%gcc
+  ivg4d2e    hwloc@1.11.8%gcc
+  5urc6tc        ^libpciaccess@0.13.5%gcc
+  sxk64lv        ^libxml2@2.9.4%gcc
+  htnq7wq            ^xz@5.2.3%gcc
+  5nus6kn            ^zlib@1.2.11%gcc
 
-  m2f6fpm    libpciaccess@0.13.4%gcc
+  5urc6tc    libpciaccess@0.13.5%gcc
 
-  q4cok3y    libsigsegv@2.10%gcc
+  fypapcp    libsigsegv@2.11%gcc
 
-  rdx5nkf    libtool@2.4.6%gcc
+  o2pfwjf    libtool@2.4.6%gcc
 
-  qijdzvh    m4@1.4.17%gcc
-  q4cok3y        ^libsigsegv@2.10%gcc
+  sxk64lv    libxml2@2.9.4%gcc
+  htnq7wq        ^xz@5.2.3%gcc
+  5nus6kn        ^zlib@1.2.11%gcc
 
-  5jlp2nd    mpich@3.2%gcc
+  r5envx3    m4@1.4.18%gcc
+  fypapcp        ^libsigsegv@2.11%gcc
 
-  j4cgoq4    openmpi@2.0.1%gcc
-  xpb6hbl        ^hwloc@1.11.4%gcc
-  m2f6fpm            ^libpciaccess@0.13.4%gcc
+  cymrnoo    mpich@3.2%gcc
 
-  wpjnlza    pkg-config@0.29.1%gcc
+  yo5qkfv    openmpi@3.0.0%gcc
+  ivg4d2e        ^hwloc@1.11.8%gcc
+  5urc6tc            ^libpciaccess@0.13.5%gcc
+  sxk64lv            ^libxml2@2.9.4%gcc
+  htnq7wq                ^xz@5.2.3%gcc
+  5nus6kn                ^zlib@1.2.11%gcc
 
-  pc6zhs4    util-macros@1.19.0%gcc
+  gyxmhgb    openssl@1.0.2k%gcc
+  64mns5m        ^zlib@1.2.8%gcc cppflags="-O3"
 
-  ayc4jq7    zlib@1.2.8%gcc
+  2woov64    openssl@1.0.2k%gcc
+  5nus6kn        ^zlib@1.2.11%gcc
 
+  ae2hwm7    pkg-config@0.29.2%gcc
 
-  -- linux-redhat6-x86_64 / intel@15.0.4 --------------------------
-  w33hrej    libelf@0.8.13%intel
+  milz7fm    util-macros@1.19.1%gcc
 
+  htnq7wq    xz@5.2.3%gcc
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  csruprg    libdwarf@20160507%intel
-  4blbe3q        ^libelf@0.8.12%intel
+  bkyl5bh    zlib@1.2.8%gcc
 
-  4blbe3q    libelf@0.8.12%intel
+  64mns5m    zlib@1.2.8%gcc cppflags="-O3"
 
-  7wgp32x    libelf@0.8.13%intel
+  5nus6kn    zlib@1.2.11%gcc
 
 
 Spack models the dependencies of packages as a directed acyclic graph
@@ -562,7 +750,7 @@ DAG as a graph.
 
 .. code-block:: console
 
-  $ spack graph hdf5+mpi ^mpich
+  $ spack graph hdf5+hl+mpi ^mpich
   o  hdf5
   |\
   o |  zlib
@@ -582,198 +770,277 @@ consistency requirements. It is entirely possible to have two packages
 using different versions of a dependency to build, which obviously cannot
 be done with linked dependencies.
 
-``HDF5`` is more complicated than our basic example of libelf and
-libdwarf, but it's still within the realm of software that an experienced
+``HDF5`` is more complicated than our basic example of zlib and
+openssl, but it's still within the realm of software that an experienced
 HPC user could reasonably expect to install given a bit of time. Now
-let's look at a more complicated package.
+let's look at an even more complicated package.
 
