environment: Add '--emulate-fhs'.

* guix/scripts/environment.scm (show-environment-options-help, %options): Add
'--emulate-fhs'.
(setup-fhs): New procedure.  Setup for the Filesystem Hierarchy Standard (FHS)
container.  Defines and uses FHS-SYMLINKS and LINK-CONTENTS to create FHS
expected directories and creates /etc/ld.so.conf.
(launch-environment): Add 'emulate-fhs?' key and implement it to set $PATH and
generate /etc/ld.so.cache before calling COMMAND.
(launch-environment/container): Add 'emulate-fhs?' and 'setup-hook' keys and
implement them.  Define and use FHS-MAPPINGS, to set up additional bind mounts
in the container to follow FHS expectations.
(guix-environment*): Add glibc-for-fhs to the container packages when
'emulate-fhs?' key is in OPTS.
* doc/guix.texi (Invoking guix shell): Document '--emulate-fhs'.
(Invoking guix environment): Document '--emulate-fhs'.
* tests/guix-environment-container.sh: Add tests for '--emulate-fhs'.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 78ada9c301..dbf4ca9be9 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -108,6 +108,7 @@ Copyright @copyright{} 2022 Justin Veilleux@*
 Copyright @copyright{} 2022 Reily Siegel@*
 Copyright @copyright{} 2022 Simon Streit@*
 Copyright @copyright{} 2022 (@*
+Copyright @copyright{} 2022 John Kehayias@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -6195,6 +6196,27 @@ directory:
 guix shell --container --expose=$HOME=/exchange guile -- guile
 @end example
 
+@cindex file system hierarchy standard (FHS)
+@cindex FHS (file system hierarchy standard)
+@item --emulate-fhs
+@itemx -F
+When used with @option{--container}, emulate a
+@uref{https://refspecs.linuxfoundation.org/fhs.shtml, Filesystem
+Hierarchy Standard (FHS)} configuration within the container, providing
+@file{/bin}, @file{/lib}, and other directories and files specified by
+the FHS.
+
+As Guix deviates from the FHS specification, this
+option sets up the container to more closely mimic that of other
+GNU/Linux distributions.  This is useful for reproducing other
+development environments, testing, and using programs which expect the
+FHS specification to be followed.  With this option, the container will
+include a version of glibc that will read
+@file{/etc/ld.so.cache} within the container for the shared library
+cache (contrary to glibc in regular Guix usage) and set up the
+expected FHS directories: @file{/bin}, @file{/etc}, @file{/lib}, and
+@file{/usr} from the container's profile.
+
 @item --rebuild-cache
 @cindex caching, of profiles
 @cindex caching, in @command{guix shell}
@@ -6614,6 +6636,22 @@ directory:
 guix environment --container --expose=$HOME=/exchange --ad-hoc guile -- guile
 @end example
 
+@item --emulate-fhs
+@item -F
+For containers, emulate a Filesystem Hierarchy Standard (FHS)
+configuration within the container, see
+@uref{https://refspecs.linuxfoundation.org/fhs.shtml, the official
+specification}.  As Guix deviates from the FHS specification, this
+option sets up the container to more closely mimic that of other
+GNU/Linux distributions.  This is useful for reproducing other
+development environments, testing, and using programs which expect the
+FHS specification to be followed.  With this option, the container will
+include a version of @code{glibc} which will read
+@code{/etc/ld.so.cache} within the container for the shared library
+cache (contrary to @code{glibc} in regular Guix usage) and set up the
+expected FHS directories: @code{/bin}, @code{/etc}, @code{/lib}, and
+@code{/usr} from the container's profile.
+
 @end table
 
 @command{guix environment}