brandon/oam
1
0
Fork 0
mirror of https://gitea.com/mcereda/oam.git synced 2026-02-09 05:44:23 +00:00
Code Issues Packages Projects Releases Wiki Activity
Files
e0d49c95a6ec9ece1920166f9ef95b781aefc10e
oam/knowledge base/git.md
Michele Cereda e0d49c95a6 chore: containerized git server in turris os
2023-04-10 17:55:05 +02:00

29 KiB
Raw Blame History

Git

  1. TL;DR
  2. Authentication
  3. Configuration
    1. Remotes
      1. Push to multiple git remotes with the one command
    2. Aliases
  4. Manage changes
    1. Create a patch
    2. Apply a patch
  5. The stash stack
  6. Branches
    1. Checkout an existing remote branch
    2. Delete a branch
    3. Delete branches which have been merged or are otherwise absent from a remote.
    4. Merge the master branch into a feature branch
    5. Rebase a branch on top of another
  7. Tags
  8. Convert a normal repository to a bare one
  9. Prepare the git server
  10. LFS extension
  11. Submodules
  12. Remove a file from a commit
  13. Remove a file from the repository
  14. Troubleshooting
    1. Debug
    2. GPG cannot sign a commit
    3. Git does not accept self-signed certificates
  15. Further readings
  16. Sources

TL;DR

# Set your identity.
git config 'user.name' 'User Name'
git config --global 'user.email' 'user@email.com'

# Avoid issues when collaborating from different platforms.
git config --local 'core.autocrlf' 'input'
git config --local 'core.autocrlf' 'true'

# Create aliases.
git config --local 'alias.co' 'checkout'
git config --global 'alias.unstage' 'reset HEAD --'
git config 'alias.funct' '!f() { sh_command ; sh_command | sh_command ; } && f'

# Show git's configuration.
git config --list
git config --list --show-scope
git config --list --show-origin

# Render all current settings' values.
git config --list \
  | awk -F '=' '{print $1}' | sort -u \
  | xargs -I {} sh -c 'printf "{}=" && git config --get {}'

# Get a default value if the setting has none.
# Does not work on sections alone.
git config --get --default 'not-set' 'filter.lfs.cleaned'

# Create or reinitialize a repository.
git init
git init --initial-branch 'main' 'path/to/repo'
git init --bare 'path/to/repo.git'

# Clone a repository.
git clone 'https://github.com:user/repo.git'
git clone --bare 'git@github.com:user/repo.git' 'path/to/clone'
git clone --recurse-submodules 'ssh@git.server:user/repo.git'
git clone --depth 1 'ssh@git.server:user/repo.git'
git clone 'https://token@github.com/user/repo'
git \
  -c http.extraHeader="Authorization: Basic $(echo -n "user:pat" | base64)" \
  clone 'https://dev.azure.com/org/project/_git/repo'

# Convert a normal repository to a bare one.
git clone --bare 'repository' 'path/to/bare/clone.git'

# Unshallow a clone.
git pull --unshallow

# Get objects and refs but do not incorporate them.
git fetch

# Get changes and merge them.
git pull --all
git pull --verify-signatures
git pull 'remote' 'branch'

# Show what files changed.
git status
git status --verbose

# Show changes in a repository.
git diff
git diff --staged 'commit_hash'
git diff 'commit_hash_1..commit_hash_2'
git diff 'branch_1' 'branch_2'
git diff --word-diff='color'
git log -p 'feature' --not 'master'

# Just show changes between two files.
git diff --no-index 'path/to/file/a' 'path/to/file/b'

# Stage changes for commit.
git add .
git add --all
git add 'path/to/file'

# Interactively review chunks of changes.
git add --patch 'path/to/file'

# Commit changes.
git commit --message 'message'
git commit --message 'whatever' --gpg-sign
git commit --allow-empty --allow-empty-message
git commit --date='Jun 13 18:30:25 IST 2015'
git commit --date="$(date --date='2 days ago')"

