git branch command is incompatible with bash

git branch command is incompatible with bash

[Anatol Rudolph]

Hello!

I hope posting this to this mailing list is okay, this is the first ever
mail that I submit to a technical mailing list. 

When using the git branch command, git uses a '*' to denote the current
branch. Therefore, in bash this:

	$ branchName=$(git branch -q)
	$ echo $branchName

produces a directory listing, because the '*' is interpreded by the
shell. 

While an (unwieldly) workaround exists:

	$ branchName=$(git symbolic-ref -q HEAD)                                                                            
	$ branchName=${branch##refs/heads/}

it would still be nice, if there were a --current flag, that returned
only the current branch name, omitting the star:

	$ branchName=$(git branch --current -q)
	$ echo $branchName
	master

Re: git branch command is incompatible with bash

[Johannes Sixt]

Am 27.07.2015 um 14:12 schrieb Anatol Rudolph:
> When using the git branch command, git uses a '*' to denote the current
> branch. Therefore, in bash this:
>
> 	$ branchName=$(git branch -q)
> 	$ echo $branchName
>
> produces a directory listing, because the '*' is interpreded by the
> shell.

Of course. You would write the last line as

   echo "$branchName"

These are shell fundamentals.

> While an (unwieldly) workaround exists:
>
> 	$ branchName=$(git symbolic-ref -q HEAD)
> 	$ branchName=${branch##refs/heads/}

If you want to do that in a script, this is not a work-around, but it is 
how you should do it. But you may want to use option --short to save the 
second line.

> it would still be nice, if there were a --current flag, that returned
> only the current branch name, omitting the star:
>
> 	$ branchName=$(git branch --current -q)
> 	$ echo $branchName
> 	master

Try

   branchName=$(git rev-parse --abbrev-ref HEAD)

-- Hannes

Re: git branch command is incompatible with bash

[Junio C Hamano]

Johannes Sixt <j6t@kdbg.org> writes:

> Try
>
>   branchName=$(git rev-parse --abbrev-ref HEAD)

Hmm, interesting.

    $ git checkout --orphan notyet
    $ git rev-parse --abbrev-ref HEAD
    $ git symbolic-ref --short HEAD

Re: git branch command is incompatible with bash

[Johannes Sixt]

Am 27.07.2015 um 23:49 schrieb Junio C Hamano:
> Johannes Sixt <j6t@kdbg.org> writes:
>
>> Try
>>
>>    branchName=$(git rev-parse --abbrev-ref HEAD)
>
> Hmm, interesting.
>
>      $ git checkout --orphan notyet
>      $ git rev-parse --abbrev-ref HEAD
>      $ git symbolic-ref --short HEAD
>

Please don't scare newcomers with these corner cases ;-)

I see this:

$ git rev-parse --abbrev-ref HEAD
HEAD
fatal: ambiguous argument 'HEAD': unknown revision or path not in the 
working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
$ git symbolic-ref --short HEAD
notyet

Are you trying to say that the result of 'rev-parse --abbrev-ref HEAD' 
is suboptimal and that of 'symbolic-ref --short HEAD' is OK?

-- Hannes

Re: git branch command is incompatible with bash

[Jakub Narębski]

W dniu 2015-07-28 o 09:28, Johannes Sixt pisze:
> Am 27.07.2015 um 23:49 schrieb Junio C Hamano:
>> Johannes Sixt <j6t@kdbg.org> writes:
>>
>>> Try
>>>
>>>    branchName=$(git rev-parse --abbrev-ref HEAD)
>>
>> Hmm, interesting.
>>
>>      $ git checkout --orphan notyet
>>      $ git rev-parse --abbrev-ref HEAD
>>      $ git symbolic-ref --short HEAD
>>
>
> Please don't scare newcomers with these corner cases ;-)

:-P

Yet another corner case:

   $ git checkout origin/master # or v1.0.0
   $ git rev-parse --abbrev-ref HEAD
   $ git symbolic-ref --short HEAD

> I see this:
>
> $ git rev-parse --abbrev-ref HEAD
> HEAD
> fatal: ambiguous argument 'HEAD': unknown revision or path not in the
> working tree.
> Use '--' to separate paths from revisions, like this:
> 'git <command> [<revision>...] -- [<file>...]'

Errr... this error message is errorneous (well, at least somewhat
misleading). Git should know that HEAD is not a path, and that
--abbrev-ref doe not need no revision.

> $ git symbolic-ref --short HEAD
> notyet
>
> Are you trying to say that the result of 'rev-parse --abbrev-ref HEAD'
> is suboptimal and that of 'symbolic-ref --short HEAD' is OK?

