Git cheatsheet

Commits

Lists and Graphs

List just the hash and the commit message for the ten most recent commits:

git log --pretty=oneline -n 10

Show a nice graph:

git log --oneline --graph --decorate

Display and listing files

Display list of files in a commit

Last commit:

git show --pretty="format:" --name-only

Commit before that:

git show --pretty="format:" --name-only HEAD~1

Display file contents for a given revision

git show ee63c9b61122bfe7e24f8512a3359157ae10066b:components/customer_info

Display file contents for in a branch

git show master:components/customer_info

Log commits for a file that was moved or removed

git log -- components/customer_info

List untracked files

git ls-files --others --exclude-standard

List files deleted in the working directory

git ls-files -d

To restore them:

git checkout `git ls-files -d`

Display list of files with the last commit date

racke@ambas:$ for file in $(find lib/ -type f ); \
  do DT=$(git log -n 1 --pretty=%ci -- $file;); echo "$file:$DT "; done
lib/PerlDance.pm:2016-09-05 15:58:07 +0200
lib/PerlDance/Routes.pm:2016-08-08 14:42:54 +0200
lib/PerlDance/Filter/Wiki.pm:2015-09-15 14:39:36 +0200
lib/PerlDance/Filter/MongerGroups.pm:2016-08-19 11:09:05 +0200
lib/PerlDance/Filter/Markdown.pm:2015-08-06 15:53:25 +0200

Merges

Prevent dirty merges

$ git config --global pull.ff only
$ git pull
fatal: Not possible to fast-forward, aborting.
$ git pull --rebase
Successfully rebased and updated refs/heads/topic/clean-123

Show all commits in a merge

Given that the hashref of the merge is 6d31d51, you can use the following command to show all commits in that merge:

git log 6d31d51^..6d31d51

Store empty directory in the Git repository

In case you want to keep a directory for dynamic content in the Git repository, but no files in it, use the following .gitignore file:

# Explanation about the purpose of the directory
*
!.gitignore

Removing and purging files

Remove dynamic files

Sometimes you accidentally add dynamically created files to the Git repository. In this case, you usually want to remove the file from the repository but not from the working directory.

You can do this as follows, e.g for the file adjtime:

git rm --cached adjtime
echo adjtime >> .gitignore
git add .gitignore
git commit -m "Remove dynamically generated file"

Purge untracked files

Please doublecheck first that you don't remove files with valuable content.

Purge untracked files:

git clean -f ...

Purge untracked files including directories:

git clean -df sql/

Reverting commits

Reverting multiple commits

If the commits are consecutive, you can do:

git revert  4ea5493d9ac1d6ebcdb0bd29d70275e82ef23467^..d56fe7e13df7ec26c73d744077d7b079b70cc029

Where 4ea5493 is the oldest and d56fe7e is the newest commit to revert.

Please note that Git will still create one revert commit for each of the commits to be reverted.

Get rid of Git commits

Remove the last three commits (~3):

git reset --hard HEAD~3

Please note that you will loose uncommitted work as well.

"Root" commits

The following command shows you all parentless (root) commits accessible from current branch, useful to find the initial commit in the repository:

git rev-list --max-parents=0 HEAD

It is useful to create an empty commit as "root" commit as the "root" commit cannot be rebased:

$ git commit --allow-empty -m "Initial commit."
[master (root-commit) 99dbf81] Initial commit.

Signing commits/tags

Force signing

git config --global commit.gpgsign true

Multiple keys

If you have multiple keys with the same email address, you can configure the correct one as follows:

git config --global user.signingkey FA2720F8

Signing on remote hosts

Add extra socket to your GPG agent configuration file (~/.gnupg/gpg-agent.conf):

extra-socket /path/to/extra-socket

Stage

Stage changes for the next commit:

git add README.md

Display staged files:

git diff --name-only --cached

Unstage changes:

git reset HEAD

Tags

Show all tags and corresponding messages

git tag -l '*' -n 1

Display a tag

$ git show 6.2.70
tag 6.2.70
Tagger: Stefan Hornburg (Racke) <racke@linuxia.de>
Date:   Thu Nov 10 12:41:43 2022 +0100

[-release]Preparing version 6.2.70
-----BEGIN PGP SIGNATURE-----
...