# Edit the last commit's message.
git commit --amend
git commit --amend --message 'message'

# Change the last commit's author.
git config 'user.name' 'user name'
git config 'user.email' 'user.email@mail.com'
git commit --amend --reset-author

# Sign the last commit.
git commit --amend --no-edit --gpg-sign

# Show commits which would be pushed.
git log @{u}..

# Revert a commit but keep the history of the event as a separate commit.
git revert 'commit_hash'

# Interactively rebase the last 7 commits.
git rebase -i '@~7'

# List remotes.
git remote --verbose

# Add a new remote.
git remote add 'gitlab' 'git@gitlab.com:user/repo.git'

# Set a new URL for an existing remote.
git remote set-url 'gitlab' 'git@gitlab.com:user/repo.git'

# Push committed changes.
git push
git push 'remote' 'branch_1' 'branch_N'
git push 'git@github.com:user/repo.git'
git push --all --force

# Show the repository's history.
git reflog
git log -p

# Visualize the repository's history.
git log --graph --full-history --all --color --decorate --oneline

# Show and verify signatures.
git log --show-signature -1

# Remove staged and working directory changes.
git reset --hard
git reset --hard 'origin/main'

# Go back 4 commits.
git reset --hard 'HEAD~4'

# Remove untracked files.
git clean -f -d

# Remove ignored files.
git clean -f -d -x

# Show who committed which line.
git blame 'path/to/file'

# List changed files in a given commit.
git diff-tree --no-commit-id --name-only -r 'commit_hash'

# Create patches.
git diff > 'file.patch'
git diff --output 'file.patch' --cached
git format-patch -5 'commit_hash'
git format-patch 'HEAD~3' -o 'dir'
git format-patch 'HEAD~2' --stdout > 'single/file.patch'

# Create a full patch of the unstaged changes.
git add . && git commit -m 'uncommitted' \
  && git format-patch 'HEAD~1' && git reset 'HEAD~1'

# Apply a patch to the current index.
git apply 'file.patch'

# Apply commits from a patch.
git am 'file.patch'

# Stash changes locally.
git stash
git stash push 'message'

# List all the stashed changes.
git stash list

# Apply the most recent change and remove them from the stash stack.
git stash pop

# Apply a stash, but don't remove it from the stack.
git stash apply stash@{6}

# Remove a single stash entry from the stash stack.
# Defaults to the current one.
git stash drop
git stash drop stash@{2}

# Remove all the stash entries.
# Those will then be pruned and may be impossible to recover.
git stash clear

# Apply only the changes made within a given commit.
git cherry-pick 'commit_hash'

# Create a branch.
git branch 'branch_name'
git switch -c 'branch_name'
git checkout -b 'local_branch_name' 'remote/branch_name'

# Create a bare branch without any commits.
git checkout --orphan 'branch_name'

# List branches.
git branch -a

# Rename a branch.
git branch --move 'old_name' 'new_name'

# Switch branches.
git switch 'branch_name'
git checkout 'branch_name'
git checkout -

# Set the current HEAD branch to track a remote branch.
git branch -u 'remote_name/upstream-branch'

# Get the current branch.
git branch --show-current         # git > v2.22
git rev-parse --abbrev-ref 'HEAD'

# Delete local branches.
git branch --delete 'branch_name'
git branch -D 'branch_name'

# Delete remote branches.
git push 'remote_name' ':branch_name'
git push 'remote_name' --delete 'branch_name'

# Delete both local and remote branches.
git branch --delete --remotes 'branch_name'

# Sync the local branch list.
git fetch --prune

# Remove all stale branches.
git remote prune 'branch_name'

# Delete branches which have been merged or are otherwise absent from a remote.
git branch --merged | grep -vE '(^\*|master|main|dev)' | xargs git branch -d
git fetch -p \
  && awk '/origin/&&/gone/{print $1}' <(git branch -vv) | xargs git branch -d

