realpath (and friends) in pure bash about pure-bash-bible

[pjeby]

They don't handle multiple trailing slashes correctly. Try strings like:

• abc//
• //xyz/..//abc//

etc. There might be other problems, I'm not sure. It's hard to do it right without using regular expression matching.

If you want to programmatically generate test cases, check out this bit of bashup/realpath's test suite: just a few lines that generate around 700 different test paths to compare the function vs. the real thing.

[pjeby]

Possibly worth noting is that the dirname and basename recipes given here aren't actually replacements for the dirname and basename commands. The real dirname command doesn't include a trailing /, and it returns . for a plain name, e.g. the real dirname foo returns ., but the emulation here doesn't. Similarly, the real basename command will strip multiple trailing slashes, but the emulation doesn't.

It might be worth adapting the emulations of dirname and basename from realpaths, as they're still one-liners of pure bash, but are tested to be exact equivalents to the original commands, across quite a few scenarios that the emulations here aren't valid for.

[dylanaraps]

@pjeby, both basename and dirname in the bible match their external utilities 1:1 now. If you can reproduce cases in which they don't, I'd love to know.

[pawamoy]

Closing, feel free to reopen.