Add support for aliases (#17229)

Add a new config section: `config:aliases`, which is a dictionary mapping aliases
to commands.

For instance:


```yaml
config:
    aliases:
        sp: spec -I
```

will define a new command `sp` that will execute `spec` with the `-I`
argument. 

Aliases cannot override existing commands, and this is ensured with a test.

We cannot currently alias subcommands. Spack will warn about any aliases
containing a space, but will not error, which leaves room for subcommand
aliases in the future.

---------

Co-authored-by: Todd Gamblin <tgamblin@llnl.gov>

1 files changed, 14 insertions, 0 deletions

diff --git a/lib/spack/docs/config_yaml.rst b/lib/spack/docs/config_yaml.rst
index 294f7c3436..d54977beba 100644
--- a/lib/spack/docs/config_yaml.rst
+++ b/lib/spack/docs/config_yaml.rst
@@ -304,3 +304,17 @@ To work properly, this requires your terminal to reset its title after
 Spack has finished its work, otherwise Spack's status information will
 remain in the terminal's title indefinitely. Most terminals should already
 be set up this way and clear Spack's status information.
+
+-----------
+``aliases``
+-----------
+
+Aliases can be used to define new Spack commands. They can be either shortcuts
+for longer commands or include specific arguments for convenience. For instance,
+if users want to use ``spack install``'s ``-v`` argument all the time, they can
+create a new alias called ``inst`` that will always call ``install -v``:
+
+.. code-block:: yaml
+
+   aliases:
+     inst: install -v