On Fri, Oct 21, 2016 at 04:50:13PM +1100, Duncan Roe wrote:
> For example, if .git/config has this alias (the sleep is to leave time to
> examine output from ps, &c.):
>
> [alias]
> tryme = "!echo $PWD;sleep 600"
>
> [...]
> 16:42:06$ ps axf|grep -A2 trym[e]
> 2599 pts/4 S+ 0:00 \_ git tryme
> 2601 pts/4 S+ 0:00 \_ /bin/sh -c echo $PWD;sleep 600 echo $PWD;sleep 600
> 2602 pts/4 S+ 0:00 \_ sleep 600
> 16:42:45$ cat /proc/2601/cmdline | xargs -0 -n1 echo
> /bin/sh
> -c
> echo $PWD;sleep 600
> echo $PWD;sleep 600
This duplicated argument is expected and normal. The arguments after "-c
whatever" become positional parameters $0, $1, etc. The actual script
arguments start at "$1", and "$0" is typically the "script name".
So you have to stick some placeholder value in the "$0" slot, so that
the sub-script can find the actual arguments. E.g., try:
sh -c '
for i in "$@"; do
echo "got $i"
done
' one two three
it will print only:
got two
got three
But if you stick a placeholder there, it works:
sh -c '
for i in "$@"; do
echo "got $i"
done
' placeholder one two three
The value of the placeholder does not matter to the shell. But it is
accessible to the script inside via $0:
sh -c '
echo "\$0 = $0"
echo "\$1 = $1"
echo "\$2 = $2"
echo "\$3 = $3"
' placeholder one two three
Since our script does not have a filename, we just stick the script
contents there (which is really just a convention, and one I doubt
anybody is really relying on, but there's no point in breaking it now).
> --- a/run-command.c
> +++ b/run-command.c
> @@ -182,8 +182,8 @@ static const char **prepare_shell_cmd(struct argv_array *out, const char **argv)
> else
> argv_array_pushf(out, "%s \"$@\"", argv[0]);
> }
> -
> - argv_array_pushv(out, argv);
> + else
> + argv_array_pushv(out, argv);
> return out->argv;
> }
Try running "make test" with this. Lots of things break, because we are
not sending the positional parameters to the shell script at all.
If we just cared about the positional parmeters, we _could_ do something
like:
if (argv[0]) {
argv_array_push(out, "sh");
argv_array_pushv(out, argv + 1);
}
That would omit "$0" entirely when we have no positional parameters (and
the shell generally fills in "sh" there itself), and provide a dummy
"sh" value when we need to use it as a placeholder.
But again, there's no real value in breaking the existing convention.
-Peff