Re: Git alias syntax help
- From
- Σταύρος Ντέντος <stdedos@gmail.com>
- Date
- Jan 14, 2020, 23:13 UTC
- Message-ID
- <CAHMHMxVajKxjBweG=mps0gLwE1o8M69DvPb1iUQYgLXx0VO5AA@mail.gmail.com>
- In-Reply-To
- <20200114222802.GC3957260@coredump.intra.peff.net>
On Wed, 15 Jan 2020 at 00:28, Jeff King <peff@peff.net> wrote:
Show 15 quoted lines
>
> On Tue, Jan 14, 2020 at 05:21:20PM +0200, Σταύρος Ντέντος wrote:
>
> > I am having an issue with git-aliases - specifically, the intricacies
> > involved in their syntax.
> >
> > In general, the syntax is confusing to me, especially when it is
> > _wise_ to use quotes inside a `!sh` alias.
> > e.g. which one would be the correct one
> > new = "!f() { : git log ; git log \"${1}@{1}..${1}@{0}\" \"$@\" ; } ; f"
> > new = !f() { : git log ; git log "${1}@{1}..${1}@{0}" "$@" ; } ; f
>
> Only the first one is correct. In addition to the quotes in the second
> one being eaten by the config parser, the unquoted semicolon starts a
> comment.Could somehow the latter "become" the correct option?
Especially in the case of `!sh`:
1) You need to quote everything after `=` sign ("forced" double quotes), then
2) `sh -c` needs another set (singles are most safe here, I think), and
3) If, for some reason, you need to quote further ("$@" would be a
common suspect usually)Apart from the [1] feeling unneeded (the equivalent of Python's `alias_cmd = cfg_line.split()[1]` could be enough), this brings a quoting mess on [3]
Show 35 quoted lines
> > The alias confusing me is more specifically this: > > https://git.wiki.kernel.org/index.php/Aliases#simple_diff_ignoring_line_number_changes > > > > diffsort = !sh -c 'git diff "$@" | grep "^[+-]" | sort --key=1.2 | uniq -u -s1' > > > > The output of: > > $ colordiff -su <(git diffsort HEAD^..HEAD) <(git diffsort HEAD^^..HEAD^) > > Files /dev/fd/63 and /dev/fd/62 are identical > > is a little unexpected, since I know for a fact that one of the > > referced commits is not a code block moved. > > The issue here isn't with Git's alias mechanism, but a quirk of how "sh > -c" works. You can run with GIT_TRACE to see what we're passing to the > shell (though note that your double-quotes don't make it through): > > $ GIT_TRACE=1 git diffsort HEAD^..HEAD > 17:22:47.644542 [pid=3959333] git.c:708 trace: exec: git-diffsort HEAD^..HEAD > 17:22:47.644648 [pid=3959333] run-command.c:663 trace: run_command: git-diffsort HEAD^..HEAD > 17:22:47.645038 [pid=3959333] run-command.c:663 trace: run_command: 'sh -c '\''git diff $@ | grep ^[+-] | sort --key=1.2 | uniq -u -s1'\''' HEAD^..HEAD > 17:22:47.650319 [pid=3959336] git.c:439 trace: built-in: git diff > > The problem is that "sh -c" takes the first non-option argument as $0, > not $1. For example: > > $ sh -c 'echo 0=$0, @=$@' foo bar baz > 0=foo, @=bar baz > > You can add any extra string there to become $0, like: > > diffsort = "!sh -c 'git diff \"$@\" | grep \"^[+-]\" | sort --key=1.2 | uniq -u -s1' --" > > which will do what you want. You can use whatever string you like, since > you know that your "-c" snippet does not ever look at $0. > > -Peff
Thank you very much for a complete explaination of all of this .
Can some of this be documented somewhere? Are they somewhere and I missed them?
If nothing more, a link to this e-mail chain either on the wiki (if https://git.wiki.kernel.org/index.php/Aliases is an official page) or on git-alias help (here https://git-scm.com/book/en/v2/Git-Basics-Git-Aliases or in some "advanced" section, which I cannot find)
If https://git.wiki.kernel.org/index.php/Aliases is an official page, then: was this written for an earlier version? Could it also be updated?
-- Ntentos Stavros