07/07: environment: Define 'GUIX_ENVIRONMENT'.

[Ludovic Courtès]

civodul pushed a commit to branch wip-environment
in repository guix.

commit 384b04e8a230b8f43d9372116b32f4235aa9766c
Author: Ludovic Courtès <address@hidden>
Date:   Wed Jul 1 14:39:14 2015 +0200

    environment: Define 'GUIX_ENVIRONMENT'.
    
    * guix/scripts/environment.scm (create-environment): Define 
'GUIX_ENVIRONMENT'.
    * doc/guix.texi (Invoking guix environment): Document it.
    * gnu/system/shadow.scm (default-skeletons): Adjust 'PS1' depending on 
whether
      'GUIX_ENVIRONMENT' is defined.
---
 doc/guix.texi                |   13 +++++++++++++
 gnu/system/shadow.scm        |    8 +++++++-
 guix/scripts/environment.scm |    6 +++++-
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index a35ea2f..fdd8fdf 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4146,6 +4146,19 @@ variables in @file{.bashrc}; instead, they should be 
defined in
 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
 details on Bash start-up files.}.
 
address@hidden GUIX_ENVIRONMENT
address@hidden environment} defines the @code{GUIX_ENVIRONMENT}
+variable in the shell it spaws.  This allows users to, say, define a
+specific prompt for development environments in their @file{.bashrc}
+(@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
+
address@hidden
+if [ -n "$GUIX_ENVIRONMENT" ]
+then
+    export PS1="\u@@\h \w [dev]\$ "
+fi
address@hidden example
+
 Additionally, more than one package may be specified, in which case the
 union of the inputs for the given packages are used.  For example, the
 command below spawns a shell where all of the dependencies of both Guile
diff --git a/gnu/system/shadow.scm b/gnu/system/shadow.scm
index aa97652..ae62292 100644
--- a/gnu/system/shadow.scm
+++ b/gnu/system/shadow.scm
@@ -153,7 +153,13 @@ then
     source /etc/profile
 fi
 
-PS1='address@hidden \\w\\$ '
+# Adjust the prompt depending on whether we're in 'guix environment'.
+if [ -n \"$GUIX_ENVIRONMENT\" ]
+then
+    export PS1='address@hidden \\w\\ [env]$ '
+else
+    export PS1='address@hidden \\w\\$ '
+fi
 alias ls='ls -p --color'
 alias ll='ls -l'\n"))
                       (zlogin (text-file "zlogin" "\
diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 00c4df7..c6cac46 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -78,7 +78,11 @@ search paths."
                          (if (and current (not pure?))
                              (string-append value separator current)
                              value)))))
-            (evaluate-input-search-paths inputs paths)))
+            (evaluate-input-search-paths inputs paths))
+
+  ;; Give users a way to know that they're in 'guix environment', so they can
+  ;; adjust 'PS1' accordingly, for instance.
+  (setenv "GUIX_ENVIRONMENT" "t"))
 
 (define (show-search-paths inputs search-paths pure?)
   "Display SEARCH-PATHS applied to the packages specified by INPUTS, a list of