Git

Signing work

Get your GPG configured, and a personal key installed. Configure Git to use your personal key.

$ git config --global user.signingkey 0A46826A

Signing commits

You can sign commits simply by adding -S once your environment is configured.

$ git commit -S -m 'push a signed commit'

You can check and verify via git log:

$ git log --show-signature -1

You can configure git log to check any signatures and list them in output via %G? format.

$ git log --pretty="format:%h %G? %aN  %s"

You can also reject commits that are unsigned and invalid:

$ git merge --verify-signature non-verify

$ git merge --verify-signatures signed-branch

Sign the merge commit itself:

$ git merge --verify-signatures -S signed-branch

Workflows

Making a pull request

1. Fork the project

2. Clone your fork

$ git clone git@gitrepo.com:mhan/forkedproject.git

3. Set up environment to keep fork updated

Set up upstream remote:

$ git remote add upstream git@gitrepo.com:unmit/project.git

Update your fork:

$ git fetch upstream
$ git branch -va
$ git checkout master
$ git merge upstream/master

4. Make updates of your own

Create a new branch before making any changes

$ git checkout master
$ git branch newfeature
$ git checkout newfeature

5. Submit a pull request

Rebase your development branch against upstream master branch.

$ git fetch upstream
$ git checkout master
$ git merge upstream/master
$ git checkout newfeature
$ git rebase master

Squash multiple commits into fewer commits

$ git checkout
$ git rebase -i master

Submit

• After pushing to the forked project, select development branch and click the pull request button.

Commands

Add

Add only modified and deleted files:

$ git add -u

Tags

Signing tags:

$ git tag -s v2.17 -m 'version 2.17 signed by MH'
$ git show v2.17

With the signer's public key in the keyring, you can verify the tag:

$ git tag -v v2.17

Upload a specific tag:

$ git push origin v2.29.1

Upload all tags:

$ git push origin --tags

Remove a tag locally

$ git tag -d <tagname>

Remove a tag on the remote repo

$ git push --delete origin v0.1.8

Get the latest tag in the current branch

$ git describe --abbrev=0 --tags

• Reference: Tag-related commands

Clone a specific branch

$ git clone --depth 1 --single-branch -b 2.0.0 https://github.com/user/reponame.git

Get a build number

A commit count can be used as a build number for a revision (e.g. HEAD, master, a commit hash):

$ git rev-list --count <revision>

To get the commit count across all branches:

$ git rev-list --all --count

To get the number of commits without merges for develop branch:

$ git rev-list --no-merges --count develop

Add a local branch that tracks a remote branch

$ git branch --track greet origin/greet
$ git branch -a
$ git merge origin/master

Pulling changes from a remote

$ git fetch
$ git merge origin/master

is equivalent to:

$ git pull

Cleaning up remote branch list

This cleans up and removes any branches that are no longer on the remote

$ git remote prune origin

Rebase a branch

$ git checkout cbranch
Switched to branch 'cbranch'

$ git rebase master
First, rewinding head to replay your work on top of it...
Applying: added Greeter class
Applying: hello uses Greeter
Applying: updated Rakefile

$

Start a new branch

$ git checkout -b newbranch
Switched to a new branch 'newbranch'

Merge a branch

$ git checkout autonotif
Switched to branch 'autonotif'

$ git merge <branchname>
Merge made by the 'recursive' strategy.
 foobarrecords_savenew.hns | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 foobarrecords_savenew.hns

Merges <branchname> onto autonotif branch

Rename a branch

and update in the remote as well

$ git checkout <old_name>

$ git branch -m <new_name>

$ git push origin --delete <old_name>

$ git push origin -u <new_name>

Delete a branch

• Delete a local branch

$ git branch -d hotpatch1

• Delete a remote branch

git push origin --delete hotpatch1

• Delete a remote branch that as no actual reference on the remote

git branch -r -d origin/hotpatch1

List merged branches

List branches merged into master

$ git branch --merged master

List branches merged into HEAD (i.e. tip of current branch)

$ git branch --merged

List branches that have not been merged

$ git branch --no-merged

Undo last commit

This undo is recorded as a part of the git log.