 .. code-block:: console
 
-  $ spack install --fake trilinos
-  ==> Installing trilinos
-  ==> Installing superlu-dist
-  ==> openmpi is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> Installing parmetis
-  ==> openmpi is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> Installing cmake
+  $ spack install --use-cache trilinos
   ==> Installing bzip2
-  ==> Building bzip2 [Package]
-  ==> Successfully installed bzip2
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/bzip2-1.0.6-gll2xsahysy7ji5gkmfxwkofdt3mwjhs
-  ==> expat is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/expat-2.2.0-mg5kwd3kluxdgorj32vzbp7aksg3vqej
+  ==> Searching for binary cache of bzip2
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-hdf5-1.10.1-e4gz6f2l5ik3ijuk3alwsqplex4tbvin.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-mpich-3.2-cymrnoowcc4vdyvdnf5ypvob4cmdadk5.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing bzip2 from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/bzip2-1.0.6/linux-ubuntu16.04-x86_64-gcc-5.4.0-bzip2-1.0.6-ufczdvsqt6edesm36xiucyry7myhj7e7.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:39:37 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed bzip2 from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/bzip2-1.0.6-ufczdvsqt6edesm36xiucyry7myhj7e7
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+  ==> Installing boost
+  ==> Searching for binary cache of boost
+  ==> Installing boost from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/boost-1.65.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-boost-1.65.1-xxqnbqql5nup7rujer2ury3hsdgcumzb.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:43:14 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed boost from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/boost-1.65.1-xxqnbqql5nup7rujer2ury3hsdgcumzb
+  ==> pkg-config is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/pkg-config-0.29.2-ae2hwm7q57byfbxtymts55xppqwk7ecj
   ==> Installing ncurses
-  ==> Building ncurses [Package]
-  ==> Successfully installed ncurses
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/ncurses-6.0-fttg4astvrtq2buey4wq66tnyu7bgj2c
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Installing openssl
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Building openssl [Package]
-  ==> Successfully installed openssl
-    Fetch: .  Build: 0.23s.  Total: 0.23s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openssl-1.0.2j-kt5xyk2dkho6tzadnqlbnbujmljprylg
-  ==> Installing libarchive
-  ==> Installing lzma
-  ==> Building lzma [Package]
-  ==> Successfully installed lzma
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/lzma-4.32.7-hah2cdo3zbulz6yg5do6dvnfn6en5v5c
-  ==> Installing nettle
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> Installing gmp
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> Building gmp [AutotoolsPackage]
-  ==> Successfully installed gmp
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gmp-6.1.1-uwn4gfdtq3sywy5uf4f7znrh66oybikf
-  ==> Building nettle [Package]
-  ==> Successfully installed nettle
-    Fetch: .  Build: 0.18s.  Total: 0.18s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/nettle-3.2-w4ieitifcmrldo4ra7as63apagzf56ja
-  ==> bzip2 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/bzip2-1.0.6-gll2xsahysy7ji5gkmfxwkofdt3mwjhs
-  ==> expat is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/expat-2.2.0-mg5kwd3kluxdgorj32vzbp7aksg3vqej
-  ==> Installing libxml2
-  ==> Installing xz
-  ==> Building xz [Package]
-  ==> Successfully installed xz
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/xz-5.2.2-bxh6cpyqqozazm5okvjqk23sww3gccnf
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Building libxml2 [Package]
-  ==> Successfully installed libxml2
-    Fetch: .  Build: 0.35s.  Total: 0.35s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libxml2-2.9.4-un323rppyu5qipkegyf7flmymvtmunrx
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Installing lz4
-  ==> Building lz4 [Package]
-  ==> Successfully installed lz4
-    Fetch: .  Build: 0.12s.  Total: 0.12s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/lz4-131-ivy2fcaw7ywujx74weebdi5bsm7q4vkc
-  ==> openssl is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openssl-1.0.2j-kt5xyk2dkho6tzadnqlbnbujmljprylg
-  ==> xz is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/xz-5.2.2-bxh6cpyqqozazm5okvjqk23sww3gccnf
-  ==> Installing lzo
-  ==> Building lzo [AutotoolsPackage]
-  ==> Successfully installed lzo
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/lzo-2.09-dlgnm74ozo6baactkft5oah2jre2ri2i
-  ==> Building libarchive [Package]
-  ==> Successfully installed libarchive
-    Fetch: .  Build: 1.35s.  Total: 1.35s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libarchive-3.2.1-biq3kebw7vel7njusill7vv7mjldkqjv
-  ==> xz is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/xz-5.2.2-bxh6cpyqqozazm5okvjqk23sww3gccnf
-  ==> Installing curl
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> openssl is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openssl-1.0.2j-kt5xyk2dkho6tzadnqlbnbujmljprylg
-  ==> Building curl [Package]
-  ==> Successfully installed curl
-    Fetch: .  Build: 0.36s.  Total: 0.36s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/curl-7.50.3-oze4gqutj4x2isbkcn5ob2bhhxbskod4
-  ==> Building cmake [Package]
-  ==> Successfully installed cmake
-    Fetch: .  Build: 1.64s.  Total: 1.64s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> Installing metis
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> Building metis [Package]
-  ==> Successfully installed metis
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
-  ==> Building parmetis [Package]
-  ==> Successfully installed parmetis
-    Fetch: .  Build: 0.62s.  Total: 0.62s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/parmetis-4.0.3-rtg6hml5t6acdcnxomn3l5zfiful4d2t
-  ==> Installing openblas
-  ==> Building openblas [Package]
-  ==> Successfully installed openblas
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> metis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
-  ==> Building superlu-dist [Package]
-  ==> Successfully installed superlu-dist
-    Fetch: .  Build: 0.85s.  Total: 0.85s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/superlu-dist-5.1.1-25r6jlvkpjnkiuwt2rtbzhk3l3htuxs7
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
+  ==> Searching for binary cache of ncurses
+  ==> Installing ncurses from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/ncurses-6.0/linux-ubuntu16.04-x86_64-gcc-5.4.0-ncurses-6.0-ukq4tccptm2rxd56d2bumqthnpcjzlez.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:06:38 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed ncurses from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/ncurses-6.0-ukq4tccptm2rxd56d2bumqthnpcjzlez
+  ==> openssl is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k-2woov64m3n4gjtnfp722qcyemzf2qtom
+  ==> Installing cmake
+  ==> Searching for binary cache of cmake
+  ==> Installing cmake from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/cmake-3.9.4/linux-ubuntu16.04-x86_64-gcc-5.4.0-cmake-3.9.4-a2lyofsoxutyy4ihvzopizpbjubtdoem.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 01:22:03 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed cmake from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/cmake-3.9.4-a2lyofsoxutyy4ihvzopizpbjubtdoem
   ==> Installing glm
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> Building glm [Package]
-  ==> Successfully installed glm
-    Fetch: .  Build: 0.12s.  Total: 0.12s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/glm-0.9.7.1-7a6oho4aerz7vftxd5ur7lywscht2iry
+  ==> Searching for binary cache of glm
+  ==> Installing glm from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/glm-0.9.7.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-glm-0.9.7.1-jnw622jwcbsymzj2fsx22omjl7tmvaws.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:38 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed glm from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/glm-0.9.7.1-jnw622jwcbsymzj2fsx22omjl7tmvaws
+  ==> libsigsegv is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libsigsegv-2.11-fypapcprssrj3nstp6njprskeyynsgaz
+  ==> m4 is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/m4-1.4.18-r5envx3kqctwwflhd4qax4ahqtt6x43a
+  ==> libtool is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libtool-2.4.6-o2pfwjf44353ajgr42xqtvzyvqsazkgu
+  ==> util-macros is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/util-macros-1.19.1-milz7fmttmptcic2qdk5cnel7ll5sybr
+  ==> libpciaccess is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libpciaccess-0.13.5-5urc6tcjae26fbbd2wyfohoszhgxtbmc
+  ==> xz is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/xz-5.2.3-htnq7wqdrqtof6uxqicdj3f7oe3xz6pw
+  ==> libxml2 is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libxml2-2.9.4-sxk64lvcxhqjflzesnf3ye4wakovwi45
+  ==> hwloc is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hwloc-1.11.8-ivg4d2e6anxwin4zbld2g4qlrbuquoyg
+  ==> openmpi is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openmpi-3.0.0-yo5qkfvumpmgmvlbalqcadu46j5bd52f
+  ==> Installing hdf5
+  ==> Searching for binary cache of hdf5
+  ==> Installing hdf5 from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-hdf5-1.10.1-d73xxpvfxgd2z2ypmuuwtxhoxmzdglez.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:39:36 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+  /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed hdf5 from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-d73xxpvfxgd2z2ypmuuwtxhoxmzdglez
+  ==> Installing openblas
