On Fri, Oct 21, 2016 at 05:00:29AM -0400, Jeff King wrote:
> 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
Agreed - tests 110 and 111 in t1300-repo-config.sh fail. After that, "make test"
gives up, losing about 14000 lines of output.
Sorry for the noise,
Cheers ... Duncan.