v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Steffen Nurpmeso]

Hello again,

yah, sorry, i'm back again..
I try to find a way to find the name of the current branch in an
automated way, because i need to ensure that a commit happens on
it and no other branch.  Now the problem arises that the commit
ref at the time of that commit maybe shared in between several
different branches, but no more thereafter, of course:

  ?0[steffen@wales ]$ git branch|grep '^*'
  * stable/v14.9
  ?0[steffen@wales ]$ git name-rev --name-only HEAD
  stable/v14.8

Is there another way except looking into .git/HEAD or using sed(1)
on the output of `branch' to find the right name?
Thank you.
Ciao!

--steffen

Re: v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Bryan Turner]

On Tue, Sep 20, 2016 at 9:23 AM, Steffen Nurpmeso <steffen@sdaoden.eu> wrote:
> Hello again,
>
> yah, sorry, i'm back again..
> I try to find a way to find the name of the current branch in an
> automated way, because i need to ensure that a commit happens on
> it and no other branch.  Now the problem arises that the commit
> ref at the time of that commit maybe shared in between several
> different branches, but no more thereafter, of course:
>
>   ?0[steffen@wales ]$ git branch|grep '^*'
>   * stable/v14.9
>   ?0[steffen@wales ]$ git name-rev --name-only HEAD
>   stable/v14.8
>
> Is there another way except looking into .git/HEAD or using sed(1)
> on the output of `branch' to find the right name?

Have you tried "git symbolic-ref HEAD"?

$ git symbolic-ref HEAD
refs/heads/master

If you don't want the fully-qualified ref, you can add --short:

$ git symbolic-ref --short HEAD
master

> Thank you.
> Ciao!
>
> --steffen

Re: v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Steffen Nurpmeso]

Hey.

Bryan Turner <bturner@atlassian.com> wrote:
 |On Tue, Sep 20, 2016 at 9:23 AM, Steffen Nurpmeso <steffen@sdaoden.eu> \
 |wrote:
 |> yah, sorry, i'm back again..
 |> I try to find a way to find the name of the current branch in an
 |> automated way, because i need to ensure that a commit happens on
 |> it and no other branch.  Now the problem arises that the commit
 |> ref at the time of that commit maybe shared in between several
 |> different branches, but no more thereafter, of course:
 |>
 |>   ?0[steffen@wales ]$ git branch|grep '^*'
 |>   * stable/v14.9
 |>   ?0[steffen@wales ]$ git name-rev --name-only HEAD
 |>   stable/v14.8
 |>
 |> Is there another way except looking into .git/HEAD or using sed(1)
 |> on the output of `branch' to find the right name?
 |
 |Have you tried "git symbolic-ref HEAD"?

Not until now.

 |$ git symbolic-ref HEAD
 |refs/heads/master

Works.

 |If you don't want the fully-qualified ref, you can add --short:
 |
 |$ git symbolic-ref --short HEAD
 |master

Yep, works even better.  Fantastic.  Thank you.  And that command
was already existing when i have learned to use git(1), it is even
in the progit-09.markdown as of 2011-09-22 that i have laying
around.  Five years, and anything forgotten.  That is what you get
from working with blinkers on.  Shame!

Thank you Bryan.

--steffen

Re: v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Jakub Narębski]

W dniu 20.09.2016 o 20:54, Bryan Turner pisze:
> On Tue, Sep 20, 2016 at 9:23 AM, Steffen Nurpmeso <steffen@sdaoden.eu> wrote:
>> Hello again,
>>
>> yah, sorry, i'm back again..
>> I try to find a way to find the name of the current branch in an
>> automated way, because i need to ensure that a commit happens on
>> it and no other branch.  Now the problem arises that the commit
>> ref at the time of that commit maybe shared in between several
>> different branches, but no more thereafter, of course:
>>
>>   ?0[steffen@wales ]$ git branch|grep '^*'
>>   * stable/v14.9

Not good, 'git branch' is a porcelain (user facing) command, so it
output may change; e.g. '*' could be replaced with '•'. For example
output for detached HEAD had changed!

>>   ?0[steffen@wales ]$ git name-rev --name-only HEAD
>>   stable/v14.8
>>
>> Is there another way except looking into .git/HEAD or using sed(1)
>> on the output of `branch' to find the right name?
> 
> Have you tried "git symbolic-ref HEAD"?
> 
> $ git symbolic-ref HEAD
> refs/heads/master
> 
> If you don't want the fully-qualified ref, you can add --short:
> 
> $ git symbolic-ref --short HEAD
> master

This does not work for detached HEAD, but perhaps you don't need
to worry about this.

  $ git rev-parse --symbolic-full-name HEAD
  refs/heads/master

But

  $ git checkout HEAD^0
  Note: checking out 'HEAD^0'.

  You are in 'detached HEAD' state. [...]
 