+  ==> Searching for binary cache of openblas
+  ==> Installing openblas from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/openblas-0.2.20/linux-ubuntu16.04-x86_64-gcc-5.4.0-openblas-0.2.20-4dahl6ltbpojei4s3stbqbq5iuuqlaxo.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:43:22 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed openblas from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openblas-0.2.20-4dahl6ltbpojei4s3stbqbq5iuuqlaxo
   ==> Installing hypre
-  ==> openmpi is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building hypre [Package]
-  ==> Successfully installed hypre
-    Fetch: .  Build: 0.61s.  Total: 0.61s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hypre-2.11.1-lf7hcejiiww5peesh57quda72z67veit
-  ==> metis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
+  ==> Searching for binary cache of hypre
+  ==> Installing hypre from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hypre-2.12.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-hypre-2.12.1-z3rgfzqc4gu4u4qvveyo2dqqzl2j463z.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:17 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed hypre from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hypre-2.12.1-z3rgfzqc4gu4u4qvveyo2dqqzl2j463z
+  ==> Installing matio
+  ==> Searching for binary cache of matio
+  ==> Installing matio from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/matio-1.5.9/linux-ubuntu16.04-x86_64-gcc-5.4.0-matio-1.5.9-4ajrcuhdf5uktotnrfzufufy5vbd6any.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:24 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed matio from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/matio-1.5.9-4ajrcuhdf5uktotnrfzufufy5vbd6any
+  ==> Installing metis
+  ==> Searching for binary cache of metis
+  ==> Installing metis from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/metis-5.1.0/linux-ubuntu16.04-x86_64-gcc-5.4.0-metis-5.1.0-m34qytcqsvsaduxyh3wevf3kj6pbzyw6.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:39:28 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+  /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed metis from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/metis-5.1.0-m34qytcqsvsaduxyh3wevf3kj6pbzyw6
   ==> Installing netlib-scalapack
-  ==> openmpi is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building netlib-scalapack [Package]
-  ==> Successfully installed netlib-scalapack
-    Fetch: .  Build: 0.61s.  Total: 0.61s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/netlib-scalapack-2.0.2-dvcanz2qq4dfcexznbhbmzbxfj43uz4q
-  ==> Installing suite-sparse
-  ==> Installing tbb
-  ==> Building tbb [Package]
-  ==> Successfully installed tbb
-    Fetch: .  Build: 0.12s.  Total: 0.12s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/tbb-4.4.4-zawzkkhrmdonbjpj3a5bb6gkgnqlrjeu
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> metis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
-  ==> Building suite-sparse [Package]
-  ==> Successfully installed suite-sparse
-    Fetch: .  Build: 0.49s.  Total: 0.49s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/suite-sparse-4.5.3-lvur6hriy2j7xfjwh5punp3exwpynzm6
-  ==> openmpi is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> Installing netcdf
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> curl is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/curl-7.50.3-oze4gqutj4x2isbkcn5ob2bhhxbskod4
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> hdf5 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-ezvtnox35albuaxqryuondweyjgeo6es
-  ==> Building netcdf [Package]
-  ==> Successfully installed netcdf
-    Fetch: .  Build: 0.90s.  Total: 0.90s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/netcdf-4.4.1-tcl4zbrmdfrit2cqlaxig6xieu5h552j
+  ==> Searching for binary cache of netlib-scalapack
+  ==> Installing netlib-scalapack from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/netlib-scalapack-2.0.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-netlib-scalapack-2.0.2-xudg7xypr63nte6ifrdsmllilxbrfiar.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:28 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed netlib-scalapack from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/netlib-scalapack-2.0.2-xudg7xypr63nte6ifrdsmllilxbrfiar
   ==> Installing mumps
-  ==> netlib-scalapack is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/netlib-scalapack-2.0.2-dvcanz2qq4dfcexznbhbmzbxfj43uz4q
-  ==> openmpi is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openmpi-2.0.1-j4cgoq4furxvr73pq72r2qgywgksw3qn
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building mumps [Package]
-  ==> Successfully installed mumps
-    Fetch: .  Build: 0.74s.  Total: 0.74s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mumps-5.0.2-kr5r4nnx5tfcacxnk3ii5dsxbe6pu5fy
-  ==> Installing matio
-  ==> Building matio [Package]
-  ==> Successfully installed matio
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/matio-1.5.2-4zrozucookychlvc4q53omp2zyfk2bed
-  ==> Installing boost
-  ==> bzip2 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/bzip2-1.0.6-gll2xsahysy7ji5gkmfxwkofdt3mwjhs
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> Building boost [Package]
-  ==> Successfully installed boost
-    Fetch: .  Build: 0.35s.  Total: 0.35s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/boost-1.62.0-je7eqvzt74kezwhh55y5lwt5dy6pnali
-  ==> parmetis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/parmetis-4.0.3-rtg6hml5t6acdcnxomn3l5zfiful4d2t
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> hdf5 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-ezvtnox35albuaxqryuondweyjgeo6es
-  ==> Building trilinos [Package]
-  ==> Successfully installed trilinos
-    Fetch: .  Build: 2.63s.  Total: 2.63s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/trilinos-12.8.1-uvd6dfd7x4uyvck4awo3r3frudihn4ar
-
-
-Now we're starting to see the power of Spack. Trilinos has 11 top level
-dependecies, many of which have dependencies of their own. Installing
-more complex packages can take days or weeks even for an experienced
-user. Although we've done a fake installation for the tutorial, a real
-installation of trilinos using Spack takes about 3 hours (depending on
-the system), but only 20 seconds of programmer time.
+  ==> Searching for binary cache of mumps
+  ==> Installing mumps from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/mumps-5.1.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-mumps-5.1.1-5a7hgodxoze47xqd32jcxhvzctex4ezx.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:15 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed mumps from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/mumps-5.1.1-5a7hgodxoze47xqd32jcxhvzctex4ezx
+  ==> Installing netcdf
+  ==> Searching for binary cache of netcdf
+  ==> Installing netcdf from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/netcdf-4.4.1.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-netcdf-4.4.1.1-gk2xxhbqijnrdwicawawcll4t3c7dvoj.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:43:37 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed netcdf from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/netcdf-4.4.1.1-gk2xxhbqijnrdwicawawcll4t3c7dvoj
+  ==> Installing parmetis
+  ==> Searching for binary cache of parmetis
+  ==> Installing parmetis from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/parmetis-4.0.3/linux-ubuntu16.04-x86_64-gcc-5.4.0-parmetis-4.0.3-o4qdo7aylhejov2e5ii7tagrnw6qrrlo.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:39:37 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+  /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed parmetis from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/parmetis-4.0.3-o4qdo7aylhejov2e5ii7tagrnw6qrrlo
+  ==> Installing suite-sparse
+  ==> Searching for binary cache of suite-sparse
+  ==> Installing suite-sparse from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/suite-sparse-4.5.5/linux-ubuntu16.04-x86_64-gcc-5.4.0-suite-sparse-4.5.5-bg67crx4ltmxulnumuxjxqzrcobpmyzg.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:30:31 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed suite-sparse from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/suite-sparse-4.5.5-bg67crx4ltmxulnumuxjxqzrcobpmyzg
+  ==> Installing superlu-dist
+  ==> Searching for binary cache of superlu-dist
+  ==> Installing superlu-dist from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/superlu-dist-5.2.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-superlu-dist-5.2.2-gggsamgizi2dwmwxglgzbxvg6hkamhol.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:43:35 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed superlu-dist from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/superlu-dist-5.2.2-gggsamgizi2dwmwxglgzbxvg6hkamhol
+  ==> Installing trilinos
+  ==> Searching for binary cache of trilinos
+  ==> Installing trilinos from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-trilinos-12.12.1-istwe3b43b7etgtrhcuzjem3p5gonc6h.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 11:47:19 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed trilinos from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-istwe3b43b7etgtrhcuzjem3p5gonc6h
+
+Now we're starting to see the power of Spack. Trilinos has 11 top
+level dependecies, many of which have dependencies of their
+own. Installing more complex packages can take days or weeks even for
+an experienced user. Although we've done a binary installation for the
+tutorial, a source installation of trilinos using Spack takes about 3
+hours (depending on the system), but only 20 seconds of programmer
+time.
 