-- 
Jakub Narębski

Re: git branch command is incompatible with bash

[Junio C Hamano]

Johannes Sixt <j6t@kdbg.org> writes:

> Are you trying to say that the result of 'rev-parse --abbrev-ref HEAD'
> is suboptimal and that of 'symbolic-ref --short HEAD' is OK?

My "Interesting" was primarily about that I wasn't aware of the
"--abbrev-ref" option.

Yes, I am sure some time ago I accepted a patch to add it, but I
simply do not see the point, especially because the "--short" option
to symbolic-ref feels much more superiour.  "What branch am I on?"
is about symbolic refs, rev-parse is about revisions.

I can see that "symbolic-ref --short" is much newer than the other
one, so addition of "--abbrev-ref" to "rev-parse" may have been a
mistake made while being desperate (i.e. not having a way to do so
with plumbing, we wanted "some" way to do so and chose poorly).

Re: git branch command is incompatible with bash

[Jeff King]

On Tue, Jul 28, 2015 at 08:23:40AM -0700, Junio C Hamano wrote:

> I can see that "symbolic-ref --short" is much newer than the other
> one, so addition of "--abbrev-ref" to "rev-parse" may have been a
> mistake made while being desperate (i.e. not having a way to do so
> with plumbing, we wanted "some" way to do so and chose poorly).

I think --abbrev-ref can handle much more than just shortening symrefs,
though:

E.g. resolving other symbolic names:

  $ git rev-parse --abbrev-ref @{u}
  origin/master

Or resolving any arbitrary name you happen to have:

  $ git rev-parse --abbrev-ref refs/heads/master
  master

Even ones that aren't fully qualified (which would be tough to do with
simple pattern substitution):

  $ git rev-parse --abbrev-ref remotes/origin/master
  origin/master

Or handling ambiguities during abbreviation:

  $ git tag master
  $ git rev-parse --abbrev-ref HEAD
  heads/master

-Peff

Re: git branch command is incompatible with bash

[Johannes Sixt]

Am 28.07.2015 um 17:23 schrieb Junio C Hamano:
> Johannes Sixt <j6t@kdbg.org> writes:
>
>> Are you trying to say that the result of 'rev-parse --abbrev-ref HEAD'
>> is suboptimal and that of 'symbolic-ref --short HEAD' is OK?
>
> My "Interesting" was primarily about that I wasn't aware of the
> "--abbrev-ref" option.
>
> Yes, I am sure some time ago I accepted a patch to add it, but I
> simply do not see the point, especially because the "--short" option
> to symbolic-ref feels much more superiour.  "What branch am I on?"
> is about symbolic refs, rev-parse is about revisions.
>
> I can see that "symbolic-ref --short" is much newer than the other
> one, so addition of "--abbrev-ref" to "rev-parse" may have been a
> mistake made while being desperate (i.e. not having a way to do so
> with plumbing, we wanted "some" way to do so and chose poorly).

Heh. Originially, I was about to suggest

    git symbolic-ref -q --short HEAD || git rev-parse --abbrev HEAD

in order to handle the detached HEAD case by printing the abbreviated 
commit name, only to learn that this doesn't do what I expected. Looking 
at the man page of rev-parse, I discovered --abbrev-ref. And learned 
that I actually should have used --short instead of --abbrev in the 
above rev-parse command.

Confusing...

-- Hannes

Re: git branch command is incompatible with bash

[Scott Schmit]

On Tue, Jul 28, 2015 at 08:23:40AM -0700, Junio C Hamano wrote:
> Johannes Sixt <j6t@kdbg.org> writes:
> > Are you trying to say that the result of 'rev-parse --abbrev-ref HEAD'
> > is suboptimal and that of 'symbolic-ref --short HEAD' is OK?
> 
> My "Interesting" was primarily about that I wasn't aware of the
> "--abbrev-ref" option.
> 
> Yes, I am sure some time ago I accepted a patch to add it, but I
> simply do not see the point, especially because the "--short" option
> to symbolic-ref feels much more superiour.  "What branch am I on?"
> is about symbolic refs, rev-parse is about revisions.

Sometimes my question is "what branch am I on?" -- in which case
symbolic-ref is adequate.

Other times, my question is "where am I/what did I check out?" which is
usually a branch, sometimes a tag, and sometimes a commit hash.  We
don't have a one-stop-shop command to answer that question in all cases,
which is unfortunate.

git status answers, but that's not plumbing.  git-prompt manages to do a
fairly good job, but the logic is by no means straightforward.

-- 
Scott Schmit