Re: [PATCH v6] [GSOC] trailer: add new trailer.<token>.cmd config option

>
> On Sun, Apr 4, 2021 at 7:44 AM ZheNing Hu <adlternative@gmail.com> wrote:
>
> > This may be an off-topic question:
> > I wanted to use `shortlog -s` instead of the document example,
> > But I found a very strange place:
> > Here we have two shell scripts:
> >
> > $ cat ~/bin/gcount
> > #!/bin/sh
> > if test "$1" != ""
>
> It's better to use `test -n "$1"` instead of `test "$1" != ""`.
>
> > then
> > git log -1 --author="$1"
> > else
> > echo "hello there"
> > fi
> >
> > cat ~/bin/gcount2
> > #!/bin/sh
> > if test "$1" != ""
> > then
> > git shortlog -1 --author="$1"
> > else
> > echo "hello there"
> > fi
> >
> > If I use them in the terminal, there is no problem with them,
> >
> > $ ~/bin/gcount gitster
> > commit 142430338477d9d1bb25be66267225fb58498d92
> > (interpret-trailers-command-arg, abc5b)
> > Author: Junio C Hamano <gitster@pobox.com>
> > Date:   Mon Mar 22 14:00:00 2021 -0700
> >
> >     The second batch
> >
> >     Signed-off-by: Junio C Hamano <gitster@pobox.com>
> >
> > $ ~/bin/gcount2 gitster
> > Junio C Hamano (1):
> >       The second batch
> >
> > if I use .cmd to run these scripts, the situation is totally different:
> >
> > $ git config -l | grep trailer
> > trailer.cnt.ifexists=add
> > trailer.cnt.key=Cnt:
> > trailer.cnt.cmd=~/bin/gcount
>
> The script/command used in ".cmd" or ".command" should really return a
> short string with no newline or line feed char in it. Here your script
> can return multiple lines which could mess things up and be difficult
> to understand.
>

> > $ git interpret-trailers --trailer="cnt:gitster" <<EOF
> > EOF
> >
> > Cnt: hello there
> > Cnt: commit 142430338477d9d1bb25be66267225fb58498d92
> > Author: Junio C Hamano <gitster@pobox.com>
> > Date:   Mon Mar 22 14:00:00 2021 -0700
> >
> >     The second batch
> >
> >     Signed-off-by: Junio C Hamano <gitster@pobox.com>
> >
> > And if I turn to use gcount2:
> > $ git config trailer.cnt.cmd "~/bin/gcount2"
> > $ git interpret-trailers --trailer="cnt:gitster" <<EOF
> > EOF
> >
> > Cnt: hello there
> > Cnt:
> >
> > It looks like `shortlog` does not write to standard output.
>
> In shortlog's doc there is:
>
> "If no revisions are passed on the command line and either standard
> input is not a terminal or there is no current branch, git shortlog
> will output a summary of the log read from standard input, without
> reference to the current repository."
>
> I guess that's what's happening here.
>

> > Note that in `short_log.c`, log will be output to `log->file`.
> > Does it make the above behavior different?
> > Is there a good solution?
>
> I would try to pass a revision on the command line.