> Note also that if you're using a deficient shell that supports neither `printf %q` nor `${var@Q}` it's still easy to do quoting in `sed`. GNU `./configure` scripts do this internally, including special-casing to only quote the right side of `--arg=value`.

With the assumption that:

1. The person knows to do this weird thing 2. They do it consistently every time 3. They never forget

Also not sure how to use those solutions for the popen() example you provided.

The correct way is:

    subprocess.run([
       "gzip",
       "-c",
       "—-to-stdout",
       user_input
    ], stdout=open("foo.gz"))

And now I don’t have to worry about any of these weird things