  $ git rev-parse --symbolic-full-name HEAD
  HEAD

  $ git symbolic-ref HEAD
  fatal: ref HEAD is not a symbolic ref

  $ git branch
  * (HEAD detached at 3e2ebf9)
    master

-- 
Jakub Narębski

Re: v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Steffen Nurpmeso]

Hello.

Jakub Narębski <jnareb@gmail.com> wrote:
 |W dniu 20.09.2016 o 20:54, Bryan Turner pisze:
 |> On Tue, Sep 20, 2016 at 9:23 AM, Steffen Nurpmeso <steffen@sdaoden.eu> \
 |> wrote:
 |>> Hello again,
 |>>
 |>> yah, sorry, i'm back again..
 |>> I try to find a way to find the name of the current branch in an
 |>> automated way, because i need to ensure that a commit happens on
 |>> it and no other branch.  Now the problem arises that the commit
 |>> ref at the time of that commit maybe shared in between several
 |>> different branches, but no more thereafter, of course:
 |>>
 |>>   ?0[steffen@wales ]$ git branch|grep '^*'
 |>>   * stable/v14.9
 |
 |Not good, 'git branch' is a porcelain (user facing) command, so it
 |output may change; e.g. '*' could be replaced with '•'. For example
 |output for detached HEAD had changed!

Ok.  I went the road Bryan suggested, i had only forgotten this.
Yes, it caused mysterious bugs once rev-parse reversed the output,
but i didn't understand the order at first, anyway.  With todays'
ever-rotating distributions i don't even try to keep up; currently
unthinkable to use the same release of an OS for five years, like
FreeBSD 5.3.  Well.

  ...
 |>> Is there another way except looking into .git/HEAD or using sed(1)
 |>> on the output of `branch' to find the right name?
 |> 
 |> Have you tried "git symbolic-ref HEAD"?
  ...
 |This does not work for detached HEAD, but perhaps you don't need
 |to worry about this.

No, not for me: it will only switch in between two different
stable/ which exist.  But thanks, just give it to me!

 |  $ git rev-parse --symbolic-full-name HEAD
 |  refs/heads/master

This is a really good suggestion, which i will remember.  I didn't
know this at all yet:

  $ git rev-parse --symbolic-full-name --abbrev-ref=strict HEAD

Seems to do exactly what i want, non-fragile, then.

 ...
 |But
 ...
 |  You are in 'detached HEAD' state. [...]
 | 
 |  $ git rev-parse --symbolic-full-name HEAD
 |  HEAD
 |
 |  $ git symbolic-ref HEAD
 |  fatal: ref HEAD is not a symbolic ref
 |
 |  $ git branch
 |  * (HEAD detached at 3e2ebf9)
 |    master

And name-rev gives "HEAD master~2" in a test of mine, or only
"master~2", or "undefined" if i use --tags, for completeness sake.

Thanks, Jakub.  I'm using the plumbing.

--steffen

Re: v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Junio C Hamano]

Jakub Narębski <jnareb@gmail.com> writes:

>> Have you tried "git symbolic-ref HEAD"?
>> 
>> $ git symbolic-ref HEAD
>> refs/heads/master
>> 
>> If you don't want the fully-qualified ref, you can add --short:
>> 
>> $ git symbolic-ref --short HEAD
>> master
>
> This does not work for detached HEAD, but perhaps you don't need
> to worry about this.

I am not sure what you mean by "does not work".  Asking what ref
HEAD points at to symbolic-ref will tell you it does not point at
anything by exiting with non-zero status and that can be relied
upon.

Asking "symbolic-ref HEAD" has been the way how "git branch" and
other commands find out what branch is currently checked out for
almost eternity ("git symbolic-ref" appeared in Git v0.99.8).

Re: v2.9.3 and v2.10.0: `name-ref' HEAD gives wrong branch name

[Jakub Narębski]

W dniu 21.09.2016 o 18:37, Junio C Hamano pisze:
> Jakub Narębski <jnareb@gmail.com> writes:
>>> Have you tried "git symbolic-ref HEAD"?
>>>
>>> $ git symbolic-ref HEAD
>>> refs/heads/master
>>>
>>> If you don't want the fully-qualified ref, you can add --short:
>>>
>>> $ git symbolic-ref --short HEAD
>>> master
>>
>> This does not work for detached HEAD, but perhaps you don't need
>> to worry about this.
> 
> I am not sure what you mean by "does not work".  Asking what ref
> HEAD points at to symbolic-ref will tell you it does not point at
> anything by exiting with non-zero status and that can be relied
> upon.
> 
> Asking "symbolic-ref HEAD" has been the way how "git branch" and
> other commands find out what branch is currently checked out for
> almost eternity ("git symbolic-ref" appeared in Git v0.99.8).

I'm sorry, I was wrong saying "does not work".  The problem is not
that it does not work, but that you need to take care of exit 
condition to correctly support detached HEAD state, and not end
with empty name for a branch, for example...

But if handled correctly, git-symbolic-ref is as good as git-rev-parse
as a plumbing to resolve current branch name.

Best,
-- 
Jakub Narębski