GIT

GIT version management snippets.

Global Settings

Rebasing when pulling makes the branch history cleaner, avoiding pull merge commits. Prune on fetch automatically clean Git objects in your repository locally whenever you fetch changes from remote, minimizes the number of branches on your local machine. Highlight moved code block sections.

git config --global pull.rebase true
git config --global fetch.prune true
git config --global diff.colorMoved zebra

Use GPG keys with GIT tools for Commit Signing

# Get keys to use
gpg --list-keys

git config --global commit.gpgsign true
git config --global gpg.program /usr/bin/gpg
git config --global user.signingkey {KEY}

# Manually sign without settings above.
git tag -s {TAG}{COMMIT}

Revert Changes and Keep Commit History

git revert --no-edit {LAST GOOD COMMIT}..{LAST BAD COMMIT}

Force Repository to Previous Commit

Danger

git reset --hard {COMMIT ID}
git push --force origin master

This is data destructive. Ensure any files are cleaned up before committing.

Currently checked out versions of this repository will break.

Force Pull from Master Repository

Forces local repository to be in sync with master, discarding all local changes and un-pushed commits.

git fetch --all
git reset --hard origin/master

# Apply to a branch only
git checkout {BRANCH}
git fetch --all
git branch {BRANCH}-backup
git reset --hard origin/{BRANCH}

Revert Entire Directory to HEAD

git checkout -- {DIR}  # {DIR}/.. target everything in directory.
git clean -fd {DIR}  # {DIR}/.. target everything in directory.

Add Tag to Previous Commit

git pull --tags
git tag {TAG} {COMMIT}
git push --tags

Squash Commits to a Single Commit (Rebase)

This will squash a series of commits into a single commit, which is useful to cleanup multiple commits before pushing upstream.

Note

git rebase --interactive {COMMIT}

The COMMIT is the last commit that should be collapsed (e.g. rolled into a single commit).

Editor will appear with rebase configuration. Generally use pick for the first commit and squash for the remaining commits.

Note

git rebase --continue

If done correctly, this will show all commit messages that were rolled up. Update as needed and commit as normal.

Modify Specific Historical Commit

Warning

This will re-write commit history from the changed commit. Tags and releases will need to be deleted and re-created. Existing clones will break. Be careful.

git rebase --interactive '{COMMIT}^'  # Rebase one commit **before** change.

Note

Set edit for the desired commit; save and exit. Make desired changes.

git commit --all --amend --no-edit  # Finish rebasing to HEAD
git rebase --continue

# Reset affected tags
git tag -l
git rev-list -n 1 {TAG}
git tag -d {TAG}
git push --delete origin {TAG}
git tag {TAG} {NEW COMMIT HASH}
git push --tags

Warning

Ensure affected releases, tags are removed before pushing the changed repo.

Remove Tracked Files without Deleting Them

git rm --cached {FILE TO REMOVE FROM COMMIT}  # Single file.
git rm --cached {FILE1} {FILEN}  # Multiple files.
git rm -r --cached {DIR}  # All contents of a directory.

Highlight Changes in Long Single Lines

git diff --word-diff {FILE} {FILE}

Migrate git stash to another machine

Export a stash as a patch to import in another git client.

git stash show "stash@{0}" -p > changes.patch  # Export stash 0 to a patch.
git apply changes.patch  # Import patch to client.
git apply changes.patch --reverse  # Patch can be reverted if there are issues.

Repo git hooks

Hooks are located in .git/hooks but are not versioned. This enables repository tracked hooks. See .git/hooks for examples. Hooks must have exact names.

Ensure ansible vault files are encrypted on commit.

.githooks

0644 {USER}:{USER}

#!/usr/bin/env bash
#
# Called by "git commit" with no arguments.  The hook should
# exit with non-zero status after issuing an appropriate message if
# it wants to stop the commit. See .git/hooks for examples.

# Unset variables produce errors
set -u

if git rev-parse --verify HEAD >/dev/null 2>&1
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# Redirect output to stderr.
exec 1>&2

EXIT_STATUS=0

# Check that vault files are encrypted.
# read: -r do not allow backslashes to escape characters; -d delimiter
while IFS= read -r -d $'\0' file; do
    [[ "$file" != *.vault &&
         "$file" != *.vault.yml &&
         "$file" != *vault ]] && continue
    # cut gets symbols 1-2
    file_status=$(git status --porcelain -- "$file" 2>&1 | cut -c1-2)
    file_status_index=${file_status:0:1}
    file_status_worktree=${file_status:1:1}
    [[ "$file_status_worktree" != ' ' ]] && {
        echo "ERROR: *.vault file is modified in worktree but not added to the index: $file"
        echo "Can not check if it is properly encrypted. Use git add or git stash to fix this."
        EXIT_STATUS=1
    }
    # check is neither required nor possible for deleted files
    [[ "$file_status_index" = 'D' ]] && continue
    head -1 "$file" | grep --quiet '^\$ANSIBLE_VAULT;' || {
        echo "ERROR: non-encrypted *.vault file: $file"
        EXIT_STATUS=1
    }
done < <(git diff --cached --name-only -z "$against")

exit $EXIT_STATUS

mkdir {REPO}/.githooks
# Set local gitconfig hookspath to custom location.
git config -f .gitconfig core.hooksPath .githooks

.. literalinclude:: source/pre-commit
  :caption: **0755 {USER}:{USER}** **.githooks/pre-commit``

# Use a Makefile or manually run on repo checkout to setup.
git config --local include.path ../.gitconfig

Note

Command executes from .git directory, hence going up a directory to read the config.

List All Repositories for An Organization/User

Useful for determining if there are new repositories to sync.

# List all repositories for an organzation.
curl "https://api.github.com/orgs/{ORGANIZATION NAME}/repos?per_page=1000&page=1" | jq -r '.[] | .name' | sort

# List all repositories for a user.
curl "https://api.github.com/users/{USER}/repos?per_page=1000&page=1" | jq -r '.[] | .name' | sort