I don’t have ed installed (not a conscious decision), which prevents this from working:
% patch<evil.patch sh: 1: ed: not found patch: ed FAILED
patch works just fine for me, though, so ed is not required.
% patch<evil.patch sh: 1: ed: not found patch: ed FAILED
patch works just fine for me, though, so ed is not required.
For patch to work correctly you have to allow executing ed commands (internally or by spawning ed) but for security reasons you better not let ed execute yet another program.
(I don't think I've ever used a system that didn't have ed installed by default.)
It is available in the packages, of course.
Which is sad because technically POSIX wants ed installed so purely technically, those distros aren't fully POSIX compliant.