remove #!interpreter line from shell libraries

In a shell snippet meant to be sourced by other shell scripts, an
opening #! line does more harm than good.

The harm:

 - When the shell library is sourced, the interpreter and options from
   the #! line are not used.  Specifying a particular shell can
   confuse the reader into thinking it is safe for the shell library
   to rely on idiosyncrasies of that shell.

 - Using #! instead of a plain comment drops a helpful visual clue
   that this is a shell library and not a self-contained script.

 - Tools such as lintian can use a #! line to tell when an
   installation script has failed by forgetting to set a script
   executable.  This check does not work if shell libraries also start
   with a #! line.

The good:

 - Text editors notice the #! line and use it for syntax highlighting
   if you try to edit the installed scripts (without ".sh" suffix) in
   place.

The use of the #! for file type detection is not needed because Git's
shell libraries are meant to be edited in source form (with ".sh"
suffix).  Replace the opening #! lines with comments.

This involves tweaking the test harness's valgrind support to find
shell libraries by looking for "# " in the first line instead of "#!"
(see v1.7.6-rc3~7, 2011-06-17).

Suggested by Russ Allbery through lintian.  Thanks to Jeff King and
Clemens Buchacher for further analysis.

Tested by searching for non-executable scripts with #! line:

	find . -name .git -prune -o -type f -not -executable |
	while read file
	do
		read line <"$file"
		case $line in
		'#!'*)
			echo "$file"
			;;
		esac
	done

The only remaining scripts found are templates for shell scripts
(unimplemented.sh, wrap-for-bin.sh) and sample input used in tests
(t/t4034/perl/{pre,post}).

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/t/test-lib.sh b/t/test-lib.sh
index c306bd0..c3e07b9 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -573,11 +573,9 @@ then
 
 	make_valgrind_symlink () {
 		# handle only executables, unless they are shell libraries that
-		# need to be in the exec-path.  We will just use "#!" as a
-		# guess for a shell-script, since we have no idea what the user
-		# may have configured as the shell path.
+		# need to be in the exec-path.
 		test -x "$1" ||
-		test "#!" = "$(head -c 2 <"$1")" ||
+		test "# " = "$(head -c 2 <"$1")" ||
 		return;
 
 		base=$(basename "$1")