How to apply a git patch from one repository to another?

If manually editing the patch file is out of the question or infeasible, this can be done with standard options (available in git apply, git format-patch and GNU patch).

1. -p<n> removes n leading directories from the paths in the patch.

2. After processing -p, --directory=<root> prepends root to each of the paths in the patch before applying.

Example

So, for your example, to take a patch that was originally on static/playdar.js and apply it to lib/playdar.js, you would run:

$ cat patch_file | git am     \ 
          -p1                 \ # remove 1 leading directory ('static/')
         --directory='lib/'     # prepend 'lib/'