# List all tags.
git tag

# Create annotated tags.
git tag --annotate 'v0.1.0'
git tag -as 'v1.2.0-r0' -m 'signed annotated tag for v1.2.0 release 0'
git tag -a '1.1.9' '9fceb02'

# Create lightweight tags.
git tag 'v0.1.1-rc0'
git tag '1.12.1' 'HEAD'

# Push specific tags.
git push 'remote_name' 'v1.5'

# Push annotated tags only.
git push --follow-tags

# Push all tags.
git push --tags

# Delete local tags.
git tag -d 'v1.4-lw'

# Delete remote tags.
git push 'remote_name' --delete 'v1.4-lw'

# Sync the local tags list.
git fetch --prune-tags

# Rebase a branch on top of another.
git rebase 'branch_name'
git rebase 'remote_name/upstream_branch_name' 'local-branch_name'
git pull --rebase='interactive' 'remote_name' 'branch_name'

# Change the date of an existing commit.
git filter-branch --env-filter \
  'if [ $GIT_COMMIT = 119f9ecf58069b265ab22f1f97d2b648faf932e0 ]
   then
     export GIT_AUTHOR_DATE="Fri Jan 2 21:38:53 2009 -0800"
     export GIT_COMMITTER_DATE="Sat May 19 01:01:01 2007 -0700"
   fi'

# Sign all commits from now on.
git config --global 'user.signingKey' 'KEY_ID_IN_SHORT_FORMAT'
git config --local 'commit.gpgSign' true

# Import commits from another repo.
git --git-dir='path/to/other-repo/.git' format-patch -k -1 --stdout 'commit_hash' \
| git am -3 -k

# Get the top-level directory of the current repository.
git rev-parse --show-toplevel

# Update all submodules.
git submodule update --init --recursive

# Show the first commit that has the string "cool" in its message body.
git show :/cool

Authentication

# Use credentials in the URL.
git clone 'https://username:password@host/path/to/repo'
git clone 'https://token@github.com/user/repo'

# Use headers.
BASIC_AUTH='username:password'   # or 'username:token', or ':token'
BASIC_AUTH_B64="$(printf "$BASIC_AUTH" | base64)"
git \
  -c http.extraHeader="Authorization: Basic ${BASIC_AUTH_B64}"
  clone 'https://dev.azure.com/organizationName/projectName/_git/repoName'

Configuration

# Required to be able to commit changes.
git config --local 'user.email' 'me@me.info'
git config --local 'user.name' 'Me'

# Avoid issues when collaborating from different platforms.
# 'input' on unix, 'true' on windows, 'false' only if you know what you are doing.
git config --local 'core.autocrlf' 'input'

# Sign commits by default.
# Get the GPG key short ID with `gpg --list-keys --keyid-format short`.
git config --local 'user.signingKey' 'KEY_ID_IN_SHORT_FORMAT'
git config --local 'commit.gpgSign' true

# Pull submodules by default.
git config --global 'submodule.recurse' true

# Use a Personal Access Token to authenticate.
git config http.extraHeader="Authorization: Basic $(echo -n 'user:pat' | base64)"

To show the current configuration use the --list option:

git config --list
git config --list --show-scope
git config --list --global --show-origin

The configuration is shown in full for the requested scope (or all if not specified), but it might include the same setting multiple times if it shows up in multiple scopes.
Render the current value of a setting using the --get option:

# Get the current user.name value.
git config --get 'user.name'

# Render all current settings' values.
# Gets the settings names, then requests the current value for each.
git config --list \
  | awk -F '=' '{print $1}' | sort -u \
  | xargs -I {} sh -c 'printf "{}=" && git config --get {}'

Remotes

# Add a remote.
git remote add 'gitlab' 'git@gitlab.com:user/my-awesome-repo.git'

# Add other push URLs to an existing remote.
git remote set-url --push --add 'origin' 'https://exampleuser@example.com/path/to/repo1'

