guix package: Add optional argument to --search-paths.

* guix/scripts/package.scm (search-path-environment-variables): Add #:kind
  parameter.  Pass it to 'environment-variable-definition'.
  (display-search-paths): Add #:kind parameter and pass it to
  'search-path-environment-variables'.
  (%options): Add an optional parameter for "--search-paths".
  (guix-package)[process-query]: Handle it.
* tests/guix-package-net.sh: Adjust existing test.
* tests/guix-package.sh: Adjust existing tests and add new test.
* doc/guix.texi (Invoking guix package): Document it.

1 files changed, 13 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 8e1bdb6f93..53c9fb2d44 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -1098,7 +1098,7 @@ The difference between @code{--roll-back} and
 not make a zeroth generation, so if a specified generation does not
 exist, the current generation will not be changed.
 
-@item --search-paths
+@item --search-paths[=@var{kind}]
 @cindex search paths
 Report environment variable definitions, in Bash syntax, that may be
 needed in order to use the set of installed packages.  These environment
@@ -1113,6 +1113,18 @@ library are installed in the profile, then @code{--search-paths} will
 suggest setting these variables to @code{@var{profile}/include} and
 @code{@var{profile}/lib}, respectively.
 
+The typical use case is to define these environment variables in the
+shell:
+
+@example
+$ eval `guix package --search-paths`
+@end example
+
+@var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
+meaning that the returned environment variable definitions will either
+be exact settings, or prefixes or suffixes of the current value of these
+variables.  When omitted, @var{kind} defaults to @code{exact}.
+
 @item --profile=@var{profile}
 @itemx -p @var{profile}
 Use @var{profile} instead of the user's default profile.