system: Factorize bashrc default configuration.

This factorizes out the remaining bashrc bits from /etc/skel/.bashrc to a the
template used for both /etc/bashrc on Guix System and ~/.bashrc for
home-bash-service-type.

Rationale: The use of /etc/skel introduce state: the file is only copied
originally when the user account is created, and never (automatically)
refreshed again.

* gnu/system.scm (operating-system-etc-service):
<profile>: Guard against souring /etc/bashrc in non-interactive, SSH case.
<bashrc>: Use %default-bashrc, having migrated the remaining definitions to...
* gnu/system/shadow.scm (%default-bashrc): ... here.  Factorize aliases to...
* gnu/services.scm (%default-bash-aliases): ... here.
(%default-bashrc-d-aliases): New variable.
(%default-etc-bashrc-d-files): Include it in the default configuration.
* gnu/services/base.scm (%base-services): Register etc-bashrc-d-service-type.
* gnu/home/services/shells.scm (add-bash-configuration): Do not set PS1, now
part of %default-bashrc.
(home-bash-configuration) [guix-defaults?]: Update doc.
[aliases]: Set %default-bash-aliases as the default value.  Update doc.
* doc/guix.texi (Shells Home Services): Update documentation.
(Service Reference): Update example.

Change-Id: I340c614983a78fd20a9c4a9705e7fc542ae9b513

1 files changed, 21 insertions, 2 deletions

diff --git a/gnu/services.scm b/gnu/services.scm
index 5dbda176b80..159d357c3e7 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -125,6 +125,7 @@
             etc-profile-d-service-type
             etc-bashrc-d-service-type
             %default-etc-bashrc-d-files
+            %default-bash-aliases
             etc-directory
             privileged-program-service-type
             setuid-program-service-type ; deprecated
@@ -993,9 +994,27 @@ log in.")))
 (define files->bashrc-d-directory
   (make-files->etc-directory "bashrc.d"))
 
+;;; Use an alist to be compatible with <home-bash-configuration>.
+(define %default-bash-aliases
+  '(("ls" . "ls -p --color=auto")
+    ("ll" . "ls -l")
+    ("grep" . "grep --color=auto")
+    ("ip" . "ip -color=auto")))
+
+;;; ... but avoid the full blown bash-serialize-aliases, which depends on
+;;; other 'guix home' definitions such as `shell-double-quote'.
+(define %default-bashrc-d-aliases
+  (plain-file "aliases.sh"
+              (string-join
+               (map (match-lambda
+                      ((alias . value)
+                       (format #f "~a=~s~%" alias value)))
+                    %default-bash-aliases)
+               "")))
+
 (define %default-etc-bashrc-d-files
-  (list (file-append bash-completion
-                     "/etc/profile.d/bash_completion.sh")))
+  (list (file-append bash-completion "/etc/profile.d/bash_completion.sh")
+        %default-bashrc-d-aliases))
 
 (define etc-bashrc-d-service-type
   (service-type