# Change a remote's URL.
git remote set-url 'origin' 'git@github.com:user/new-repo-name.git'

Push to multiple git remotes with the one command

To always push to repo1, repo2, and repo3, but always pull only from repo1, set up the remote 'origin' as follows:

git remote add origin https://exampleuser@example.com/path/to/repo1
git remote set-url --push --add origin https://exampleuser@example.com/path/to/repo1
git remote set-url --push --add origin https://exampleuser@example.com/path/to/repo2
git remote set-url --push --add origin https://exampleuser@example.com/path/to/repo3

[remote "origin"]
    url = https://exampleuser@example.com/path/to/repo1
    pushUrl = https://exampleuser@example.com/path/to/repo1
    pushUrl = https://exampleuser@example.com/path/to/repo2
    pushUrl = https://exampleuser@example.com/path/to/repo3
    fetch = +refs/heads/*:refs/remotes/origin/*

To only pull from repo1 but push to repo1 and repo2 for a specific branch specialBranch:

[remote "origin"]
    url = ssh://git@aaa.xxx.com:7999/yyy/repo1.git
    fetch = +refs/heads/*:refs/remotes/origin/*
    …
[remote "specialRemote"]
    url = ssh://git@aaa.xxx.com:7999/yyy/repo1.git
    pushUrl = ssh://git@aaa.xxx.com:7999/yyy/repo1.git
    pushUrl = ssh://git@aaa.xxx.com:7999/yyy/repo2.git
    fetch = +refs/heads/*:refs/remotes/origin/*
    …
[branch "specialBranch"]
    remote = origin
    pushRemote = specialRemote
    …

See https://git-scm.com/docs/git-config#git-config-branchltnamegtremote.

Aliases

Simple aliases to git commands can be added like aliases to a shell:

[alias]
  caa = commit -a --amend -C HEAD
  ls = log --oneline
  statsu = status

But simple aliases have limitations:

  • they can't have parameters
  • you can't execute multiple git commands in a single alias
  • you can't use | (pipes) or grep

git allows you to escape to a shell using ! (bang); this opens a new world of possibilities for aliases:

  • use shell expansions and parameters
  • use multiple git commands
  • use pipes and all command line tools

Those commands need to be wrapped into a one-line function definition:

[alias]
  new = !sh -c 'git log $1@{1}..$1@{0} "$@"'
  pull-from-all = "!f() { \
      git remote show \
      | xargs -I{} -P0 -n1 git pull {} ${1-$(git branch --show-current)} \
      ; } && f"
  subtree-add = "!f() { git subtree add --prefix $2 $1 master --squash ; } ; f"

Manage changes

# Show changes relative to the current index (not yet staged).
git diff

# Show changes in the staged files only.
git diff --staged

# Show changes relative to 'commit' (defaults to HEAD if not given).
# Alias of `--staged`.
git diff --cached 'commit_hash'

# Show changes relative to a different branch.
git diff 'branch_name'

# Show changes between commits.
# Separating the commits with `..` is optional.
git diff 'commit_hash_1' 'commit_hash_2'
git diff 'commit_hash_1..commit_hash_2'

# Show changes between branches.
# Separating the branches with `..` is optional.
git diff 'branch_name_1' 'branch_name_2'
git diff 'branch_name_1..branch_name_2'

# Show a word diff using 'mode' to delimit changed words for emphasis.
# 'mode' defaults to 'plain'.
# 'mode' must be one of 'color', 'none', 'plain' or 'porcelain'.
git diff --word-diff='porcelain'

# Just show changes between two files.
# DO NOT consider them part of of the repository.
# This can be used to diff any two files.
git diff --no-index 'path/to/file/A' 'path/to/file/B'

Create a patch

Just save the output from git diff to get a patch file:

