Git has two basic commands that apply patches. The higher-level porcelain command, git am, is partially implemented in terms of the plumbing command git apply.
The command git apply is the workhorse of the patch application procedure. It accepts git diff- or diff- style output and applies it to the files in your current working directory. Though different in some key respects, it performs essentially the same role as Larry Wall’s patch command.
Because a diff contains only line-by-line edits and no other information (such as author, date, or log message), it cannot perform a commit and log the change in your repository. Thus, when git apply is finished, the files in your working directory are left modified. (In special cases, it can use or modify the index as well.)
In contrast, the patches formatted by git format-patch, either before or after they have been mailed, contain the extra information necessary to make and record a proper commit in your repository. Although git am is configured to accept patches generated by git format-patch, it is also able to handle other patches if they follow some basic formatting guidelines.
Note that the command git am creates commits on the current branch.
Let’s complete the patch generation-mail-apply process example using the same repository from Generating Patches. One developer has constructed a complete patch set, 0001-B.patch through 0007-F.patch, and has sent it or otherwise made it available to another developer. The other ...