/git-hacks

Some git hacks that everyone should know at some point in their dev lives

Some Git-related hacks for the daily struggles of the developer

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Git commits

Git commits are the best friends of developers, either they are working with others or not. Git commits must follow a pattern and must be "atomic".

Some rules of thumb:

  • Separate subject from body with a blank line
  • Limit the subject line to 50 characters
  • Capitalize the subject line
  • Do not end the subject line with a period
  • Use the imperative mood in the subject line (clean your room, close the door, take out the trash) 
    if applied, this commit will ________
Examples:
if applied, this commit will clean your room
if applied, this commit will close the door
if applied, this commit will take out the trash
    Obs 👉🏻: Remember: Use of the imperative is important only in the subject line. You can relax this restriction when you’re writing the body.
  • Wrap the body at 72 characters
  • Use the body to explain what and why vs. how

How to git rebase

First, verify your git logs:

git log --all --decorate --oneline --graph

Then, you need to select the commit ID right before the commit you want to change.

In the image above, we want to change the commit "Page Navigation View", then we need to rebase to the commit "Add routes for navigation" which is the commit right before.

After that, do:

git rebase -i <commit-id>

This will launch your default editor (vi/vim/nano) and you'll be presented with some options that look like the ones below:

pick 4155df1cdc7 Page Navigation View
pick c22a3fa0c5c Render navigation partial
pick aa0a35a867e Add styles for navigation

# Rebase 8d74af10294..aa0a35a867e onto 8d74af10294 (3 commands)
#
# Commands:
# p, pick = use commit
# r, reword = use commit, but edit the commit message
# e, edit = use commit, but stop for amending
# s, squash = use commit, but meld into previous commit
# f, fixup = like "squash", but discard this commit's log message
# x, exec = run command (the rest of the line) using shell
# d, drop = remove Git commit
#
# These lines can be re-ordered; they are executed from top to bottom.
#
# If you remove a line here THAT COMMIT WILL BE LOST.
#
# However, if you remove everything, the rebase will be aborted.
#
# Note that empty commits are commented out

Change from "pick" to "edit" for the commit you want to change. In our case, it'd be:

pick 4155df1cdc7 Page Navigation View  -> edit 4155df1cdc7 Page Navigation View

Tip 💡: In vi you can edit a file by pressing i. When you've edited what you wanted, press ESC. To quit and save the file, wq.

After that,

git add .
git rebase --continue

It'll ask for some merge changes. Select the ones you want to maintain (fix merge issues) and then keep doing git rebase --continue until you find yourself at the HEAD. When you're there:

git push --force-with-lease

How to git squash/fixup

It's mainly used to combine commits.

This is usual when we do a lot of "fix" git commit messages and then it becomes a mess. Start by calling our well-known git rebase -i to some commit-id and then change from "pick" to either "squash" or "fixup".

The difference between them are:

  • squash: keeps the gix fix commit messages in the description.
  • fixup: forget the commit messages of the fixes and keep the original.

First get the commit-id you want to rebase to:

 git log --all --decorate --oneline --graph
 git rebase -i <commit-id>

Example:

pick 4155df1cdc7 Page Navigation View
pick c22a3fa0c5c Render navigation partial
pick aa0a35a867e Add styles for navigation
pick 62e858a322 Fix a typo
pick 5c25eb48c8 Ops another fix
pick 7f0718efe9 Fix 2
pick f0ffc19ef7 Argh Another fix!

Now if you wanna combine the fixes into c22a3fa0c5c Render navigation partial, you should:

  • move the fixes up so that they are right below the commit you want to keep in the end;
  • change pick to squash or fixup for each of the fixes.

And then you'll end up with something like:

pick 4155df1cdc7 Page Navigation View
pick c22a3fa0c5c Render navigation partial
fixup 62e858a322 Fix a typo
fixup 5c25eb48c8 Ops another fix
fixup 7f0718efe9 Fix 2
fixup f0ffc19ef7 Argh Another fix!
pick aa0a35a867e Add styles for navigation

Save the changes and then git push --force-with-lease.

You'll end up with:

pick 4155df1cdc7 Page Navigation View
pick 96373c0bcf Render navigation partial
pick aa0a35a867e Add styles for navigation

Restarting a git commit history

Whenever we're working on, usually, a big project, there are some times that our git commit messages don't make sense. If you want to start from scratch while maintaning all your code, you can create a patch.

Basically a patch is a box containing all your code, but that can be transported to a new location.

Imagine you have a branch called add-page-navigation. Let's see the step-by-step to do that:

  1. Making sure your branch has all the changes present in the master and has no conflict with the same.

    • git rebase master while you're in add-page-navigation to get all the changes from master to your branch;

  2. Creating the patch file:

    git diff master add-page-navigation > ~/add_page_navigation.patch

    Once the command is run and you don't see any errors, the patch file is generated.

  3. Deleting the add-page-navigation branch:

    • check out to the master branch: git checkout master;
    • delete the add-page-navigation branch: git branch -D add-page-navigation;

  4. Creating a new branch with the same name:

    • while in the master branch, run git checkout -b add-page-navigation. At this point this is a fresh new branch with no differences from master branch

  5. Finally, apply your changes from the patch file:

    • while in the new created branch, run git apply ~/add_page_navigation.patch.

  6. Now commit each part of the code as you want.