 Spack manages constistency of the entire DAG. Every MPI dependency will
 be satisfied by the same configuration of MPI, etc. If we install
@@ -782,70 +1049,143 @@ with ``mpich``:
 
 .. code-block:: console
 
-  $ spack install --fake trilinos ^hdf5+mpi ^mpich
-  ==> Installing trilinos
-  ==> Installing superlu-dist
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> metis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
-  ==> Installing parmetis
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> metis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> Building parmetis [Package]
-  ==> Successfully installed parmetis
-    Fetch: .  Build: 0.38s.  Total: 0.38s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/parmetis-4.0.3-43kbtni6p5y446c6qdkybq4htj7ot4zn
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building superlu-dist [Package]
-  ==> Successfully installed superlu-dist
-    Fetch: .  Build: 0.61s.  Total: 0.61s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/superlu-dist-5.1.1-46uuupehmonx5jicc6xnegnud2n5jqyl
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> glm is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/glm-0.9.7.1-7a6oho4aerz7vftxd5ur7lywscht2iry
+  $ spack install --use-cache trilinos +hdf5 ^hdf5+hl+mpi ^mpich
+  ==> bzip2 is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/bzip2-1.0.6-ufczdvsqt6edesm36xiucyry7myhj7e7
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+  ==> boost is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/boost-1.65.1-xxqnbqql5nup7rujer2ury3hsdgcumzb
+  ==> pkg-config is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/pkg-config-0.29.2-ae2hwm7q57byfbxtymts55xppqwk7ecj
+  ==> ncurses is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/ncurses-6.0-ukq4tccptm2rxd56d2bumqthnpcjzlez
+  ==> openssl is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k-2woov64m3n4gjtnfp722qcyemzf2qtom
+  ==> cmake is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/cmake-3.9.4-a2lyofsoxutyy4ihvzopizpbjubtdoem
+  ==> glm is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/glm-0.9.7.1-jnw622jwcbsymzj2fsx22omjl7tmvaws
+  ==> mpich is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpich-3.2-cymrnoowcc4vdyvdnf5ypvob4cmdadk5
+  ==> hdf5 is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-e4gz6f2l5ik3ijuk3alwsqplex4tbvin
+  ==> openblas is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openblas-0.2.20-4dahl6ltbpojei4s3stbqbq5iuuqlaxo
   ==> Installing hypre
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building hypre [Package]
-  ==> Successfully installed hypre
-    Fetch: .  Build: 0.37s.  Total: 0.37s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hypre-2.11.1-6ajnyymoivs5apajd7thjisae36jv4lz
-  ==> metis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/metis-5.1.0-ithifyl4xvqbn76js23wsb4tjnztrbdv
+  ==> Searching for binary cache of hypre
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-netcdf-4.4.1.1-gk2xxhbqijnrdwicawawcll4t3c7dvoj.spec.yaml
+  ######################################################################## 100.0%
+  ...
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-bzip2-1.0.6-ufczdvsqt6edesm36xiucyry7myhj7e7.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-boost-1.65.1-xxqnbqql5nup7rujer2ury3hsdgcumzb.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing hypre from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/hypre-2.12.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-hypre-2.12.1-3psjg2ka2qa26jtgitlil4vglqr67anj.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:49:37 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed hypre from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hypre-2.12.1-3psjg2ka2qa26jtgitlil4vglqr67anj
+  ==> Installing matio
+  ==> Searching for binary cache of matio
+  ==> Installing matio from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/matio-1.5.9/linux-ubuntu16.04-x86_64-gcc-5.4.0-matio-1.5.9-3ibrutc6cs7x6ybyt5ni5n6djtq5okm2.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:45:26 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed matio from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/matio-1.5.9-3ibrutc6cs7x6ybyt5ni5n6djtq5okm2
+  ==> metis is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/metis-5.1.0-m34qytcqsvsaduxyh3wevf3kj6pbzyw6
   ==> Installing netlib-scalapack
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> cmake is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/cmake-3.6.1-n2nkknrku6dvuneo3rjumim7axt7n36e
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building netlib-scalapack [Package]
-  ==> Successfully installed netlib-scalapack
-    Fetch: .  Build: 0.37s.  Total: 0.37s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/netlib-scalapack-2.0.2-dayeep27omm26wksd3iqvbu3gezc2eoh
-  ==> suite-sparse is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/suite-sparse-4.5.3-lvur6hriy2j7xfjwh5punp3exwpynzm6
-  ==> Installing netcdf
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> curl is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/curl-7.50.3-oze4gqutj4x2isbkcn5ob2bhhxbskod4
-  ==> zlib is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/zlib-1.2.8-ayc4jq7vxuzge5n444gutvskeytfdruh
-  ==> hdf5 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-j36yfw25i6gdd3q4vwlupgkpwic4ua6m
-  ==> Building netcdf [Package]
-  ==> Successfully installed netcdf
-    Fetch: .  Build: 0.67s.  Total: 0.67s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/netcdf-4.4.1-gfemi4jk4qltvp33xhtpkam7dozbqvhq
+  ==> Searching for binary cache of netlib-scalapack
+  ==> Installing netlib-scalapack from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/netlib-scalapack-2.0.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-netlib-scalapack-2.0.2-km7tsbgoyyywonyejkjoojskhc5knz3z.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:49:49 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed netlib-scalapack from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/netlib-scalapack-2.0.2-km7tsbgoyyywonyejkjoojskhc5knz3z
   ==> Installing mumps
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> netlib-scalapack is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/netlib-scalapack-2.0.2-dayeep27omm26wksd3iqvbu3gezc2eoh
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> Building mumps [Package]
-  ==> Successfully installed mumps
-    Fetch: .  Build: 0.49s.  Total: 0.49s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mumps-5.0.2-w7t5pl3jhhwitfiyer63zj6zv7idkt3m
-  ==> mpich is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpich-3.2-5jlp2ndnsb67txggraglu47vjmayx5za
-  ==> matio is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/matio-1.5.2-4zrozucookychlvc4q53omp2zyfk2bed
-  ==> boost is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/boost-1.62.0-je7eqvzt74kezwhh55y5lwt5dy6pnali
-  ==> parmetis is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/parmetis-4.0.3-43kbtni6p5y446c6qdkybq4htj7ot4zn
-  ==> openblas is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/openblas-0.2.19-bwofa7fhff6od5zn56vy3j4eeyupsqgt
-  ==> hdf5 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-j36yfw25i6gdd3q4vwlupgkpwic4ua6m
-  ==> Building trilinos [Package]
-  ==> Successfully installed trilinos
-    Fetch: .  Build: 2.42s.  Total: 2.42s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/trilinos-12.8.1-ffwrpxnq7lhiw2abxn2u7ffr4jjsdwep
+  ==> Searching for binary cache of mumps
+  ==> Installing mumps from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/mumps-5.1.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-mumps-5.1.1-phvk6yhkzqed6gjsbah6dnhlesdclild.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:45:28 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed mumps from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/mumps-5.1.1-phvk6yhkzqed6gjsbah6dnhlesdclild
+  ==> libsigsegv is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libsigsegv-2.11-fypapcprssrj3nstp6njprskeyynsgaz
+  ==> m4 is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/m4-1.4.18-r5envx3kqctwwflhd4qax4ahqtt6x43a
+  ==> Installing netcdf
+  ==> Searching for binary cache of netcdf
+  ==> Installing netcdf from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/netcdf-4.4.1.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-netcdf-4.4.1.1-rmx4uppnhpv6kq7bh7r46zfqevgdkkgw.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:49:38 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed netcdf from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/netcdf-4.4.1.1-rmx4uppnhpv6kq7bh7r46zfqevgdkkgw
+  ==> Installing parmetis
+  ==> Searching for binary cache of parmetis
+  ==> Installing parmetis from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/parmetis-4.0.3/linux-ubuntu16.04-x86_64-gcc-5.4.0-parmetis-4.0.3-qk77g6aiqr3f2hsykg54zzuhlxcpdcmv.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:45:14 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed parmetis from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/parmetis-4.0.3-qk77g6aiqr3f2hsykg54zzuhlxcpdcmv
+  ==> suite-sparse is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/suite-sparse-4.5.5-bg67crx4ltmxulnumuxjxqzrcobpmyzg
+  ==> Installing superlu-dist
+  ==> Searching for binary cache of superlu-dist
+  ==> Installing superlu-dist from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/superlu-dist-5.2.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-superlu-dist-5.2.2-65vot2le3ezooz7tj6eveovly725o44x.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sat 11 Nov 2017 12:45:14 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed superlu-dist from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/superlu-dist-5.2.2-65vot2le3ezooz7tj6eveovly725o44x
+  ==> Installing trilinos
+  ==> Searching for binary cache of trilinos
+  ==> Installing trilinos from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-trilinos-12.12.1-xupifcp5d4f53cobm6g3xzao577uzezs.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 12:04:58 AM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed trilinos from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-xupifcp5d4f53cobm6g3xzao577uzezs
+
 
 We see that every package in the trilinos DAG that depends on MPI now
 uses ``mpich``.
@@ -854,51 +1194,46 @@ uses ``mpich``.
 
   $ spack find -d trilinos
   ==> 2 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-      trilinos@12.8.1
-          ^boost@1.62.0
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+      trilinos@12.12.1
+          ^boost@1.65.1
               ^bzip2@1.0.6
-              ^zlib@1.2.8
+              ^zlib@1.2.11
           ^glm@0.9.7.1
-          ^hdf5@1.10.0-patch1
-              ^mpich@3.2
-          ^hypre@2.11.1
-              ^openblas@0.2.19
-          ^matio@1.5.2
+          ^hdf5@1.10.1
+              ^openmpi@3.0.0
+                  ^hwloc@1.11.8
+                      ^libpciaccess@0.13.5
+                      ^libxml2@2.9.4
+                          ^xz@5.2.3
+          ^hypre@2.12.1
+              ^openblas@0.2.20
+          ^matio@1.5.9
           ^metis@5.1.0
-          ^mumps@5.0.2
+          ^mumps@5.1.1
               ^netlib-scalapack@2.0.2
-          ^netcdf@4.4.1
-              ^curl@7.50.3
-                  ^openssl@1.0.2j
+          ^netcdf@4.4.1.1
           ^parmetis@4.0.3
-          ^suite-sparse@4.5.3
-              ^tbb@4.4.4
-          ^superlu-dist@5.1.1
+          ^suite-sparse@4.5.5
+          ^superlu-dist@5.2.2
 
-      trilinos@12.8.1
-          ^boost@1.62.0
+      trilinos@12.12.1
+          ^boost@1.65.1
               ^bzip2@1.0.6
-              ^zlib@1.2.8
+              ^zlib@1.2.11
           ^glm@0.9.7.1
-          ^hdf5@1.10.0-patch1
-              ^openmpi@2.0.1
-                  ^hwloc@1.11.4
-                      ^libpciaccess@0.13.4
-          ^hypre@2.11.1
-              ^openblas@0.2.19
-          ^matio@1.5.2
+          ^hdf5@1.10.1
+              ^mpich@3.2
+          ^hypre@2.12.1
+              ^openblas@0.2.20
+          ^matio@1.5.9
           ^metis@5.1.0
-          ^mumps@5.0.2
+          ^mumps@5.1.1
               ^netlib-scalapack@2.0.2
-          ^netcdf@4.4.1
-              ^curl@7.50.3
-                  ^openssl@1.0.2j
+          ^netcdf@4.4.1.1
           ^parmetis@4.0.3
-          ^suite-sparse@4.5.3
-              ^tbb@4.4.4
-          ^superlu-dist@5.1.1
-
+          ^suite-sparse@4.5.5
+          ^superlu-dist@5.2.2
 
 As we discussed before, the ``spack find -d`` command shows the
 dependency information as a tree. While that is often sufficient, many
@@ -917,35 +1252,101 @@ command shows the full DAG of the dependency information.
   | | | | |\
   | | | | | |\
   | | | | | | |\
-  | o | | | | | |  netcdf
-  | |\ \ \ \ \ \ \
-  | | |\ \ \ \ \ \ \
-  | | | o | | | | | |  curl
-  | | |/| | | | | | |
-  | |/| | | | | | | |
-  | | | o | | | | | |  openssl
-  | | |/ / / / / / /
-  | |/| | | | | | |
-  | | o | | | | | |  hdf5
-  | |/| | | | | | |
-  | | |/ / / / / /
-  | o | | | | | |  zlib
-  |  / / / / / /
-  o | | | | | |  swig
-  o | | | | | |  pcre
-   / / / / / /
-  o | | | | |  mpi
-   / / / / /
-  o | | | |  matio
-   / / / /
-  o | | |  lapack
-   / / /
-  o | |  glm
-   / /
-  o |  boost
-   /
-  o  blas
-
+  | | | | | | | |\
+  | | | | | | | | |\
+  | | | | | | | | | |\
+  | | | | | | | | | | |\
+  | | | | | | | | | | | |\
+  | | | | | | | | | | | | |\
+  | | | | | | | | | | | | | |\
+  o | | | | | | | | | | | | | |  superlu-dist
+  |\ \ \ \ \ \ \ \ \ \ \ \ \ \ \
+  | |_|/ / / / / / / / / / / / /
+  |/| | | | | | | | | | | | | |
+  | |\ \ \ \ \ \ \ \ \ \ \ \ \ \
+  | | |_|/ / / / / / / / / / / /
+  | |/| | | | | | | | | | | | |
+  | | |\ \ \ \ \ \ \ \ \ \ \ \ \
+  | | | |_|/ / / / / / / / / / /
+  | | |/| | | | | | | | | | | |
+  | | | | |_|_|/ / / / / / / /
+  | | | |/| | | | | | | | | |
+  | | | | o | | | | | | | | |  suite-sparse
+  | | | |/| | | | | | | | | |
+  | | |/|/ / / / / / / / / /
+  o | | | | | | | | | | | |  parmetis
+  |\| | | | | | | | | | | |
+  |\ \ \ \ \ \ \ \ \ \ \ \ \
+  | |_|_|/ / / / / / / / / /
+  |/| | | | | | | | | | | |
+  | | |_|_|_|_|_|_|_|/ / /
+  | |/| | | | | | | | | |
+  | | | | | | o | | | | |  mumps
+  | | | |_|_|/| | | | | |
+  | | |/| |_|/| | | | | |
+  | | | |/| |/ / / / / /
+  | | | | |/| | | | | |
+  | | | | o | | | | | |  netlib-scalapack
+  | | |_|/| | | | | | |
+  | |/| |/| | | | | | |
+  | | |/|/ / / / / / /
+  o | | | | | | | | |  metis
+  |/ / / / / / / / /
+  | | | | | | | o |  glm
+  | |_|_|_|_|_|/ /
+  |/| | | | | | |
+  o | | | | | | |  cmake
+  |\ \ \ \ \ \ \ \
+  o | | | | | | | |  openssl
+  | | | | o | | | |  netcdf
+  | |_|_|/| | | | |
+  |/| | |/| | | | |
+  | | |/| | | | | |
+  | | | | |\ \ \ \ \
+  | | | | | | |_|/ /
+  | | | | | |/| | |
+  | | | | | | o | |  matio
+  | |_|_|_|_|/| | |
+  |/| | | | |/ / /
+  | | | | | | o |  hypre
+  | | | |_|_|/| |
+  | | |/| |_|/ /
+  | | | |/| | |
+  | | | | | o |  hdf5
+  | |_|_|_|/| |
+  |/| | |_|/ /
+  | | |/| | |
+  | | o | | |  openmpi
+  | | o | | |  hwloc
+  | | |\ \ \ \
+  | | | |\ \ \ \
+  | | | o | | | |  libxml2
+  | |_|/| | | | |
+  |/| |/| | | | |
+  | | | | | | | o  boost
+  | |_|_|_|_|_|/|
+  |/| | | | | | |
+  o | | | | | | |  zlib
+   / / / / / / /
+   | | o | | | |  xz
+   | |  / / / /
+   | | o | | |  libpciaccess
+   | |/| | | |
+   | | |\ \ \ \
+   | | o | | | |  util-macros
+   | |  / / / /
+   o | | | | |  ncurses
+   |/ / / / /
+   o | | | |  pkg-config
+    / / / /
+    | o | |  openblas
+    |  / /
+    o | |  libtool
+    |/ /
+    o |  m4
+    o |  libsigsegv
+     /
+     o  bzip2
 
 You can control how the output is displayed with a number of options.
 
@@ -963,100 +1364,92 @@ complicated packages. The output can be changed to the ``graphviz``
 Uninstalling Packages
 ---------------------
 
-Earlier we installed many configurations each of libelf and
-libdwarf. Now we will go through and uninstall some of those packages
+Earlier we installed many configurations each of zlib and
+openssl. Now we will go through and uninstall some of those packages
 that we didn't really need.
 
 .. code-block:: console
 
-  $ spack find -d libdwarf
+  $ spack find -d openssl
   ==> 3 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-      libdwarf@20160507
-          ^libelf@0.8.12
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+      openssl@1.0.2k
+          ^zlib@1.2.8
 
-      libdwarf@20160507
-          ^libelf@0.8.13
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+      openssl@1.0.2k
+          ^zlib@1.2.8
 
+      openssl@1.0.2k
+          ^zlib@1.2.11
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-      libdwarf@20160507
-          ^libelf@0.8.12
-
-  $ spack find libelf
+  $ spack find zlib
   ==> 6 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  libelf@0.8.12  libelf@0.8.12  libelf@0.8.13
-
-  -- linux-redhat6-x86_64 / intel@15.0.4 --------------------------
-  libelf@0.8.13
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  zlib@1.2.8  zlib@1.2.11
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  libelf@0.8.12  libelf@0.8.13
+  -- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
+  zlib@1.2.11
 
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  zlib@1.2.8  zlib@1.2.8  zlib@1.2.11
 
 We can uninstall packages by spec using the same syntax as install.
 
 .. code-block:: console
 
-  $ spack uninstall libelf%intel@15.0.4
-  ==> The following packages will be uninstalled :
-
-  -- linux-redhat6-x86_64 / intel@15.0.4 --------------------------
-  w33hrej libelf@0.8.13%intel
-
-
-  ==> Do you want to proceed? [y/n] y
-  ==> Successfully uninstalled libelf@0.8.13%intel@15.0.4 arch=linux-redhat6-x86_64-w33hrej
+  $ spack uninstall zlib %gcc@4.7
+  ==> The following packages will be uninstalled:
 
+  -- linux-ubuntu16.04-x86_64 / gcc@4.7 ---------------------------
+  bq2wtdx zlib@1.2.11%gcc+optimize+pic+shared
 
+  ==> Do you want to proceed? [y/N] y
+  ==> Successfully uninstalled zlib@1.2.11%gcc@4.7+optimize+pic+shared arch=linux-ubuntu16.04-x86_64 /bq2wtdx
 
-  $ spack find -lf libelf
+  $ spack find -lf zlib
   ==> 5 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  ipggckv libelf@0.8.12%gcc
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  i426yu3 zlib@1.2.8%clang
 
-  vrv2ttb libelf@0.8.12%gcc cppflags="-O3"
+  4pt75q7 zlib@1.2.11%clang
 
-  csrt4qx libelf@0.8.13%gcc
 
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  bkyl5bh zlib@1.2.8%gcc
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  4blbe3q libelf@0.8.12%intel
+  64mns5m zlib@1.2.8%gcc cppflags="-O3"
 
-  7wgp32x libelf@0.8.13%intel
-
-
-We can uninstall packages by referring only to their hash.
+  5nus6kn zlib@1.2.11%gcc
 
+We can also uninstall packages by referring only to their hash.
 
