First, the author is not necessarily the same as the committer. Git tracks both.
To set what name to use for just this repository, you could do:
git config user.name "Your Name"
git config user.email "Your email"
Notice the absence of the --global option. This will set the configuration in this repository only.
Alternatively, you can do this for only a single command, using the -c option:
git -c "user.name=Your Name" -c "user.email=Your email" commit ...
But I think it’s better to just use the config options above.