fixing_common_mistakes.md

Fixing Common Mistakes

Joseph P. Vantassel, The University of Texas at Austin

Fixes that do not affect the history

Return to Last Commit

git status                       # Can see the files have changed
git diff                         # Can see the changes
git checkout <filename>          # Reset file to last commit
git status                       # Can see file has been rolled back
git diff                         # Can see there are no changes in file

Fixes that do affect the history

Amend Bad Commit Message

git log                         # Current log
git commit --amend -m "My Msg"  # Change commit message
git log                         # New log, see changed message, but new hash!
git pull                        # So git can resolve conflicts
git push                        # Push up to the remote

Forgot to Include File

git add <forgotten file>        # Place forgotten file in staging file
git commit --amend              # Going to amend
git log                         # See no new commit
git log --stat                  # See files that were changed in commit

Made Changes on Master By Mistake

First, copy the commit to the correct branch.

git log                         # Get hash for the bad commit
git checkout branch_name        # Go to the right branch
git log                         # Can see we don't have the commit
git cherry-pick hashmaster      # Brings commit onto feature branch
git log                         # See the copied commit

Second, remove the commit from the master branch. There are three ways of doing this they are a soft, mixed, and hard reset. You will typically only perform one of these three.

git checkout master             # Go back to the master branch
git log                         # Get hash of the bad commit
git reset --soft hash           # Soft: Commit gone, files are changed, and staged
git reset hash                  # Mixed: Commit gone, files are changed, but not staged
git reset --hard hash           # Hard: Commit gone, file changes gone
git clean -df                   # Remove all untracked (d for directories, f for files)

Accidental Hard Reset

There is some hope for this to be successful if the hard reset was done no longer than 30 days ago.

git reflog                      # This keeps track of all changes, might see hash
git checkout hash               # If see the hash you can time-warp back,
                                # but in a "detached head state" (not on a branch)
git log                         # Can now see the changes are back
git branch branchname           # Add a branch to save, if not it will be deleted
git branch                      # We can see our current branch and new branch
git checkout master             # Go to master
git branch                      # See all our branches, "detached head state" is gone

Committed a Large File by Accident

You accidentally committed a large file to your local repo but are now having an issue pushing your commit due to GitHub's maximum file size of 100MB.

When you push you will see an error like this:

remote: error: GH001: Large files detected. You may want to try Git Large File Storage
remote: error: Trace: <hash>
remote: error: See http://git.io/iEPt8g for more information.
remote: error: File <path> is 400.60 MB; this exceeds GitHubs file size limit of 100.00 MB
To github.com:username/repository.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to [email protected]:username/repository.git

Note: If you add this file to the repositories .gitignore and try committing again this will not solve your problem as the issue is with your first commit (the one before you realized you have that large file).

To fix this issue you need to not only .gitignore the large file, but also purge this file from your commit history so you can push your work and be up to update on your remote. You do this by going back in your tree and forcefully removing the file.

git filter-branch --tree-filter 'rm -rf path/to/your/large/file' HEAD

If you need to do this for more than one file, you will need to add a -f, to tell GitHub to force overwrite the backup it made when you performed the previous filter and removal, like this.

git filter-branch -f --tree-filter 'rm -rf path/to/your/other/large/file' HEAD

Renaming a Remote Repository

On GitHub

Your Repo > Settings > Repository name

Links to the previous name of your repository will be forwarded to your new repository. However, for clarity its recommend that you update your links.

git remote set-url origin <newurl>

Sources

Git Tutorial: Fixing Common Mistakes and Undoing Bad Commits

How to Remove a Big File Wrongly Commited