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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

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

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

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 with message

git stash push -m "Some message"

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

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