[PATCH] pre-commit.sample: don't print incidental SHA1

[PATCH] pre-commit.sample: don't print incidental SHA1

[Jim Meyering]

Make the sample pre-commit hook script discard
all git-rev-parse output, not just stderr.
Otherwise, it would print an SHA1.

Signed-off-by: Jim Meyering <meyering@redhat.com>
---
[this patch applies at least to "next"]
I enabled the sample pre-commit hook and was surprised to
see new output with every commit.  It was due to that script's
use of git-rev-parse.

Also, I noticed the use of "git-hyphen" git-rev-parse.
Perhaps that hyphen has been left in deliberately,
for portability to very old versions of git?

While the 800+ uses of "git rev-parse" far outnumber uses of the
two-hyphen version, this is far from being the only use in code
(this is on the "next" branch):

  $ git grep -l git-rev-parse|grep -vE 'Docu|command-list|\.giti'
  contrib/emacs/git.el
  contrib/examples/git-revert.sh
  git-archimport.perl
  git-cvsexportcommit.perl
  git-cvsimport.perl
  git-submodule.sh
  gitweb/gitweb.perl
  perl/Git.pm
  templates/hooks--pre-commit.sample


 templates/hooks--pre-commit.sample |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/templates/hooks--pre-commit.sample b/templates/hooks--pre-commit.sample
index 0e49279..0ba6207 100755
--- a/templates/hooks--pre-commit.sample
+++ b/templates/hooks--pre-commit.sample
@@ -7,7 +7,7 @@
 #
 # To enable this hook, rename this file to "pre-commit".

-if git-rev-parse --verify HEAD 2>/dev/null
+if git-rev-parse --verify HEAD >/dev/null 2>&1
 then
 	against=HEAD
 else
-- 
1.6.3.1.83.g37eb7

Re: [PATCH] pre-commit.sample: don't print incidental SHA1

[Junio C Hamano]

Jim Meyering <jim@meyering.net> writes:

> I enabled the sample pre-commit hook and was surprised to
> see new output with every commit.  It was due to that script's
> use of git-rev-parse.

Thanks.  I am half surprised that nobody has complained about this,
because the problem has been there since early 2006, and am half
unsurprised because I have long suspected that nobody would be using
pre-commit hook in real life.

> Also, I noticed the use of "git-hyphen" git-rev-parse.
> Perhaps that hyphen has been left in deliberately,
> for portability to very old versions of git?

Sample hooks do use features available only in the version of git that
ships them; we do not strive to retain such a portability in that sense.

The hook scripts are special in that they are invoked in an environment in
which the git subcommands in their dashed form are always available on its
$PATH.  People tend to learn by looking at examples, so it is a good idea
to change them to use the new, separate subcommand, form to set examples.

But that is obviously a much wider patch, so let's make that a separate
issue.