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'.

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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.)

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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.

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on Mac OS X (BSD find): Same effect as the accepted answer.

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

man find says -E uses extended regex support

NOTE: the .*/ prefix is needed to match a complete path:

For comparison purposes, here's the GNU/Linux version:

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

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Simple way - you can specify .* in the beginning because find matches the whole path.

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

find version

$ find --version
find (GNU findutils) 4.6.0
Copyright (C) 2015 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.
Features enabled: D_TYPE O_NOFOLLOW(enabled) LEAF_OPTIMISATION 
FTS(FTS_CWDFD) CBO(level=2)

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Try to use single quotes (') to avoid shell escaping of your string. Remember that the expression needs to match the whole path, i.e. needs to look like:

 find . -regex '\./[a-f0-9-]*.jpg'

Apart from that, it seems that my find (GNU 4.4.2) only knows basic regular expressions, especially not the {36} syntax. I think you'll have to make do without it.

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You should use absolute directory path when applying find instruction with regular expression. In your example, the

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

should be changed into

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

In most Linux systems, some disciplines in regular expression cannot be recognized by that system, so you have to explicitly point out -regexty like

find . -regextype posix-extended -regex "[a-f0-9\-]\{36\}\.jpg"

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If you want to maintain cross-platform compatibility, I could find no built-in regex search option that works across different versions of find in a consistent way.

Combine with grep

As suggested by @yarian, you could run an over-inclusive find and then run the output through grep:

find . | grep -E '<POSIX regex>'

This is likely to be slow but will give you cross-platform regex search if you need to use a full regular expression and can't reformat your search as a glob

Rewrite as a glob

The -name option is compatible with globs which will provide limited (but cross-platform) pattern matching.

You can use all the patterns that you would on the command line like * ? {} **. Although not as powerful as full regex, you might be able to reformulate your search to globs depending on your use-case.

Internet search for globs - many tutorials detailing full functionality are available online

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One thing I don't see covered is how to combine regular expressions with regular find syntax.

Eg: I want to find core dump files on BSD / Linux, I change to the root I want to scan.. eg: cd / then execute:

find \( -path "./dev" -o -path "./sys" -o -path "./proc" \) -prune -o -type f -regextype sed -regex ".*\.core$" -exec du -h {} \; 2> /dev/null

So I am using the prune command to exclude multiple system directories, before doing regular expression on the remaining files. Any error output (stderr) is deleted.

The important part is to use the Find syntax first, then OR (-o) with the regular expression.

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