Create 'git gc' to perform common maintenance operations.

Junio asked for a 'git gc' utility which users can execute on a
regular basis to perform basic repository actions such as:

 * pack-refs --prune
 * reflog expire
 * repack -a -d
 * prune
 * rerere gc

So here is a command which does exactly that.  The parameters fed
to reflog's expire subcommand can be chosen by the user by setting
configuration options in .git/config (or ~/.gitconfig), as users may
want different expiration windows for each repository but shouldn't
be bothered to remember what they are all of the time.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 64 insertions, 0 deletions

diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
new file mode 100644
index 0000000000..73d78c15e8
--- /dev/null
+++ b/Documentation/git-gc.txt
@@ -0,0 +1,64 @@
+git-gc(1)
+=========
+
+NAME
+----
+git-gc - Cleanup unnecessary files and optimize the local repository
+
+
+SYNOPSIS
+--------
+'git-gc'
+
+DESCRIPTION
+-----------
+Runs a number of housekeeping tasks within the current repository,
+such as compressing file revisions (to reduce disk space and increase
+performance) and removing unreachable objects which may have been
+created from prior invocations of gitlink:git-add[1].
+
+Users are encouraged to run this task on a regular basis within
+each repository to maintain good disk space utilization and good
+operating performance.
+
+Configuration
+-------------
+
+The optional configuration variable 'gc.reflogExpire' can be
+set to indicate how long historical entries within each branch's
+reflog should remain available in this repository.  The setting is
+expressed as a length of time, for example '90 days' or '3 months'.
+It defaults to '90 days'.
+
+The optional configuration variable 'gc.reflogExpireUnreachable'
+can be set to indicate how long historical reflog entries which
+are not part of the current branch should remain available in
+this repository.  These types of entries are generally created as
+a result of using `git commit \--amend` or `git rebase` and are the
+commits prior to the amend or rebase occuring.  Since these changes
+are not part of the current project most users will want to expire
+them sooner.  This option defaults to '30 days'.
+
+The optional configuration variable 'gc.rerereresolved' indicates
+how long records of conflicted merge you resolved earlier are
+kept.  This defaults to 60 days.
+
+The optional configuration variable 'gc.rerereunresolved' indicates
+how long records of conflicted merge you have not resolved are
+kept.  This defaults to 15 days.
+
+
+See Also
+--------
+gitlink:git-prune[1]
+gitlink:git-reflog[1]
+gitlink:git-repack[1]
+gitlink:git-rerere[1]
+
+Author
+------
+Written by Shawn O. Pearce <spearce@spearce.org>
+
+GIT
+---
+Part of the gitlink:git[7] suite