git notes main page | gitolite main page | license

IMPORTANT NOTE: although this page has a "gitolite.com" URL, this is not about gitolite. That's just an artifact of "sitaramc.github.com" being translated to "gitolite.com" and so ALL my git related stuff gets carried over. Gitolite documentation has another /gitolite in the URL, so you can tell. My apologies for this confusion.

backing up work in progress

This is how you can backup everything on your local repo that is not already on one of your remotes, including all untracked files not covered by the ignore mechanism. I use a script based on this to save my work to a remote server at regular intervals, in case of a disaster (hardware failure, etc) on the regular desktop.

# sort of like stash; untracked files also saved
git commit --allow-empty -m wip-index-state
git add -A && git commit --allow-empty -m wip-worktree-state

# make a temp branch (FIXME: should we do this first?)
git branch wip-backup ||
    die 'could not create wip-backup branch; aborting';

# unstash
git reset --mixed HEAD^
git reset --soft HEAD^

# create the bundle and remove the temp branch
git bundle create /tmp/sos.bdl --all --not --remotes
git branch -D wip-backup

# copy that file wherever you want, however you want...
rsync /tmp/sos.bdl bkphost:   # or scp, or whatever

conflicts on pull/merge

• try gitk --merge conflicted_path

• git diff MERGE_HEAD...HEAD (note the three dots) shows you differences between the common ancestor and your HEAD.

• similarly git diff HEAD...MERGE_HEAD shows you differences between the common ancestor and the branch you’re trying to merge

• git checkout --conflict=diff3 conflicted_path is a novel way of getting all 3 versions into the file so you can hack at it in vim

• you can tell git blame to only show important changes, like so (pity it does not work with the GUI blame)

  git blame -C $(git merge-base HEAD MERGE_HEAD).. conflicted_path

log pickaxe and blame

• finding out when a particular change happened or who made it

  git log -S"some code line" file.c   # why is this called pickaxe search?
  git blame -b file.c

what are all these “HEAD”s?

• ORIG_HEAD: pull or merge (or anything that moves HEAD drastically) leave a copy of the old head with this name. Reset can use it if needed. (see man git-reset). reset itself copies the old HEAD to ORIG_HEAD, though that seems less useful
• FETCH_HEAD: records the branch you fetched from a remote repository with your last ‘git-fetch’ invocation
• MERGE_HEAD records the commit(s) you are merging into your branch when you run ‘git-merge’

garbage collection

NOTE: this section is old; I have not looked at it with respect to recent git versions.

• Warning: git gc --prune is dangerous if others may be pushing to the repo at the same time!

• Warning: git gc may increase the space used, since it even unpacks objects that were in packs if they became unreachable. This is the same thing as git repack -Adf (note the uppercase “A”)

• To bring the repo size down the bare minimum, you need both the following commands (neither command by itself does the whole job). Also Note the lowercase “a” on the “repack”, which says you want to blindly discard unreachable objects instead of keeping them as loose objects.

  git repack -adf     # kills in-pack garbage
  git prune           # kills loose garbage

• (from the do-you-really-want-to-do-this? department)

  git reflog expire --expire=10days --all
  # use expire-unreachable to limit it a bit
  # use branchname(s) instead of --all
  # units can be seconds, minutes, etc

recovering a dropped stash:

the GUI way

You dropped a stash that was created recently, and now you want to recover it. As long as you did not do a garbage collection in between, this should work:

gitk $(git fsck | grep commit | cut -f3 -d' ') --since='1 week ago'

The part within the parenthesis finds all unreachable commit objects and returns their hashes. If you never did a garbage collect there might be too many false positives so the --since clause (which you can adjust to whatever you want of course; mine is just an example) limits the display to commits created recently.

A “stash” has a very recognisable, triangular, shape in the commit DAG, and with gitk you can visually find stashes really fast. For me, this is the kind of task that calls out for a GUI – infrequently required, no conceivable need to automate, and containing data that stands out visually.

the command line way

Writing something longer than that for a problem that occurs once in a blue moon is not my style (very low ROI!), but doener gave me this:

git fsck --unreachable | grep commit | cut -d\  -f3 |
xargs git log --no-walk --merges --grep='^\(WIP on \|On \)\((no branch)\|[^ ]\+\):'

I knew about --merges but not --no-walk, and I anticipate using it a lot more in future :-)