threads / discuss / 51610

$> git branch splat response considered harmful

Subject: $> git branch splat response considered harmful

## tl;dr

6 messages between Aug 8, 2019 and Aug 9, 2019.

replies: 5people: 6as markdown or json

jim.cromie@gmail.com· Aug 8, 2019, 21:08 UTC · lore
fwiw,
jimc@frodo:~/prj-1/capnproto.git$ git branch -l
* master

I find the splat in the response unhelpful when wrapped in shell for loop, the splat expands into everything in current directory

jimc@frodo:~/prj-1/capnproto.git$ for b in `git branch -l`; do echo $b; done appveyor.yml c++ CMakeLists.txt CONTRIBUTORS ...

it would be nice if some flag combo would suppress that splat. save me from fugly brittle sh $IFS fiddlery and incomplete workarounds

git branch -l  # no splat
  master
git branch # splat ok for back-compat (if you think it necessary)
  * master

it appears that by convention, checked out branch is both 1st in list, and splatted, perhaps _DIRTY_, JUNK, or maybe "" would be good 1st line of response if not on a branch ?

also, I found no mention of the splat in the man page.
Bryan Turner· Aug 8, 2019, 21:20 UTC · re: jim.cromie@gmail.com · lore

Re: $> git branch splat response considered harmful

On Thu, Aug 8, 2019 at 2:08 PM <jim.cromie@gmail.com> wrote:
Show 19 quoted lines
>
> fwiw,
>
> jimc@frodo:~/prj-1/capnproto.git$ git branch -l
> * master
>
> I find the splat in the response unhelpful
> when wrapped in shell for loop, the splat expands into everything in
> current directory
>
> jimc@frodo:~/prj-1/capnproto.git$ for b in `git branch -l`; do echo $b; done
> appveyor.yml
> c++
> CMakeLists.txt
> CONTRIBUTORS
> ...
>
> it would be nice if some flag combo would suppress that splat.
> save me from fugly brittle sh $IFS fiddlery and incomplete workarounds

Have you tried "git for-each-ref --format="%(refname:short)" refs/heads/"? That's going to provide short names for branches without any indicator for the default branch, and without any special ordering.

Emily Shaffer· Aug 8, 2019, 21:28 UTC · re: Bryan Turner · lore

Re: $> git branch splat response considered harmful

On Thu, Aug 8, 2019 at 2:20 PM Bryan Turner <bturner@atlassian.com> wrote:
Show 26 quoted lines
>
> On Thu, Aug 8, 2019 at 2:08 PM <jim.cromie@gmail.com> wrote:
> >
> > fwiw,
> >
> > jimc@frodo:~/prj-1/capnproto.git$ git branch -l
> > * master
> >
> > I find the splat in the response unhelpful
> > when wrapped in shell for loop, the splat expands into everything in
> > current directory
> >
> > jimc@frodo:~/prj-1/capnproto.git$ for b in `git branch -l`; do echo $b; done
> > appveyor.yml
> > c++
> > CMakeLists.txt
> > CONTRIBUTORS
> > ...
> >
> > it would be nice if some flag combo would suppress that splat.
> > save me from fugly brittle sh $IFS fiddlery and incomplete workarounds
>
> Have you tried "git for-each-ref --format="%(refname:short)"
> refs/heads/"? That's going to provide short names for branches without
> any indicator for the default branch, and without any special
> ordering.

More generally, I think you should take a look at `git help git` and check out the difference between "porcelain" and "plumbing" commands. The former, of which `git branch` is one, are intended for interactive use and not really meant for scripting or piping. You can usually come up with an equivalent from the plumbing commands, which Bryan has suggested for you with `git for-each-ref`. Git project tries very hard to maintain output format of the plumbing commands so as to not break folks' scripts, but such promises aren't usually made for porcelain commands.