# Just the current changes.
# No staged nor committed files.
git diff > 'file.patch'

# Staged files only.
git diff --output 'file.patch' --cached

The output from git diff just shows changes to text files by default, no metadata or other information about commits or branches.
To get a whole commit with all its metadata and binary changes, use git format-patch:

# Include 5 commits starting with 'commit' and going backwards.
git format-patch -5 'commit_hash'

# Include 3 commits starting from HEAD and save the patches in 'dir'.
git format-patch 'HEAD~3' -o 'dir'

# Include 2 commits from HEAD and save them as a single file.
git format-patch 'HEAD~2' --stdout > 'single/file.patch'

# Create a full patch of the unstaged changes.
git add . && git commit -m 'uncommitted' \
  && git format-patch 'HEAD~1' && git reset 'HEAD~1'

Apply a patch

Use git apply to apply a patch file to the current index:

git apply 'file.patch'

The changes from the patch are unstaged and no commits are created.
To apply all commits from a patch, use git am on a patch created with git format-patch:

git am 'file.patch'

The commits are applied one after the other and registered in the repository's logs.

The stash stack

The stash is a changelist separated from the one in the current working directory.
git stash will save the current changes there and cleans the working directory. You can (re-)apply changes from the stash at any time:

# Stash changes locally.
git stash

# Stash changes with a message.
git stash save 'message'

# List all the stashed changes.
git stash list

# Apply the most recent change and remove them from the stash stack.
git stash pop

# Apply a stash, but don't remove it from the stack.
git stash apply stash@{6}

Branches

Checkout an existing remote branch

This creates a local branch tracking an existing remote branch.

$ git checkout -b 'local-branch' 'remote/existing-branch'
Branch 'local-branch' set up to track remote branch 'existing-branch' from 'remote'.
Switched to a new branch 'local-branch'

Delete a branch

# Delete local branches.
git branch --delete 'local-branch'
git branch -D 'local-branch'

# Delete remote branches.
git push 'remote' ':feat-branch'
git push 'remote' --delete 'feat-branch'

# Delete both local and remote branches.
git branch --delete --remotes 'feat-branch'

Delete branches which have been merged or are otherwise absent from a remote.

Command source [here][prune local branches that do not exist on remote anymore].

# Branches merged on the remote are tagged as 'gone' in `git branch -vv`'s output.
git fetch -p \
  && awk '/origin/&&/gone/{print $1}' <(git branch -vv) | xargs git branch -d

# Retain the current, 'master', 'main' and 'dev*' branches in all cases.
git branch --merged | grep -vE '(^\*|master|main|dev)' | xargs git branch -d

Merge the master branch into a feature branch

git stash pull
git checkout 'master'
git pull
git checkout 'feature'
git pull
git merge --no-ff 'master'
git stash pop

git checkout 'feature'
git pull 'origin' 'master'

Rebase a branch on top of another

git rebase takes the commits in a branch and appends them on top of the commits in a different branch. The commits to rebase are previously saved into a temporary area and then reapplied to the new branch, one by one, in order.

# Rebase main on top of the current branch.
git rebase 'main'

# Rebase an upstream branch on top of a local branch.
git rebase 'remote/upstream-branch' 'local-branch'

# Rebase the current branch onto the *upstream* 'master' branch.
git pull --rebase='interactive' 'origin' 'master'

Tags

Annotated tags are stored as full objects in git's database:

# Create annotated tags.
git tag --annotate 'v0.1.0'

# Create and sign annotated tags.
git tag -as 'v1.2.0-r0' -m "signed annotated tag for v1.2.0 release 0"

# Tag specific commits.
git tag -a '1.1.9' '9fceb02'

# Push all annotated tags only.
git push --follow-tags

while lightweight tags are stored as a pointer to a specific commit:

# Create lightweight tags.
git tag 'v0.1.1-rc0'
git tag '1.12.1' 'HEAD'

Type-generic tag operations:

