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Git

Source code mirror: https://github.com/git/git

Ask HN: Apps that are built with Git as the back end? - https://news.ycombinator.com/item?id=33261862

Upstream branch​

Important: 'upstream' is about branches, not repositories - see this.

Documentation of git push -u: https://git-scm.com/docs/git-push#Documentation/git-push.txt--u

git push -u origin main
git push --set-upstream origin main

To avoid having to do this we can set autoSetupRemote to true:

# Set value
git config --global push.autoSetupRemote true
git config --global --add --bool push.autoSetupRemote true

# Get value
git config --global push.autoSetupRemote

See https://twitter.com/JI/status/1546948817462800384 and https://stackoverflow.com/a/72401899/4034572.

Undo last commit​

If not pushed yet

# keep changes
git reset --soft HEAD^

# discard changes - IMPORTANT: THIS ALSO DISCARDS ANYTHING NOT STAGED
git reset --hard HEAD^

source

On a public commit

git revert HEAD

Also see: git undo: We can do better

Merge changes from remote master branch to a feature branch without switching to master​

git checkout some-branch
git fetch origin # gets you up to date with origin by getting all commits on all branches, but named 'origin/branch'
git merge origin/master # brings all commits in 'origin/master' to whatever branch we are; we could use --ff-only
git fetch origin master:master # update master if we have a feature branch checked out
git fetch origin && git merge origin/main && git fetch origin main:main

source-part-1 source-part-2

Revert the changes done on a file (or files) in a branch, so that it's content is the same as develop or master​

git checkout <branch> -- <filename>

Eg: git checkout develop -- buildsystem/versions.gradle

This leaves in the staging area the changes that bring the file to the same contents as develop. You need to commit then.

Note that you can put as many files as you want: git checkout <branch> -- <filename> ... <filename>

source1 source2

View file line history/changes​

Show the changes from line 135 to 140:

git log --pretty=short -u -L 135,140:file/path/something.txt

source

git show​

https://git-scm.com/docs/git-show

git show
git show HEAD~1
git show HEAD@{5} # Use 'git reflog' to see the reflog
git show @~1 # @ is the most recent commit
git show -2 # Last 2 commits, both
git show --summary # Do not show file changes, only header info
git show 2.4.0 # A tag
git show branch:file # Eg 'git show main:README.md'
git show main@{yesterday}

Referencing previous commits​

https://stackoverflow.com/questions/16062358/referring-to-the-previous-next-commit-in-git

https://git-scm.com/book/en/v2/Git-Tools-Revision-Selection

GitHub pull request​

https://gist.github.com/Chaser324/ce0505fbed06b947d962

http://blog.davidecoppola.com/2016/11/howto-contribute-to-open-source-project-on-github/

git remote add upstream git@github.com:Kotlin/kotlinx.coroutines.git

Incorporating upstream changes​

git fetch upstream master
git log --oneline --graph --decorate --all
git checkout master
git merge upstream/master
git push origin master

error: pathspec 'some-remote-branch' did not match any file(s) known to git​

When trying to checkout a remote branch (eg when reviewing a pull request), sometimes we get the error "error: pathspec 'some-remote-branch' did not match any file(s) known to git".

To fix it run git fetch --all.

More info: https://stackoverflow.com/questions/30800454/error-pathspec-test-branch-did-not-match-any-files-known-to-git

Rebase​

Squash, Merge, or Rebase? https://matt-rickard.com/squash-merge-or-rebase

Rebase Considered Harmful: https://www.fossil-scm.org/home/doc/trunk/www/rebaseharm.md - See discussion on HN

Golden Rule of Rebasing​

The golden rule of git rebase is to never use it on public branches.

https://www.atlassian.com/git/tutorials/merging-vs-rebasing#the-golden-rule-of-rebasing

--update-refs​

https://github.blog/2022-10-03-highlights-from-git-2-38/#rebase-dependent-branches-with-update-refs - https://news.ycombinator.com/item?id=33071275

Rebase interactive​

https://git-scm.com/docs/git-rebase

git rebase -i <commit you want to amend>^
# or with the alias
grbi <commit you want to amend>^

r or reword - amend commit message (note that if we are only rewording we don't need to do any of the following commands, just save the new commit message and we are done)

gc! (git commit --amend)
grbc (git rebase --continue)

e or edit - modify commit

// edit file(s)...
gaa (or) ga some/file.txt
gc! (git commit --amend)
# it's also possible to do just do gcan!, or gaa and then gcn!
grbc (git rebase --continue)

Rebase until first (root) commit​

git rebase -i --root

Amend​

https://git-scm.com/docs/git-commit

-a/--all: Automatically stage files that have been modified and deleted, but new files you have not told Git about are not affected

--no-edit: Use the selected commit message without launching an editor. For example, git commit --amend --no-edit amends a commit without changing its commit message.

alias | grep amend:

'gc!'='git commit -v --amend'
'gcn!'='git commit -v --no-edit --amend'

'gca!'='git commit -v -a --amend'
'gcan!'='git commit -v -a --no-edit --amend'

Amend undo​

https://stackoverflow.com/questions/1459150/how-to-undo-git-commit-amend-done-instead-of-git-commit

Fix conflict 'both added'​

https://stackoverflow.com/questions/9823692/resolving-a-both-added-merge-conflict-in-git

Estic a una branca i faig merge de dev a la meva branca. Si vull lo de dev faig:

git checkout --theirs <filename>
git add <filename>

I si vull lo de la meva branca:

git checkout --ours <filename>
git add <filename>

Nota: pel <filename> es pot fer servir * per seleccionar varis fitxers alhora, i també pot ser una carpeta.