-- 
Emily Shaffer
SZEDER Gábor· Aug 8, 2019, 21:30 UTC · re: jim.cromie@gmail.com · lore

Re: $> git branch splat response considered harmful

On Thu, Aug 08, 2019 at 03:08:06PM -0600, jim.cromie@gmail.com wrote:
Show 18 quoted lines
> fwiw,
> 
> jimc@frodo:~/prj-1/capnproto.git$ git branch -l
> * master
> 
> I find the splat in the response unhelpful
> when wrapped in shell for loop, the splat expands into everything in
> current directory
> 
> jimc@frodo:~/prj-1/capnproto.git$ for b in `git branch -l`; do echo $b; done
> appveyor.yml
> c++
> CMakeLists.txt
> CONTRIBUTORS
> ...
> 
> it would be nice if some flag combo would suppress that splat.
> save me from fugly brittle sh $IFS fiddlery and incomplete workarounds

'git branch' is not intended for scripting, try 'git for-each-ref' instead. The equivalent command should be:

  git for-each-ref --format='%(refname:strip=2)' refs/heads/
> also, I found no mention of the splat in the man page.
It's in the first sentence of the description :)
  If --list is given, or if there are no non-option arguments, existing
  branches are listed; the current branch will be highlighted in green
  and marked with an asterisk.
Junio C Hamano· Aug 8, 2019, 21:46 UTC · re: Emily Shaffer · lore

Re: $> git branch splat response considered harmful

Emily Shaffer <emilyshaffer@google.com> writes:
Show 9 quoted lines
> More generally, I think you should take a look at `git help git` and
> check out the difference between "porcelain" and "plumbing" commands.
> The former, of which `git branch` is one, are intended for interactive
> use and not really meant for scripting or piping. You can usually come
> up with an equivalent from the plumbing commands, which Bryan has
> suggested for you with `git for-each-ref`.  Git project tries very
> hard to maintain output format of the plumbing commands so as to not
> break folks' scripts, but such promises aren't usually made for
> porcelain commands.
Thanks for a detailed response.

Git project promises that output format of the Porcelain commands is subject to change, in order to support human eyeballs better.

Unless documented otherwise (e.g. "git status --porcelain"), it is unwise to try parsing porcelain output---your script may break any time and you get to keep both halves.

That is not the same as saying "do not script using Porcelain". Sending the output directly to the end user (e.g. compute the revision range in your script that finally calls "git log" using that computed revision range) is perfectly fine.

Thanks.
Philip Oakley· Aug 9, 2019, 18:01 UTC · re: Emily Shaffer · lore

Re: $> git branch splat response considered harmful

On 08/08/2019 22:28, Emily Shaffer wrote:
Show 34 quoted lines
> On Thu, Aug 8, 2019 at 2:20 PM Bryan Turner <bturner@atlassian.com> wrote:
>> On Thu, Aug 8, 2019 at 2:08 PM <jim.cromie@gmail.com> wrote:
>>> fwiw,
>>>
>>> jimc@frodo:~/prj-1/capnproto.git$ git branch -l
>>> * master
>>>
>>> I find the splat in the response unhelpful
>>> when wrapped in shell for loop, the splat expands into everything in
>>> current directory
>>>
>>> jimc@frodo:~/prj-1/capnproto.git$ for b in `git branch -l`; do echo $b; done
>>> appveyor.yml
>>> c++
>>> CMakeLists.txt
>>> CONTRIBUTORS
>>> ...
>>>
>>> it would be nice if some flag combo would suppress that splat.
>>> save me from fugly brittle sh $IFS fiddlery and incomplete workarounds
>> Have you tried "git for-each-ref --format="%(refname:short)"
>> refs/heads/"? That's going to provide short names for branches without
>> any indicator for the default branch, and without any special
>> ordering.
> More generally, I think you should take a look at `git help git` and
> check out the difference between "porcelain" and "plumbing" commands.
> The former, of which `git branch` is one, are intended for interactive
> use and not really meant for scripting or piping. You can usually come
> up with an equivalent from the plumbing commands, which Bryan has
> suggested for you with `git for-each-ref`.  Git project tries very
> hard to maintain output format of the plumbing commands so as to not
> break folks' scripts, but such promises aren't usually made for
> porcelain commands.
>

I think this (the broad Q&A) also suggests that the porcelain command documentation could be more helpful for pointing to the appropriate plumbing commands for these scripting issues (and it could reduce list noise..). -- Philip

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