$ git revert HEAD

Fix or amend last commit

$ git commit --amend

Undo changes to a file

$ git checkout -- filename

Reset the branch to a specific point in the past

$ git reset --hard <hash>

--hard parameter also updates the working directory. Reset shouldn't be used in a group project on a remote repository because of its potential for confusion.

Reset the branch to a specific branch on a remote

$ git reset --hard origin/master

Ignore files

Temporary ignore changes to a file

$ git update-index --assume-unchanged <filename>

Back to tracking changes to the file

$ git update-index --no-assume-unchanged <filename>

Get a list of folders and files that are assume-unchanged

$ git ls-files -v | grep '^h'

Ignore file modes

This is useful when working with multiple file systems.

$ git config core.filemode false

Maintenance command

Verify the connectivity and validity of the objects

$ git fsck --unreachable

Manage reflog information

$ git reflog expire --expire=0 --all

Pack unpacked objects in a repository

$ git repack -a -d -l

Prune all unreachable objects from the object database

$ git prune

Clean up unnecessary files and optimize the local repository

$ git gc --aggressive

Useful git aliases

This is a snapshot of my ~/.gitconfig

[user]
        name = Michael Han
        email = mhan@pfg.fjfj.com
[core]
        editor = vim
        autocrlf = input
        safecrlf = true
[color]
        ui = always
[alias]
        co = checkout
        ci = commit
        st = status
        br = branch
        df = difftool
        hist = log --pretty=tformat:\"%C(yellow)%h %C(green)%ad %Creset| %s%C(red)%d %C(bold blue)[%an]\" --graph --date=short
	hist2 = log --graph --abbrev-commit --decorate --date=relative --format=tformat:'%C(bold blue)%h%C(reset) - %C(bold green)(%ar)%C(reset) %C(white)%s%C(reset) %C(dim white)- %an%C(reset)%C(bold blue)\" --graph --date=short
        histall = log --pretty=tformat:\"%C(yellow)%h %C(green)%ad %Creset| %s%C(red)%d %C(blue)[%an]\" --graph --date=short --all
        hist10 = !git log --pretty=tformat:\"%C(yellow)%h %C(green)%ad %Creset| %s%C(red)%d %C(blue)[%an]\" --graph --date=short | head -n 10
        hist10all = !git log --pretty=tformat:\"%C(yellow)%h %C(green)%ad %Creset| %s%C(red)%d %C(blue)[%an]\" --graph --date=short --all | head -n 10
        listnames = diff-tree --no-commit-id --name-status -r
        type = cat-file -t
        dump = cat-file -p
        ignore = update-index --assume-unchanged
        track = update-index --no-assume-unchanged
        ignorelist = !git ls-files -v | grep -s ^'h ' | cut -b 1-2 --complement[diff]
        tool = vimdiff
[difftool]
        prompt = false
[merge]
        defaultToUpstream = true

Quick Start Guide

• Using Git for collaborating on text-based data files

Links

http://qugstart.com/blog/ruby-and-rails/create-a-new-git-remote-repository-from-some-local-files-or-local-git-repository/

http://gitimmersion.com/

http://kris.me.uk/2010/09/30/git-repository-server-gitolite.html

http://www.lucidlynx.com/how-to-install-gitweb-in-ubuntu/

http://mustalikachwala.blogspot.com/2012/07/ubuntu-1204-installing-gitolite-and.html

http://ben.kulbertis.org/2011/10/synchronizing-a-mysql-database-with-git-and-git-hooks/

http://viget.com/extend/backup-your-database-in-git

http://longair.net/blog/2009/04/16/git-fetch-and-merge/

a warning against pull

'http://git-scm.com/book/en/Git-Branching-Basic-Branching-and-Merging

Clients

• Sapling
  • Meta engineering blog entry (2022-11)