GitHub Gists are full Git repositories, and can be cloned and pushed to.
You can clone them anonymously (read-only) just using their URL:
git clone https://gist.github.com/simonw/0a30d52feeb3ff60f7d8636b0bde296b
But if you want to be able to make local edits and then push them back, you need to use this recipe instead:
git clone [email protected]:0a30d52feeb3ff60f7d8636b0bde296b.git
You can find this in the "Embed" menu, as the "Clone via SSH" option.
This only uses the Gist's ID, the simonw/
part from the URL is omitted.
This uses your existing GitHub SSH credentials.
You can then edit files in that repository and commit and push them like this:
cd 0a30d52feeb3ff60f7d8636b0bde296b
# Edit files here
git commit -m "Edited some files" -a
git push