Thomas Glanzmann <thomas@xxxxxxxxxxxx> wrote:
> so this output is useless if you don't have tagged the commit which
> isn't the case. But thanks for the awareness.
Thanks for not quoting Brian's reply. Because I had to go and
quote it manually, so I can say its *NOT* useless...
> Brian Gernhardt <benji@xxxxxxxxxxxxxxxxxx> wrote:
> > For version information it is far more useful to use --tags or no
> > options (annotated tags only) instead of --all.
> >
> > # On git.git's master this morning:
> > $ git describe HEAD
> > v1.5.2
Here whatever HEAD's commit is is exactly the commit that the tag
v1.5.2 points at. This commit is definately v1.5.2.
> > $ git describe HEAD^^
> > v1.5.2-rc3-97-g03f6db0
Here whatever commit is 2 commits earlier than HEAD is 97 commits
*after* v1.5.2-rc3 was tagged. That's a good deal of information
right there. I know its v1.5.2-rc3 plus a bunch of additional
commits (97 to be exact). Add another commit and that 97 will
go to 98. Wow, look, an automatic version counter! No user
intervention required!
Sometimes I don't even bother tagging git-gui fixes, for exactly
that reason. The output of git-describe is giving me a count along
my maint branch, or my master branch.
Now that g03f6db0 suffix is also very useful, it means its the
commit whose SHA- starts with 03f6db0. That abbreviated SHA-1
is unique at the time that git-describe ran. At 8 hex digits it
will probably also stay unique for quite some time, even in large
projects like the kernel.
And even if that isn't unique later on, I doubt there will be another
commit with the same leading hex digits that is also 97 commits
after v1.5.2, as counted by `git-rev-list v1.5.2..$it | wc -l`.
So even in the case of a later duplicate, we can get back a full
SHA-1.
And did you know that Git knows how to parse those, and can checkout
that commit?
$ git checkout v1.5.2-rc3-97-g03f6db0
Note: moving to "v1.5.2-rc3-97-g03f6db0" which isn't a local branch
If you want to create a new branch from this checkout, you may do so
(now or later) by using -b with the checkout command again. Example:
git checkout -b <new_branch_name>
HEAD is now at 03f6db0... Merge branch 'maint' to synchronize with 1.5.1.6
Wow. Magic! Not useless!
--
Shawn.
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