git retrieve a single file

http://stackoverflow.com/questions/610208/how-to-retrieve-a-single-file-from-specific-revision-in-git

git checkout 08618129e66127921fbfcbc205a06153c92622fe -- [full/path]

To clarify with an example:

git checkout mybranchname ~/src/myapp/myfile.txt

In my case, I need to roll back netwk_aging_sim.v0.1.R.

$ git checkout 4bb272d6a304168fc6711479a8b0b34c55e47182 netwk_aging_sim.v0.1.R
It worked.

The longnumber (branchname?) was found here: