How to use regex with find command?

find . -regextype sed -regex ".*/[a-f0-9\-]\{36\}\.jpg"

Note that you need to specify .*/ in the beginning because find matches the whole path.

Example:

susam@nifty:~/so$ find . -name "*.jpg"
./foo-111.jpg
./test/81397018-b84a-11e0-9d2a-001b77dc0bed.jpg
./81397018-b84a-11e0-9d2a-001b77dc0bed.jpg
susam@nifty:~/so$ 
susam@nifty:~/so$ find . -regextype sed -regex ".*/[a-f0-9\-]\{36\}\.jpg"
./test/81397018-b84a-11e0-9d2a-001b77dc0bed.jpg
./81397018-b84a-11e0-9d2a-001b77dc0bed.jpg

My version of find:

$ find --version
find (GNU findutils) 4.4.2
Copyright (C) 2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Eric B. Decker, James Youngman, and Kevin Dalley.
Built using GNU gnulib version e5573b1bad88bfabcda181b9e0125fb0c52b7d3b
Features enabled: D_TYPE O_NOFOLLOW(enabled) LEAF_OPTIMISATION FTS() CBO(level=0) 
susam@nifty:~/so$ 
susam@nifty:~/so$ find . -regextype foo -regex ".*/[a-f0-9\-]\{36\}\.jpg"
find: Unknown regular expression type `foo'; valid types are `findutils-default', `awk', `egrep', `ed', `emacs', `gnu-awk', `grep', `posix-awk', `posix-basic', `posix-egrep', `posix-extended', `posix-minimal-basic', `sed'.

The -regex find expression matches the whole name, including the relative path from the current directory. For find . this always starts with ./, then any directories.

Also, these are emacs regular expressions, which have other escaping rules than the usual egrep regular expressions.

If these are all directly in the current directory, then

find . -regex '\./[a-f0-9\-]\{36\}\.jpg'

should work. (I'm not really sure - I can't get the counted repetition to work here.) You can switch to egrep expressions by -regextype posix-egrep:

find . -regextype posix-egrep -regex '\./[a-f0-9\-]{36}\.jpg'

(Note that everything said here is for GNU find, I don't know anything about the BSD one which is also the default on Mac.)

Judging from other answers, it seems this might be find's fault.

However you can do it this way instead:

find . * | grep -P "[a-f0-9\-]{36}\.jpg"

You might have to tweak the grep a bit and use different options depending on what you want but it works.