 We can use either ``-f`` (force) or ``-R`` (remove dependents as well) to
 remove packages that are required by another installed package.
 
 .. code-block:: console
 
-  $ spack uninstall /4blb
-  ==> Error: Will not uninstall libelf@0.8.12%intel@16.0.3-4blbe3q
+  $ spack uninstall zlib/i426
+  ==> Error: Will not uninstall zlib@1.2.8%clang@3.8.0-2ubuntu4/i426yu3
 
   The following packages depend on it:
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  csruprg libdwarf@20160507%intel
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  ufruk7k openssl@1.0.2k%clang
 
 
-  ==> Error: You can use spack uninstall --dependents to uninstall these dependencies as well
-  $ spack uninstall -R /4blb
-  ==> The following packages will be uninstalled :
+  ==> Error: Use \`spack uninstall --dependents\` to uninstall these dependencies as well.
 
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  csruprg libdwarf@20160507%intel
+  $ spack uninstall -R zlib/i426
+  ==> The following packages will be uninstalled:
 
-  4blbe3q libelf@0.8.12%intel
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+  ufruk7k openssl@1.0.2k%clang
 
+  i426yu3 zlib@1.2.8%clang+optimize+pic+shared
 
-  ==> Do you want to proceed? [y/n] y
-  ==> Successfully uninstalled libdwarf@20160507%intel@16.0.3 arch=linux-redhat6-x86_64-csruprg
-  ==> Successfully uninstalled libelf@0.8.12%intel@16.0.3 arch=linux-redhat6-x86_64-4blbe3q
-
+  ==> Do you want to proceed? [y/N] y
+  ==> Successfully uninstalled openssl@1.0.2k%clang@3.8.0-2ubuntu4 arch=linux-ubuntu16.04-x86_64 /ufruk7k
+  ==> Successfully uninstalled zlib@1.2.8%clang@3.8.0-2ubuntu4+optimize+pic+shared arch=linux-ubuntu16.04-x86_64 /i426yu3
 
 Spack will not uninstall packages that are not sufficiently
 specified. The ``-a`` (all) flag can be used to uninstall multiple
@@ -1067,27 +1460,25 @@ packages at once.
   $ spack uninstall trilinos
   ==> Error: trilinos matches multiple packages:
 
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  ffwrpxn trilinos@12.8.1%gcc+boost~debug+hdf5+hypre+metis+mumps~python+shared+suite-sparse+superlu-dist
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  istwe3b trilinos@12.12.1%gcc~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~dtk+epetra+epetraext+exodus+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2+instantiate~instantiate_cmplx~intrepid~intrepid2+metis+ml+muelu+mumps~nox~openmp~pnetcdf~python~rol+sacado~shards+shared~stk+suite-sparse~superlu+superlu-dist+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2
 
-  uvd6dfd trilinos@12.8.1%gcc+boost~debug+hdf5+hypre+metis+mumps~python+shared+suite-sparse+superlu-dist
+  xupifcp trilinos@12.12.1%gcc~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~dtk+epetra+epetraext+exodus+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2+instantiate~instantiate_cmplx~intrepid~intrepid2+metis+ml+muelu+mumps~nox~openmp~pnetcdf~python~rol+sacado~shards+shared~stk+suite-sparse~superlu+superlu-dist+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2
 
 
   ==> Error: You can either:
-      a) Use a more specific spec, or
-      b) use spack uninstall -a to uninstall ALL matching specs.
-
+      a) use a more specific spec, or
+      b) use `spack uninstall --all` to uninstall ALL matching specs.
 
 
-  $ spack uninstall /ffwr
-  ==> The following packages will be uninstalled :
+  $ spack uninstall /istw
+  ==> The following packages will be uninstalled:
 
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  ffwrpxn trilinos@12.8.1%gcc+boost~debug+hdf5+hypre+metis+mumps~python+shared+suite-sparse+superlu-dist
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  istwe3b trilinos@12.12.1%gcc~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~dtk+epetra+epetraext+exodus+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2+instantiate~instantiate_cmplx~intrepid~intrepid2+metis+ml+muelu+mumps~nox~openmp~pnetcdf~python~rol+sacado~shards+shared~stk+suite-sparse~superlu+superlu-dist+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2
 
-
-  ==> Do you want to proceed? [y/n] y
-  ==> Successfully uninstalled trilinos@12.8.1%gcc@4.4.7+boost~debug+hdf5+hypre+metis+mumps~python+shared+suite-sparse+superlu-dist arch=linux-redhat6-x86_64-ffwrpxn
+  ==> Do you want to proceed? [y/N] y
+  ==> Successfully uninstalled trilinos@12.12.1%gcc@5.4.0~alloptpkgs+amesos+amesos2+anasazi+aztec+belos+boost build_type=RelWithDebInfo ~dtk+epetra+epetraext+exodus+fortran~fortrilinos+gtest+hdf5+hypre+ifpack+ifpack2+instantiate~instantiate_cmplx~intrepid~intrepid2+metis+ml+muelu+mumps~nox~openmp~pnetcdf~python~rol+sacado~shards+shared~stk+suite-sparse~superlu+superlu-dist+teuchos+tpetra~x11~xsdkflags~zlib+zoltan+zoltan2 arch=linux-ubuntu16.04-x86_64 /istwe3b
 
 -----------------------------
 Advanced ``spack find`` Usage
@@ -1099,24 +1490,22 @@ already covered in the :ref:`basics-tutorial-install` and
 
 The ``spack find`` command can accept what we call "anonymous specs."
 These are expressions in spec syntax that do not contain a package
-name. For example, ``spack find %intel`` will return every package built
-with the intel compiler, and ``spack find cppflags="-O3"`` will
+name. For example, ``spack find ^mpich`` will return every installed
+package that depends on mpich, and ``spack find cppflags="-O3"`` will
 return every package which was built with ``cppflags="-O3"``.
 
 .. code-block:: console
 
-  $ spack find %intel
-  ==> 1 installed packages.
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-  libelf@0.8.13
-
+  $ spack find ^mpich
+  ==> 9 installed packages.
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  hdf5@1.10.1  hypre@2.12.1  matio@1.5.9  mumps@5.1.1  netcdf@4.4.1.1  netlib-scalapack@2.0.2  parmetis@4.0.3  superlu-dist@5.2.2  trilinos@12.12.1
 
 
-  $ spack find cppflags="-O3"
+  $ spack find cppflags=-O3
   ==> 1 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-  libelf@0.8.12
-
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+  zlib@1.2.8
 
 The ``find`` command can also show which packages were installed
 explicitly (rather than pulled in as a dependency) using the ``-e``
@@ -1128,20 +1517,19 @@ command.
 
