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Changing older or multiple commits - using rebase

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Command

git rebase

About

  • Changes the snapshot. New commits will replace the old
  • In standard mode, it allows you to literally rewrite history — automatically applying commits in your current working branch to the passed branch head
  • Process of moving or combining a sequence of commits to a new base commit.

In the above image, the green commits are formed after a rebase

  • Rebasing is changing the base of your branch from one commit to another making it appear as if you’d created your branch from a different commit

Rebase the current branch on master

git rebase master This will change the commits in such a way that it would appear that your current branch was created off the latest master commit

Two modes of git rebase

Manual / Standard

git rebase <baseBranch>
  • The above command will rebase your current branch onto the baseBranch
  • baseBranch can be any type of commit reference:
    • Branch name, a tag, commit ID, relative reference to HEAD
  • Rebasing means the current branch’s commits will be put on top of the baseBranch

Interactive mode

git rebase -i <baseBranch>
  • -i flag stands for interactive mode
  • Instead of blindly moving all of the commits to the new base, interactive rebasing gives you the opportunity to alter individual commits in the process.
  • It rebases the current branch onto baseBranch , but opens an editor where you can enter commands for each commit
    • These commands determine how individual commits will be transferred to the new base

Rebase commands

  • drop (d) - Discard the commit from the final combined commit block
  • pick (p) - Leaves the commit untouched. Will still be an individual commit in the branch’s history
  • exec (x) - executes a command line script on each marked commit
  • reword (r) - 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

Things to keep in mind

  • Commits modified with a rebase command have a different ID than either of the original commits.
  • Commits marked with pick will have a new ID if the previous commits have been rewritten.

Configuration options

The following rebase properties can be set using git config

  • rebase.stat - False by default. The option toggles display of visual diffstat content that shows what changed since the last rebase.
  • rebase.autoSquash - Boolean. Toggles the --autosquash behaviour
  • rebase.missingCommitsCheck - Change behaviour around missing commits. Multiple possible values:
    • warn - Prints warning output in interactive mode which warns of removed commits
    • error - Stops the rebase and prints removed commit warning messages
    • ignore - Set by default this ignores any missing commit warnings
  • rebase.instructionFormat - A git log format string that will be used for formatting interactive rebase display

Additional rebase flags

  • --continue - Advance the rebase after all conflicts are resolved
  • --abort - Reset the rebase. Cancel the rebase
  • --onto - Using git rebase onto

Are my commits gone when dropped in interactive mode?

No. Using git reflog can help restore those “lost” commits

Sources

Graph View

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