# Push specific tags.
git push 'origin' 'v1.5'

# Push all tags
git push --tags

# Delete specific local tags only.
git tag -d 'v1.4-lw'

# Delete specific remote tags only.
git push 'origin' --delete 'v1.4-lw'

Convert a normal repository to a bare one

The preferred method is to create a bare clone of the normal repository:

git clone --bare 'repository' 'repository.git'

Prepare the git server

  1. Create the git user:

    sudo adduser 'git'
sudo chsh 'git' -s "$(which 'git-shell')"

  2. (Optionally) create the service's directory:

    sudo mkdir '/srv/git'
sudo chown 'git' '/srv/git'

  3. Set up passwordless authentication:

    sudo mkdir '/home/git/.ssh' && sudo chmod '700' '/home/git/.ssh'
sudo touch '/home/git/.ssh/authorized_keys' && sudo chmod '600' '/home/git/.ssh/authorized_keys'
sudo chown -R 'git' '/home/git'

  4. (Optionally) create the bare project repository:

    Do this as the git user, or assign it permissions on the folders.

    git init --bare 'project.git'

# Or, if one wants the repository to reside in the service's directory:
git init --bare '/srv/git/project.git'

The project repository will be available for clients using the following:

git clone 'git@fqdn:project.git'

# Or, if the repository resides in the service's directory:
git clone 'git@fqdn:/srv/git/project.git'

LFS extension

  1. Install the extension:

    apt install 'git-lfs'
brew install 'git-lfs'
dnf install 'git-lfs'
pacman -S 'git-lfs'

  2. If the package manager did not enable it system-wide, enable the extension for your user account:

    git lfs install

    Without any options, this will only setup the "lfs" smudge and clean filters if they are not already set.

  3. Configure file tracking from inside the repository:

    git lfs track "*.exe"
git lfs track "enormous_file.*"

  4. Add the .gitattributes file to the traced files:

    git add '.gitattributes'
git commit -m "lfs configured"

Submodules

See Git Submodules: Adding, Using, Removing, Updating for more information.

# Add a submodule to an existing repository.
git submodule add 'https://github.com/ohmyzsh/ohmyzsh' 'lib/ohmyzsh'

# Clone a repository which has submodules.
git clone --recursive 'keybase://public/bananas/dotfiles'
git clone --recurse-submodules 'ohmyzsh' 'keybase://public/bananas/dotfiles'

# Update an existing repository which has submodules.
git pull --recurse-submodules

To delete a submodule the procedure is more complicated:

  1. De-init the submodule:

    git submodule deinit 'lib/ohmyzsh'

    This wil also remove its entry from $REPO_ROOT/.git/config.

  2. Remove the submodule from the repository's index:

    git rm -rf 'lib/ohmyzsh'

    This wil also remove its entry from $REPO_ROOT/.gitmodules.

  3. Commit the changes.

Remove a file from a commit

See remove files from git commit.

Remove a file from the repository

  1. Unstage the file using git reset; specify HEAD as the source:

    git reset HEAD 'secret-file'

  2. Remove the file from the repository's index:

    git rm --cached 'secret-file'

  3. Check the file is no longer in the index:

    $ git ls-files | grep 'secret-file'
$

  4. Add the file to .gitignore or remove it from the working directory.

  5. Amend the most recent commit from your repository:

    git commit --amend

Troubleshooting

Debug

When everything else fails, enable tracing:

export GIT_TRACE=1

GPG cannot sign a commit

error: gpg failed to sign the data
fatal: failed to write commit object

If gnupg2 and gpg-agent 2.x are used, be sure to set the environment variable GPG_TTY, specially zsh users using Powerlevel10k with Instant Prompt enabled.

export GPG_TTY=$(tty)

Git does not accept self-signed certificates

Disable certificate verification:

export GIT_SSL_NO_VERIFY=true
git -c http.sslVerify=false …

Further readings

Sources