howto

Links
Tags and remotes
Delete merged branches
SHAs for refs
Finding all branches / tags that contain a specific commit (by message)
Create an annotated tag
Commit pointed to by an annotated tag

Links

git: how to insert a commit as the first, shifting all the others?
Finding a branch point with git
- That specific comment points out the only solution that sort of works.
Sparse checkout
Git tips from the trenches
misc: show-ref, for-each-ref, describe
- git log --graph --decorate --oneline
- git name-rev

Pickaxe searches

Checking out a specific revision to a different filename.

See stackoverflow.com: git-checkout older revision of a file under a new name

git show HEAD^:dir1/dir2/dir3/main.cpp > old_main.cpp

Patching

git apply =(git format-patch -k --stdout 'commit_A..commit_B')

Where

Flag	Description
`-k, --keep-subject`	Do not strip/add [PATCH] from the first line of the commit log message.
`--stdout`	Print all commits to the standard output in mbox format, instead of creating a file for each one.

Splitting Commits

See splitting commits

Resolving a merge conflict

Like p4 nothave

# Don't ignore files in .gitignore/excludesfile, etc.
git ls-files . --others

# DO ignore files in .gitignore/excludesfile, etc.
git ls-files . --others --exclude-standard

Any diffs around?

# Have return code state if there are any diffs
git diff --no-ext-diff --quiet
git diff --no-ext-diff --quiet --cached

Keep some untracked changes around without committing

Use git update-index --assume-unchanged

It has some caveats.

--assume-unchanged, --no-assume-unchanged
- When these flags are specified, the object names recorded for the paths are not updated. Instead, these options set and unset the "assume unchanged" bit for the paths. When the "assume unchanged" bit is on, git stops checking the working tree files for possible modifications, so you need to manually unset the bit to tell git when you change the working tree file.
- This option can be also used as a coarse file-level mechanism to ignore uncommitted changes in tracked files. Git will fail (gracefully) in case it needs to modify this file in the index e.g. when merging in a commit; thus, in case the assumed-untracked file is changed upstream, you will need to handle the situation manually.

What is the current branch?

Ref
- Git Blame: Checking the current branch programatically
- SO: How to programmatically determine the current checked out Git branch

Shell code:

# From: http://git-blame.blogspot.com/2013/06/checking-current-branch-programatically.html
if branch=$(git symbolic-ref --short -q HEAD); then
  echo on branch $branch
else
  echo not on any branch  # detached head.
fi

# Misc/related commands.
git symbolic-ref --short -q HEAD  # What happens when head is detached?

# rev-parse handles packed refs.
git rev-parse --symbolic-full-name --abbrev-ref HEAD
git rev-parse --symbolic-full-name --abbrev-ref '@{u}'         # get remote tracking branch
git rev-parse --symbolic-full-name --abbrev-ref '@{upstream}'  # get remote tracking branch

Tags and remotes

Ref: http://stackoverflow.com/a/5496610

[remote "upstream"]
    url = …
    fetch = +refs/heads/*:refs/remotes/upstream/*
    # Ref: http://stackoverflow.com/a/5496610
    tagopt = --no-tags
    fetch = +refs/tags/*:refs/tags/upstream/*

Delete merged branches

git branch --merged | xargs git branch -d

SHAs for refs

# These two are equivalent
git for-each-ref --format '%(objectname)' -- 'refs/remotes/chirayu/presubmit*'
git rev-parse --glob='refs/remotes/chirayu/presubmit*'

# HEAD is special and not a "ref", so you would need to
# use git rev-parse for it
git rev-parse --verify HEAD

Finding all branches / tags that contain a specific commit (by message)

COMMIT_MSG_GREP='fixed foo'
for ref in $(git show-ref | awk '{ print $1 }') ; do
  for sha in $(git log --all --grep=$COMMIT_MSG_GREP) ; do
    if git merge-base --is-ancestor $sha $ref ; then
      print -r -- $ref
    fi
  done
done

Create an annotated tag

git tag -a -f -m 'PendingAsync service / whenStable / PR 1489: version using Future/Completer' pr_1489_pending_async_with_futures

Commit pointed to by an annotated tag

#  <rev>^{}, e.g. v0.99.8^{}
#      A suffix ^ followed by an empty brace pair means the object
#      could be a tag, and dereference the tag recursively until a
#      non-tag object is found.
git rev-parse 'v0.12.0^{}'

# show-ref --dereference
#   -d, --dereference
#       Dereference tags into object IDs as well. They will be shown
#       with "^{}" appended.
git show-ref --dereference  v0.12.0
# 299ed9bb2ce71378b4f29dd10d3b6c93ebb0371f refs/tags/angular/v0.12.0
# 65037f85dbd49d56bb4852be355bb1b9c3a3390d refs/tags/angular/v0.12.0^{}
# 299ed9bb2ce71378b4f29dd10d3b6c93ebb0371f refs/tags/v0.12.0
# 65037f85dbd49d56bb4852be355bb1b9c3a3390d refs/tags/v0.12.0^{}