Add a signed tag

git tag -a -s -m "Release 0.21" v0.21

Push tags to remote repository

Tags are not automatically pushed with git push:

git push --tags

Diffs & Logs

Show all files changed in a branch

$ git checkout mybranch
$ git diff --name-only master
...

Compare releases

git diff 2.0.0 2.0.3

The diff can be restricted to changes in a file or a directory:

git diff 2.0.0:tasks 2.0.3:tasks

Commits

Diff for the last three commits:

git diff HEAD~3 HEAD

Ignore whitespace

Options for a diff ignoring whitespaces:

--ignore-space-at-eol

Changes at end of line (e.g. LF to CRLF)

-b

As above plus collapses multi whitespaces into one

-w

Ignores all whitespace changes (usually not what you want ...)

Reverse diff

git diff -R

This can be useful, e.g to display deleted whitespace.

Formatting

Show the short hash:

git log --abbrev-commit

Remotes

Display remotes

Short form (just the names):

~# git remote
origin
upstream

Long form (includes URL):

~# git remote -v
origin    git@github.com:racke/dancer2.git (fetch)
origin    git@github.com:racke/dancer2.git (push)
upstream    git@github.com:PerlDancer/Dancer2.git (fetch)
upstream    git@github.com:PerlDancer/Dancer2.git (push)

Add remote repository

~# git remote add origin git@github.com:racke/dancer2.git

Rename remote repository

~# git remote rename origin upstream

Change URL for remote repository

~# git remote set-url upstream git@github.com:racke/dancer2.git

Reset after remote rebase

~# git reset --hard origin/topic/returns-user-control-3964

Please note that you will loose uncommitted changes.

Checkout

Checkout a new branch from a tag

Creates a new branch topic/v2.1-fixes from tag v2.1 and switches to it:

$ git checkout -b topic/v2.1-fixes v2.1
Switched to a new branch 'topic/v2.1-fixes'

Stash

Add to stash

With message:

$ git stash save "Old cruft."

List stash entries

$ git stash list

Show list with creation date of the entries:

$ git stash list --date=local

Show stash contents

$ git stash show -p stash@{1}

Include untracked files

git stash -u

git stash save -u "Stash away experiments"

Stash specific file(s)

git stash push default/web_tt2/subscriber_table.tt2

Stash a directory including untracked files:

git stash push -u roles/sympa

Retrieve stash

$ git stash pop stash@{1}
On branch topic/header/from-as-envelope-sender
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   src/lib/Sympa/Spindle/ToList.pm

no changes added to commit (use "git add" and/or "git commit -a")
Dropped stash@{1} (9579fe0d020a8e63733dff961fc3bd0865100959)

Pick a file from the stash

git checkout stash@{0} -- src/lib/Sympa/Bulk.pm

Branches

Tracking branches (set upstream)

Track remote branch pr-fix-typo:

git branch -u origin/pr-fix-typo

This effectively sets the upstream for the current branch to origin/pr-fix-typo.

Compare files between branches

git diff master:README pr/fix-typo:README

This also works for directories.

Files added in a branch

This lists all files added in the branch topic/transaction-status and not present in the master branch.

git diff --name-only --diff-filter=A master topic/transaction-status

Similar for modified files only:

git diff --name-only --diff-filter=M master topic/transaction-status

Find branch for a commit

Local repository:

$ git branch --contains c0cc8e3e185e1de308b0c86b01f8fccc98dd4485
  topic/imap-search-header-2020-03-12

Remote repositories:

$ git branch -r --contains c0cc8e3e185e1de308b0c86b01f8fccc98dd4485
  github/topic/imap-search-header-2020-03-12
  origin/topic/imap-search-header-2020-03-12

First commit for a branch

Show starting point of the branch in relationship to the main branch.

git log --reverse main..topic/pr-foo-bar

Show commits in a branch not merged into master

git cherry -v master feature/mobile

You can also compare to a remote branch:

git cherry -v master origin/feature/mobile

If there are no unmerged commits left, you can delete the local and remote branch with the following commands:

git branch -d feature/mobile

git push origin :feature/mobile

Merge base

The merge base is the common commit where the current branch diverged from. You can determine this commit with the merge-base command:

git merge-base master topic/org-addons

It is quite a common case to only see the logs or the diff of the changes in your current branch since they diverged.

But the following command will also consider the changes in master since the diverge:

git diff master..topic/org-addons

Instead you can use

git diff $(git merge-base master topic/org-addons)..topic/org-addons

or the shorthand (three dots):

git diff master...topic/org-addons

The same applies of course to the log command as well.

Just show the name of the current branch

git symbolic-ref --short HEAD

Rename branch

This renames the current branch. It doesn't affect the remote branch.

git branch -m topic/newname

To rename a branch other than the current one:

git branch -m topic/oldname topic/newname

In order to rename the remote branch we are doing two steps.

First we delete the old remote branch and push the new local branch:

git push origin :topic/oldname topic/newname

Second we update the remote tracking information:

git branch -u origin/topic/newname

Move branch

Move from master to main:

git branch -M main

Merged and unmerged branches

Show merged branches:

git branch --merged

Show remote merged branches:

git branch -r --merged

Show unmerged branches:

git branch --no-merged

Sorted by age

This sorts local branches by date of the latest commit and displays the commit date and the branch name:

for C in $(git for-each-ref --sort=committerdate refs/heads --format='%(refname)');
do
   git show -s --format="%ci $C" "$C";
done

Same for remote branches from origin:

git fetch origin

for C in $(git for-each-ref --sort=committerdate refs/remotes/origin --format='%(refname)');
do
   git show -s --format="%ci $C" "$C";
done

Configuration

Name and email

git config --global user.name "Stefan Hornburg (Racke)"
git config --global user.email "racke@linuxia.de"

Break out part of the repository

One example is to extract common code out of a Perl module to start a separate module, but keep the history on the files involved, e.g. extract code out of Interchange6::Schema into Test::DBIC::Roo.

First step is to clone the repository into a new directory:

git clone git@github.com:interchange/interchange6-schema.git Test-DBIC-Roo
cd Test-DBIC-Roo

Now we decide which files respective directories we are going to remove from the repository:

FILE_LIST=".gitignore .travis.yml bin CHANGES lib/Interchange6/Schema lib/Interchange6/Schema.pm lib/Interchange6/Test/Role/Fixtures.pm Makefile.PL MANIFEST MANIFEST.SKIP README t/inflatecolumn_datetime.t t/lib"

Go through the commit history and check if everything is fine for you. If yes, the next step is to rewrite the history of the repository:

git filter-branch \
--index-filter "git rm -r --cached --ignore-unmatch $FILE_LIST" \
--prune-empty \
HEAD

If yes, clean out Git objects which are no longer relevant to the new repository:

git for-each-ref --format='delete %(refname)' refs/original | git update-ref --stdin
git reflog expire --expire=now --all
git gc --prune=now

Another use case is the removal of a file and its history due to legal or privacy reason.

git filter-branch --tree-filter somefile.txt HEAD

Shell

It is quite helpful to show Git related information in your shell prompt.

If you are using the ~/.bashrc from the /etc/skel directory on Debian your shell prompts are configured as:

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

So a prompt could look like:

racke@linuxia:~/provisioning/ansible$

After we modified the prompts to include the Git branch information, the definitions look like:

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\[\033[01;35m\]$(__git_ps1 " (%s)")\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w$(__git_ps1 " (%s)")\$ '
fi

After reloading your ~/.bashrc the prompt will change to include the Git branch information for a directory (if any):

racke@linuxia:~/provisioning/ansible (master)$

We can also add further information with setting the GIT_PS1_SHOWDIRTYSTATE environment variable.

So if you have changes in this working directory, the prompt shows an asterisk after the branch name:

racke@linuxia:~/provisioning/ansible (master *)$