Allison Kaptur

An occasional blog on programming

New Git Tricks

I picked up a couple of new tricks at Hacker School’s intermediate/advanced Git seminar, led by Peter Bell.

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$ git checkout -

This checks out whatever you had checked out last. Thanks, Nina!

Draw a graph of the commit history:

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git-advanced [master]\ $ git log --graph --oneline --all
*   b2da179 Merge branch 'test-graph'
|\  
| * d71e4fc testing graph thing
* | 8535311 still testing graph
|/  
* b90b105 Added contact form
* b36ba51 added gitignore to ignore generated log files
* 70461dc added about
* c57f995 added homepage

You can alias this with git config --global alias.plog "log --graph --oneline --all". (Looking at this graph may motivate you to start using git merge --no-ff.) You can substitute whatever you want for plog above.

If you get really screwed up, it’s reflog time! (This is pronounced ref-log, not re-flog as I’d been reading it. On the other hand, as my colleague Alan notes, “You damn well ought to feel penitent if you’re wedged enough to need the reflog.”) Here, we’re using git reset to undo the last commit. Even though the commit doesn’t appear in git log anymore, there’s still a references to it in the reflog.

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git-advanced [master %]\ $ git add tester.css
git-advanced [master +]\ $ git commit -m "add some file"
git-advanced [master]\ $ git reset HEAD~1
git-advanced [master %]\ $ git add tester.css
git-advanced [master +]\ $ git commit -m "redoing some file"

git-advanced [master]\ $ git log --oneline
8039ec5 redoing some file
b2da179 Merge branch 'test-graph'
8535311 still testing graph
d71e4fc testing graph thing

git-advanced [master]\ $ git reflog
8039ec5 HEAD@{0}: commit: redoing some file
b2da179 HEAD@{1}: reset: moving to HEAD~1
848874d HEAD@{2}: commit: add some file

It turns out that there is a better way to get a commit sha than running git log and copying and pasting the relevant shas. You can use rev-parse instead.

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git-advanced [master]\ $ git rev-parse HEAD~2
0fafe464f4b7d524c8ba707ea2115950d6dd4bdf
git-advanced [master]\ $ git rev-parse master
8039ec584485540f07aac1209389022f627bc8c5

Then you can inline with backticks!

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git-advanced [master]\ $ git diff `git rev-parse HEAD~2` `git rev-parse HEAD`

Now go forth and git in peace.