arc:tldr:b681b

The command arc amend is typically used in a version control system called Phabricator or Diffusion and is used to amend or modify an existing commit.

When you make changes to a codebase, you often create multiple commits to track the changes you make over time. However, sometimes you may want to make changes to a commit that you have already created. Instead of creating a new commit for these changes, arc amend allows you to modify the existing commit.

Here's how the arc amend command works:

1. You make changes to your code files as necessary.
2. After making the changes, stage the modified files using a command like git add . or hg add.
3. Run arc amend command. This will bring up an editor with the commit message of the previous commit (the one you want to amend).
4. Modify the commit message if needed or simply save and close the editor if you don't want to change the message.
5. The changes you made will be incorporated into the previous commit, effectively amending it.

arc amend is useful when you want to add or modify small changes to a commit without creating a new one. It helps in keeping the commit history clean and avoids creating unnecessary commit noise.