rev-list: introduce --count option

Add a --count option that, instead of actually listing the commits,
merely counts them.

This is mostly geared towards script use, and to this end it acts
specially when used with --left-right: it outputs the left and right
counts separately.  Previously, scripts would have to run a shell loop
or small inline script over to achieve the same.  (Without
--left-right, a simple |wc -l does the job.)

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index b9fb7a86bd..066ade9fce 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -98,6 +98,15 @@ you would get an output like this:
 This implies the '--topo-order' option by default, but the
 '--date-order' option may also be specified.
 
+ifdef::git-rev-list[]
+--count::
+	Print a number stating how many commits would have been
+	listed, and suppress all other output.  When used together
+	with '--left-right', instead print the counts for left and
+	right commits, separated by a tab.
+endif::git-rev-list[]
+
+
 ifndef::git-rev-list[]
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