How can I retrieve the absolute filename in a shell script on Mac OS X?

Question

I'd like to retrieve the absolute file name of the script file that's currently executed. Links should be resolved, too.

On Linux, this seems to be done like this:

$(readlink -mn "$0")

but readlink seems to work very differently on Mac OS X.

I've read that this is done using

$(realpath $0)

in BSD but that doesn't work, either. Mac OS X does not have realpath.

Any idea?

ericslaw · Answer 1 · 2009-07-13 21:09:03Z

up vote 6 down vote accepted

I cheat and use perl for this very thing:

#!/bin/bash
dirname=`perl -e 'use Cwd "abs_path";print abs_path(shift)' $0`
echo $dirname

You'd think I'd just write the entire script in perl, and often I do, but not always.

answered Jul 13 '09 at 21:09

	This works, thanks a lot. I'll give you an upvote as soon as I can. Does anyone have a "pure shell" way of doing this? – Huxi Jul 13 '09 at 21:17
	I'm afraid this is as good as it gets. (Given the many multiple-line "pure shell" hacks one can find on Google.) – Arjan Jul 13 '09 at 21:34
	another possibility (though ugly) is to traverse the '..' path, memorizing (thru recursion or an array) until '..' returns the same file you just had (ie: you are at the top), then come back assembling the path as you go. I've seen Legato's Networker backup software doing this during strace as a method of obtaining a 'true' path (but perhaps not absolute). But it would be a lot more code than the above. – ericslaw Jul 14 '09 at 2:56

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