Introduce a SPACK_PYTHON environment variable (#21222)

The SPACK_PYTHON environment variable can be set to a python interpreter to be
used by the spack command.  This allows the spack command itself to use a
consistent and separate interpreter from whatever python might be used for package
building.

1 files changed, 14 insertions, 1 deletions

diff --git a/share/spack/setup-env.fish b/share/spack/setup-env.fish
index 15eff90dd2..190934531d 100755
--- a/share/spack/setup-env.fish
+++ b/share/spack/setup-env.fish
@@ -253,7 +253,7 @@ function match_flag -d "checks all combinations of flags ocurring inside of a st
     set -l _a (string sub -s 2 (string trim "x$argv[1]"))
     set -l _b (string sub -s 2 (string trim "x$argv[2]"))
 
-    if test -z "$_a" || test -z "$_b"
+    if test -z "$_a" or test -z "$_b"
         return 0
     end
 
@@ -668,6 +668,19 @@ set -l sp_source_file (status -f)  # name of current file
 
 
 #
+# Identify and lock the python interpreter
+#
+for cmd in "$SPACK_PYTHON" python3 python python2
+    set -l _sp_python (command -s "$cmd")
+    if test $status -eq 0
+        set -x SPACK_PYTHON $_sp_python
+        break
+    end
+end
+
+
+
+#
 # Find root directory and add bin to path.
 #
 set -l sp_share_dir (realpath (dirname $sp_source_file))