Some git commands and scripts that come in handy from time to time.

Splitting Repositories

You start with a small project. It grows over time as you add more and more features. And then, at some point, you realize one of these features should actually have been a separate repository because it provides functionality that can be useful in multiple contexts.

So far I moved the files and did a git init. At this point, I was always sad because well, I lost the history of the feature. Not only less commits for my Github statistics but I also lost git blame so it could no longer tell me why a particular algorithm was written the way it was.

Turns out git allows you to have your cake and eat it too!

# DEPRECATED!!
git filter-branch --prune-empty --subdirectory-filter src master

These days you get a deprecation warning when using filter-branch and are pointed to a third party package instead:

newren/git-filter-repo : Quickly rewrite git repository history (filter-branch replacement)

git-filter-repo(1) docs

# Requires git >= 2.24.0 and Python >= 3.5
pip3 install git-filter-repo
git filter-repo -h
git filter-repo --path src --subdirectory-filter src

Locking out package-lock.json

These days each npm install makes a git diff on frontend projects a real drag. Page upon page of uninteresting changes.

git diff -- ':!*package-lock.json' ':!*yarn.lock'

Or as a ~/.gitconfig alias:

df = "!f() { git diff --ignore-all-space -- $1 ':(exclude)*yarn.lock' ':!**package-lock.json'; }; f"

Important note: If you use the git df alias, git df package-lock.json will never show anything. You’ll have to use plain old git diff for checking the excluded files!

Deleting merged branches

Locally:
~/.gitconfig aliases. (develop|master): Do not delete these branches even if merged with current branch.

merged-branches = !git branch --merged | egrep -v \"(\\*| ) (develop|master)\" | xargs -n 1
dm = !git merged-branches git branch -d

Remote:

Somehow a CI server always seems to be amassing feature branches. A simple cleanup script to the rescue!

Replace name-committer (author filter) and origin (remote filter) and add as a ~/.gitconfig alias:

my-merged-remote-branches = !git for-each-ref --format='%(authorname):%(refname)' | egrep \"name-committer\" | egrep \"refs/remotes\" | sed -e \"s/^.*:refs\\/remotes\\/origin\\//:/\"

Followed by PowerShell:

git my-merged-remote-branches | % { git push --no-verify origin $_ }

Filename case renaming

Pesky Windows.
Also note the core.ignorecase configuration value.

git mv -f OldFileNameCase newfilenamecase

Remapping remote urls

When the remote url changes for all your repositories.

$paths = Get-ChildItem "c:\git-repos" | ? { $_.PSIsContainer }
foreach ($path in $paths) {
    $gitPath = Join-Path $path.FullName "\.git"
    if (Test-Path -Path $gitPath -PathType Container) {
        Write-Host $path.FullName " -> " $gitPath
        $url = "https://new-base-url.com/$($path.Name)"
        Write-Host "Remap to $url"
        Push-Location $path.FullName
        git remote set-url origin $url
        Write-Host " "
        Pop-Location
    }
}

Create PR in browser

From your current branch.

function Create-PullRequest() {
  $baseUrl = git remote get-url origin

  if ($baseUrl -match 'github.com') {
    $urlTemplate += "{base-url}/compare/{target-branch}...{source-branch}"
  } else {
    $urlTemplate += "{base-url}/pullrequestcreate?sourceRef={source-branch}&targetRef={target-branch}"
  }

  $sourceBranch = git rev-parse --abbrev-ref HEAD
  # $targetBranch = "develop"
  $targetBranch = "master"

  git push -u origin $sourceBranch
  start $urlTemplate.Replace("{base-url}", $baseUrl).Replace("{source-branch}", [uri]::EscapeDataString($sourceBranch)).Replace("{target-branch}", $targetBranch)
}

Set-Alias pr Create-PullRequest

Other blog posts

• git assume unchanged
• git hooks with Husky