guix build: Add '--quiet'.

Fixes <http://bugs.gnu.org/19772>.
Reported by Andrei Osipov <andrspv@gmail.com>.

* guix/scripts/build.scm (show-help, %options): Add --quiet.
(guix-build): Parameterize 'current-build-output-port' accordingly.
* doc/guix.texi (Invoking guix build): Use it in example.
(Additional Build Options): Document it.

1 files changed, 7 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 0e8e5ad3a9..7945415d7a 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -3836,7 +3836,7 @@ guix build emacs guile
 Similarly, the following command builds all the available packages:
 
 @example
-guix build --keep-going \
+guix build --quiet --keep-going \
   `guix package -A | cut -f1,2 --output-delimiter=@@`
 @end example
 
@@ -4070,6 +4070,12 @@ build}.
 
 @table @code
 
+@item --quiet
+@itemx -q
+Build quietly, without displaying the build log.  Upon completion, the
+build log is kept in @file{/var} (or similar) and can always be
+retrieved using the @option{--log-file} option.
+
 @item --file=@var{file}
 @itemx -f @var{file}