Overwrite/reset local branch like remote branch​

git reset --hard @{u}

or

git fetch origin
git reset --hard origin/mybranch

source1, source2

Remove untracked files​

git clean -f -d

Prune​

git remote prune origin

Ensure merge without merge commit with --ff-only​

From the docs:

--ff is the default...

With --ff, when possible resolve the merge as a fast-forward (only update the branch pointer to match the merged branch; do not create a merge commit). When not possible (when the merged-in history is not a descendant of the current history), create a merge commit.

With --ff-only, resolve the merge as a fast-forward when possible. When not possible, refuse to merge and exit with a non-zero status.

git checkout -b feature-branch

# make some commits

git rebase main
git checkout main
git merge --ff-only feature-branch

source

--ff-only docs

See commit and code differences between two branches​

# commits
git log main..feature-branch
# code
git diff main..feature-branch
# files changed
git diff --name-status main..feature-branch

Note that you can have 3 dots (...). And if you've already switched to feature-branch you can use git log main...

See source

Squash all commits on a branch​

Can be used to split a big pull request into various PR by creating several commits.

git checkout your-branch
git reset $(git merge-base master-or-develop your-branch-name)

This leaves all changes on the branch at the staging area. Then you can git add . and git commit.

source

Stash​

https://git-scm.com/docs/git-stash

Stash with message​

git stash push -m "Some message"

Stash only staged changes​

https://git-scm.com/docs/git-stash#Documentation/git-stash.txt---staged

git stash push --staged
git stash push -S
git stash save --staged
git stash save -S

Tags​

View: git show 2.4.0

Delete local tag: git tag -d 2.4.0

Delete remote tag: git push -d origin 2.4.0

Push all tags: git push -–tags or git push origin --tags

Always use annotated tags​

git tag -a v1.0

They have extra information like author, date, SHA and message (more info).

Search string on git history​

git log -S something
git log -p -S something

source

Remove carriage return​

If you see ^M run sed -i.bak $'s/\r//' filename (with backup) or sed -i '' -e $'s/\r//' filename (no backup).

source

Branch name​

Set the default branch name for new repositories​

git config --global init.defaultBranch <name>

Rename local branch only​

git branch (-m | -M) [<oldbranch>] <newbranch>

Eg to rename master to main:

  • If you are in master: git branch -m main.
  • If you are not in master git branch -m master main.

Rename local and remote branch​

# Rename:
git branch -m new-name # if we are on the branch
git branch -m old-name new-name # if we are not

# Delete the old-name remote branch and push the new-name local branch:
git push origin :old-name new-name

source and more info

Fix error​

When doing git push origin :master main sometimes we get this error:

 ! [remote rejected] master (refusing to delete the current branch: refs/heads/master)
error: failed to push some refs to 'github.com:AlbertVilaCalvo/JavaScript-Udacity-Memory-Game.git'

This happens when eg we are renaming the branch master to main on a GitHub/Bitbucket repository that has master set as the default branch. To fix this, go to the GitHub website -> navigate to the repository -> Settings tab -> Branches, and change the 'Default branch'. After doing this, try again and it will work. (On Bitbucket, to change the default branch go to the repository -> Repository settings -> Repository details tab, expand the ADVANCED section and change 'Main branch'.)

Merge 2 git repositories​

From https://stackoverflow.com/a/10548919/4034572

Merge project-A into project-B.

cd /path/to/project-B
git fetch /path/to/project-A main
git merge --allow-unrelated-histories FETCH_HEAD

Be careful with conflicts! Eg if both projects have a README.md, it's better to re-name one of them first (do commit), otherwise you'll have to deal with conflicts.

To put project-A into a subfolder of project-B in a simple way, before running the commands above, first create a folder inside project-B, move all the files there, and then commit. Afterwards run the commands above.

--allow-unrelated-histories documentation: https://git-scm.com/docs/git-merge#Documentation/git-merge.txt---allow-unrelated-histories

Ignore mass reformatting with --ignore-rev and git config blame.ignoreRevsFile​

https://news.ycombinator.com/item?id=27643608

https://akrabat.com/ignoring-revisions-with-git-blame/

Config​

git config REFERENCE - https://git-scm.com/docs/git-config

Customizing Git - Git Configuration - https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration

Git Commands - Setup and Config - https://git-scm.com/book/en/v2/Appendix-C%3A-Git-Commands-Setup-and-Config

There are 3 type of settings:

Locationgit config option
System-wide (applies to every user)/etc/gitconfig--system
User-specific~/.gitconfig--global
Repo-specific.git/config--local

Show global config:

git config --list
git config -l
less ~/.gitconfig
bat ~/.gitconfig
~/.gitconfig
[core]
        editor = emacs -nw
[user]
        name = Albert Vila Calvo
        email = my@email.com
[init]
        defaultBranch = main

First time setup​

Getting Started - First-Time Git Setup - https://git-scm.com/book/en/v2/Getting-Started-First-Time-Git-Setup

git config --global user.name "Albert Vila Calvo"
git config --global user.email my@email.com
git config --global core.editor "emacs -nw"
git config --global init.defaultBranch main
git config --global push.autoSetupRemote true

Change email on a specific repo only​

Useful if you are using your personal computer for work or vice versa.

git config --local user.email my@email.com

Change colors​

All the things that can be customized are listed at https://git-scm.com/docs/git-config. Search for eg "color.diff".

Accepted color values: https://git-scm.com/docs/git-config#Documentation/git-config.txt-color

You can give it numbers, from 0 to 255, using the ANSI 256-color mode. Tip: test the color with echo $(git config --get-color "" "120 bold reverse") color test $(git config --get-color "" reset) (source).

Default color values: https://shallowsky.com/blog/programming/gitcolors.html

diff​

Available slots:

[color "diff"]
    meta = blue

Diff customization​