How do you commit code as a different user?

Question

I want to be able to do this for a script. I'm essentially re-creating the entire version history of some code in Git - it currently uses a different version control system. I need the script to be able to add in the commits to Git while preserving the commit's original author (and date).

Assuming I know the commit author and the date/time the change was made, is there a Git command that allows me to do this? I'm assuming there is, because git-p4 does something similar. I'm just asking for the best way to do it.

Solution 1

Check out the --author option for git commit:

From the man page:

--author=<author>

Override the commit author. Specify an explicit author using the standard A U Thor <[email protected]> format. Otherwise <author> is assumed to be a pattern and is used to search for an existing commit by that author (i.e. rev-list --all -i --author=<author>); the commit author is then copied from the first such commit found.

Solution 2

Just to add to this: The --author option mentioned in the accepted answer will only override the author, not the committer information of the commit.

That is the correct behavior in most cases, but if for some reason you need to manually override the committer information as well, use the GIT_COMMITTER_NAME and GIT_COMMITTER_EMAIL environment variables (there is a GIT_COMMITTER_DATE as well). See Git-Internals-Environment-Variables

$ GIT_COMMITTER_NAME="New Name" GIT_COMMITTER_EMAIL="[email protected]" git commit --author="New Name <[email protected]>"

This will make the commit look like it was authored and committed by the specified user.

Solution 3

Use -c option along with git-commit to override any previous configuration. It will not touch your global/project configuration. For example, to override name and email:

git -c user.name='My Name' -c user.email='[email protected]' commit -m "Custom message"

However, if you intend to keep it as an additional setting, I would suggest to use an alias. Edit your ~/.gitconfig file and append a new alias for each non-default user and email.

[user]
  name = My Name
  email = [email protected]

[alias]
  commit-x = -c user.name='My X Name' -c user.email='[email protected]' commit
  commit-y = -c user.name='My Y Name' -c user.email='[email protected]' commit
  commit-z = -c user.name='My Z Name' -c user.email='[email protected]' commit

Alias will be applied globally. Test it.

git commit -m "Custom message with committer and author My Name <[email protected]>"
git commit-x -m "Custom message with committer and author My X Name <[email protected]>"
git commit-y -m "Custom message with committer and author My Y Name <[email protected]>"
git commit-z -m "Custom message with committer and author My Z Name <[email protected]>"

Comments

[Chris Johnsen]

Also, the --date option to override the date.

[studgeek]

Can you give a specific example, everything I try

[Roman]

@Tim Henigan: It looks like documentation is now hosted on Github so the man page link you posted is dead. Can you confirm the new page is the same thing (in case there are other answers that need links updated)?

[Tim Henigan]

@R0MANARMY: I updated the URL. The GitHub pages are correct. I updated my link since the man pages are no longer hosted on kernel.org. Thanks for letting me know about the change.

[Carl]

Here is what I ended up using: git commit -a --author="$user_details" --date="submit_date $submit_time" --file=/tmp/commit_msg

[bluenote10]

... and to see the difference: git log --pretty=fuller

[ksp]

Perfect. This is what I wanted and I could have never find the git internals man page.

[Arnab Biswas]

I get an error: "fatal: Option -m cannot be combined with -c/-C/-F." On removing "-m", getting another error: "fatal: could not lookup commit user.email=<provided_user_name>"

[BeardOverflow]

@ArnabBiswas Thanks for your feedback. I have just edited my answer because I had typed the first example wrongly: commit must go after of config options.

[frmbelz]

Another way to see the difference: git log --pretty='%cn %cd - %an %ad' HEAD where %cn %cd - committer name, date and %an %ad - author name, date.