> Am 21.07.2016 um 23:38 schrieb Bob Proulx <b...@proulx.com>: > > Reuti wrote: >> While we are on this: wondering about the difference about -h and -L I found >> that `man test` outputs on OS X: >> >> " -h file True if file exists and is a symbolic link. This >> operator is retained for compatibility with pre- >> vious versions of this program. Do not rely on its >> existence; use -L instead." >> >> while on Linux `man test` just states that it's the same. Is there any >> preference which one should be used for the bash builtin? > > Originally Unix did not provide symlinks. Then when symlinks were > added they were not completely added in a uniform regular way through > every command. Bummer! > > The original option letter used by test to check for the presence of a > symlink was -h. I don't know why. But in those days the only test > option to test for a symlink was -h. The -L came later. This legacy > is still visible in the HP-UX test man page for example. No -L > documented there. > > http://nixdoc.net/man-pages/HP-UX/man1/test.1.html > > However note that because POSIX requires it the /bin/sh posix shell > must implement -L as identical to -h. And the reverse. Therefore you > are safe to use either on any POSIX system. Remember too that POSIX > wasn't originally meant as a design document but as an OS feature > non-proliferation treaty to make it possible to write portable > programs. POSIX features must be present on any POSIX system and > therefore you can use the feature and expect it to work.
Thx for this historical digest. -- Reuti > If you need to interact with legacy systems which predate POSIX and > have never been updated to comply then you must use -h because that is > all there is there. But if you never interact with anything non-POSIX > then using -L is okay too. Either is the same as the other now. > > I think the statement in the Apple man page is there because someone > liked -L over -h and wanted to scare everyone into using one over the > other. But there isn't any reason to do so. > > Bob >