   $ spack find -pe
   ==> 10 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-      hdf5@1.10.0-patch1  ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-twppaioxqn6lti4grgopnmhwcq3h2rpw
-      hdf5@1.10.0-patch1  ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-j36yfw25i6gdd3q4vwlupgkpwic4ua6m
-      hdf5@1.10.0-patch1  ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/hdf5-1.10.0-patch1-ezvtnox35albuaxqryuondweyjgeo6es
-      libdwarf@20160507   ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libdwarf-20160507-dtg3tgnp7htccoly26gduqlrgvnwcp5t
-      libdwarf@20160507   ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libdwarf-20160507-yfx6p3g3rkmqvcqbmtb34o6pln7pqvcz
-      libelf@0.8.12       ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.12-ipggckv6i7h44iryzfa4dwdela32a7fy
-      libelf@0.8.12       ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.12-vrv2ttbd34xlfoxy4jwt6qsjrcbalmmw
-      libelf@0.8.13       ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/libelf-0.8.13-csrt4qxfkhjgn5xg3zjpkir7xdnszl2a
-      trilinos@12.8.1     ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/trilinos-12.8.1-uvd6dfd7x4uyvck4awo3r3frudihn4ar
-
-  -- linux-redhat6-x86_64 / intel@16.0.3 --------------------------
-      libelf@0.8.13  ~/spack/opt/spack/linux-redhat6-x86_64/intel-16.0.3/libelf-0.8.13-7wgp32xksatkvw2tbssmehw2t5tnxndj
-
+  -- linux-ubuntu16.04-x86_64 / clang@3.8.0-2ubuntu4 --------------
+      zlib@1.2.11  /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/clang-3.8.0-2ubuntu4/zlib-1.2.11-4pt75q7qq6lygf3hgnona4lyc2uwedul
+
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+      hdf5@1.10.1       /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-pa6oqzfeqzkqkzqr2375fqyt3qggx3tr
+      hdf5@1.10.1       /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-bovz45ms24pmfr7hlckf56bxegfc4rea
+      hdf5@1.10.1       /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/hdf5-1.10.1-e4gz6f2l5ik3ijuk3alwsqplex4tbvin
+      openssl@1.0.2k    /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k-gyxmhgbam26d7y42omb7xrvkjjgmzwio
+      openssl@1.0.2k    /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/openssl-1.0.2k-2woov64m3n4gjtnfp722qcyemzf2qtom
+      trilinos@12.12.1  /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/trilinos-12.12.1-xupifcp5d4f53cobm6g3xzao577uzezs
+      zlib@1.2.8        /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8-bkyl5bhuep6fmhuxzkmhqy25qefjcvzc
+      zlib@1.2.8        /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.8-64mns5mvdacqvlashkf7v6lqrxixhmxu
+      zlib@1.2.11       /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
 
 ---------------------
 Customizing Compilers
@@ -1156,97 +1544,204 @@ compilers`` command is an alias for the command ``spack compiler list``.
 
   $ spack compilers
   ==> Available compilers
-  -- gcc ----------------------------------------------------------
-  gcc@4.4.7
-
-  -- intel --------------------------------------------------------
-  intel@16.0.3  intel@15.0.1  intel@14.0.0  intel@12.1.3  intel@10.0
-  intel@16.0.2  intel@15.0.0  intel@13.1.1  intel@12.1.2  intel@9.1
-  intel@16.0.1  intel@14.0.4  intel@13.1.0  intel@12.1.0
-  intel@16.0.0  intel@14.0.3  intel@13.0.1  intel@12.0.4
-  intel@15.0.4  intel@14.0.2  intel@13.0.0  intel@11.1
-  intel@15.0.3  intel@14.0.1  intel@12.1.5  intel@10.1
-
-  -- pgi ----------------------------------------------------------
-  pgi@16.5-0   pgi@15.7-0   pgi@14.7-0   pgi@13.2-0  pgi@11.10-0  pgi@9.0-4
-  pgi@16.3-0   pgi@15.5-0   pgi@14.3-0   pgi@13.1-1  pgi@11.1-0   pgi@8.0-1
-  pgi@16.1-0   pgi@15.1-0   pgi@13.10-0  pgi@12.8-0  pgi@10.9-0   pgi@7.1-3
-  pgi@15.10-0  pgi@14.10-0  pgi@13.6-0   pgi@12.1-0  pgi@10.2-0   pgi@7.0-6
-
-The compilers are maintained in a YAML file that can be hand-edited
-for special cases. Spack also has tools to add compilers, and
-compilers built with Spack can be added to the configuration.
+  -- clang ubuntu16.04-x86_64 -------------------------------------
+  clang@3.8.0-2ubuntu4  clang@3.7.1-2ubuntu2
+
+  -- gcc ubuntu16.04-x86_64 ---------------------------------------
+  gcc@5.4.0  gcc@4.7
+
+The compilers are maintained in a YAML file. Later in the tutorial you
+will learn how to configure compilers by hand for special cases. Spack
+also has tools to add compilers, and compilers built with Spack can be
+added to the configuration.
 
 .. code-block:: console
 
-  $ spack install --fake gcc@6.1.0
-  ==> Installing gcc
-  ==> gmp is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gmp-6.1.1-uwn4gfdtq3sywy5uf4f7znrh66oybikf
+  $ spack install --use-cache gcc
+  ==> libsigsegv is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libsigsegv-2.11-fypapcprssrj3nstp6njprskeyynsgaz
+  ==> m4 is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/m4-1.4.18-r5envx3kqctwwflhd4qax4ahqtt6x43a
+  ==> pkg-config is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/pkg-config-0.29.2-ae2hwm7q57byfbxtymts55xppqwk7ecj
+  ==> ncurses is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/ncurses-6.0-ukq4tccptm2rxd56d2bumqthnpcjzlez
+  ==> Installing readline
+  ==> Searching for binary cache of readline
+  ==> Finding buildcaches in /home/ubuntu/becker/buildcache/build_cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-matio-1.5.9-3ibrutc6cs7x6ybyt5ni5n6djtq5okm2.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-trilinos-12.12.1-xupifcp5d4f53cobm6g3xzao577uzezs.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-parmetis-4.0.3-qk77g6aiqr3f2hsykg54zzuhlxcpdcmv.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-superlu-dist-5.2.2-65vot2le3ezooz7tj6eveovly725o44x.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-hypre-2.12.1-3psjg2ka2qa26jtgitlil4vglqr67anj.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-mumps-5.1.1-phvk6yhkzqed6gjsbah6dnhlesdclild.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-netcdf-4.4.1.1-rmx4uppnhpv6kq7bh7r46zfqevgdkkgw.spec.yaml
+  ######################################################################## 100.0%
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64-gcc-5.4.0-netlib-scalapack-2.0.2-km7tsbgoyyywonyejkjoojskhc5knz3z.spec.yaml
+  ######################################################################## 100.0%
+  ==> Installing readline from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/readline-7.0/linux-ubuntu16.04-x86_64-gcc-5.4.0-readline-7.0-gizxpch53zv5ufa62a2tb5lalcqgxbuc.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:26:53 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed readline from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/readline-7.0-gizxpch53zv5ufa62a2tb5lalcqgxbuc
+  ==> Installing gdbm
+  ==> Searching for binary cache of gdbm
+  ==> Installing gdbm from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/gdbm-1.13/linux-ubuntu16.04-x86_64-gcc-5.4.0-gdbm-1.13-vdhoris6wdzzb2ykax2hz7qzgizk5h3t.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:26:51 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed gdbm from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/gdbm-1.13-vdhoris6wdzzb2ykax2hz7qzgizk5h3t
+  ==> Installing perl
+  ==> Searching for binary cache of perl
+  ==> Installing perl from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/perl-5.24.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-perl-5.24.1-mfzwy6y5mlbqpqvti4etpe3cgkmxkpi2.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:27:19 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed perl from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/perl-5.24.1-mfzwy6y5mlbqpqvti4etpe3cgkmxkpi2
+  ==> Installing autoconf
+  ==> Searching for binary cache of autoconf
+  ==> Installing autoconf from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/autoconf-2.69/linux-ubuntu16.04-x86_64-gcc-5.4.0-autoconf-2.69-bvabhjiklhi7c5742ixzs7hubhid3ax2.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:27:22 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed autoconf from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/autoconf-2.69-bvabhjiklhi7c5742ixzs7hubhid3ax2
+  ==> Installing automake
+  ==> Searching for binary cache of automake
+  ==> Installing automake from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/automake-1.15.1/linux-ubuntu16.04-x86_64-gcc-5.4.0-automake-1.15.1-kaiefe4j2lsq6b32ncrclmbeoa5z25a5.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:27:21 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed automake from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/automake-1.15.1-kaiefe4j2lsq6b32ncrclmbeoa5z25a5
+  ==> libtool is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/libtool-2.4.6-o2pfwjf44353ajgr42xqtvzyvqsazkgu
+  ==> Installing gmp
+  ==> Searching for binary cache of gmp
+  ==> Installing gmp from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/gmp-6.1.2/linux-ubuntu16.04-x86_64-gcc-5.4.0-gmp-6.1.2-qc4qcfz4monpllc3nqupdo7vwinf73sw.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:12:29 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed gmp from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/gmp-6.1.2-qc4qcfz4monpllc3nqupdo7vwinf73sw
   ==> Installing isl
-  ==> gmp is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gmp-6.1.1-uwn4gfdtq3sywy5uf4f7znrh66oybikf
-  ==> Building isl [Package]
-  ==> Successfully installed isl
-    Fetch: .  Build: 0.19s.  Total: 0.19s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/isl-0.14-hs2w7mjjjaakkmbbv5yvfqf7yyzhorl6
-  ==> Installing mpc
-  ==> gmp is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gmp-6.1.1-uwn4gfdtq3sywy5uf4f7znrh66oybikf
+  ==> Searching for binary cache of isl
+  ==> Installing isl from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/isl-0.18/linux-ubuntu16.04-x86_64-gcc-5.4.0-isl-0.18-vttqoutnsmjpm3ogb52rninksc7hq5ax.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:12:28 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed isl from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/isl-0.18-vttqoutnsmjpm3ogb52rninksc7hq5ax
   ==> Installing mpfr
-  ==> gmp is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gmp-6.1.1-uwn4gfdtq3sywy5uf4f7znrh66oybikf
-  ==> Building mpfr [Package]
-  ==> Successfully installed mpfr
-    Fetch: .  Build: 0.17s.  Total: 0.17s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpfr-3.1.4-7kt5ij437khredfq4bvnyu22t3fmtfvt
-  ==> Building mpc [Package]
-  ==> Successfully installed mpc
-    Fetch: .  Build: 0.28s.  Total: 0.28s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpc-1.0.3-g5taq6lt3zuy5l2jtggi5lctxnl4la5u
-  ==> Installing binutils
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> Installing bison
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> Building bison [Package]
-  ==> Successfully installed bison
-    Fetch: .  Build: 0.12s.  Total: 0.12s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/bison-3.0.4-hkhfysfvq5l6rsns67g2htmkpxauvnwa
-  ==> Installing flex
-  ==> m4 is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/m4-1.4.17-qijdzvhjyybrtwbqm73vykhmkaqro3je
-  ==> bison is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/bison-3.0.4-hkhfysfvq5l6rsns67g2htmkpxauvnwa
-  ==> Building flex [Package]
-  ==> Successfully installed flex
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/flex-2.6.0-qd6d73rdfrozdrsdpimvl4tj7d5ps7qg
-  ==> Building binutils [Package]
-  ==> Successfully installed binutils
-    Fetch: .  Build: 0.11s.  Total: 0.11s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/binutils-2.27-iq2hry3gvaxszmwwbnll7njgdgaek56o
-  ==> mpfr is already installed in ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/mpfr-3.1.4-7kt5ij437khredfq4bvnyu22t3fmtfvt
-  ==> Building gcc [Package]
-  ==> Successfully installed gcc
-    Fetch: .  Build: 0.66s.  Total: 0.66s.
-  [+] ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gcc-6.1.0-j5576zbsot2ydljlthjzhsirsesnogvh
-
-
+  ==> Searching for binary cache of mpfr
+  ==> Installing mpfr from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpfr-3.1.5/linux-ubuntu16.04-x86_64-gcc-5.4.0-mpfr-3.1.5-mdi6irzvxcbemt7yredzr36dvo6ty4sl.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:12:30 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed mpfr from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpfr-3.1.5-mdi6irzvxcbemt7yredzr36dvo6ty4sl
+  ==> Installing mpc
+  ==> Searching for binary cache of mpc
+  ==> Installing mpc from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpc-1.0.3/linux-ubuntu16.04-x86_64-gcc-5.4.0-mpc-1.0.3-tumbpshu5hjxwextoudk5hmic6nspb3z.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:12:29 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed mpc from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/mpc-1.0.3-tumbpshu5hjxwextoudk5hmic6nspb3z
+  ==> zlib is already installed in /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/zlib-1.2.11-5nus6knzumx4ik2yl44jxtgtsl7d54xb
+  ==> Installing gcc
+  ==> Searching for binary cache of gcc
+  ==> Installing gcc from binary cache
+  ==> Fetching file:///home/ubuntu/becker/buildcache/build_cache/linux-ubuntu16.04-x86_64/gcc-5.4.0/gcc-7.2.0/linux-ubuntu16.04-x86_64-gcc-5.4.0-gcc-7.2.0-k3vy57euyeuyvpotwf4wezfmpo3mrtrj.spack
+  ######################################################################## 100.0%
+  gpg: Signature made Sun 12 Nov 2017 10:16:31 PM UTC using RSA key ID 3B7C69B2
+  gpg: Good signature from "sc-tutorial (GPG created for Spack) <becker33@llnl.gov>" [unknown]
+  gpg: WARNING: This key is not certified with a trusted signature!
+  gpg:          There is no indication that the signature belongs to the owner.
+  Primary key fingerprint: 95C7 1787 7AC0 0FFD AA8F  D6E9 9CFA 4A45 3B7C 69B2
+  ==> Relocating package from
+    /home/ubuntu/becker/spack/opt/spack to /home/ubuntu/test/spack/opt/spack.
+  ==> Successfully installed gcc from binary cache
+  [+] /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/gcc-7.2.0-k3vy57euyeuyvpotwf4wezfmpo3mrtrj
 
   $ spack find -p gcc
   ==> 1 installed packages.
-  -- linux-redhat6-x86_64 / gcc@4.4.7 -----------------------------
-      gcc@6.1.0  ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gcc-6.1.0-j5576zbsot2ydljlthjzhsirsesnogvh
-
+  -- linux-ubuntu16.04-x86_64 / gcc@5.4.0 -------------------------
+      gcc@7.2.0  /home/ubuntu/test/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/gcc-7.2.0-k3vy57euyeuyvpotwf4wezfmpo3mrtrj
 
-If we had done a "real" install of gcc, we could add it to our
-configuration now using the `spack compiler add` command, but we would
-also be waiting for it to install. If we run the command now, it will
-return no new compilers.
+We can add gcc to Spack as an available compiler using the ``spack
+compiler add`` command. This will allow future packages to build with
+gcc@7.2.0.
 
 .. code-block:: console
 
-  $ spack compiler add ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gcc-6.1.0-j5576zbsot2ydljlthjzhsirsesnogvh/bin
-  ==> Found no new compilers
+  $ spack compiler add /home/ubuntu/becker/spack/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/gcc-7.2.0-k3vy57euyeuyvpotwf4wezfmpo3mrtrj
+  ==> Added 1 new compiler to /home/ubuntu/.spack/linux/compilers.yaml
+      gcc@7.2.0
+  ==> Compilers are defined in the following files:
+      /home/ubuntu/.spack/linux/compilers.yaml
 
-If we had done a real install, the output would have been as follows:
+We can also remove compilers from our configuration using ``spack compiler remove <compiler_spec>``
 
 .. code-block:: console
 
-  $ spack compiler add ~/spack/opt/spack/linux-redhat6-x86_64/gcc-4.4.7/gcc-6.1.0-j5576zbsot2ydljlthjzhsirsesnogvh/bin
-  ==> Added 1 new compiler to ~/.spack/linux/compilers.yaml
-      gcc@6.1.0
+  $ spack compiler remove gcc@7.2.0
+  ==> Removed compiler gcc@7.2.0