linux find regex

Question

I'm having trouble using the regex of the find command. Probably something I don't understand about escaping on the command line.

Why are these not the same?

find -regex '.*[1234567890]'
find -regex '.*[[:digit:]]'

Bash, Ubuntu

What output do you have to indicate that they are not?

shellter
– shellter

2011-04-12 13:16:12 +00:00
Commented Apr 12, 2011 at 13:16 — shellter
– shellter, Commented Apr 12, 2011 at 13:16

bmk · Accepted Answer · 2011-04-12 13:15:41Z

73

You should have a look on the -regextype argument of find, see manpage:

      -regextype type
          Changes the regular expression syntax understood by -regex and -iregex 
          tests which occur later on the command line.  Currently-implemented  
          types  are  emacs (this is the default), posix-awk, posix-basic, 
          posix-egrep and posix-extended.

I guess the emacs type doesn't support the [[:digit:]] construct. I tried it with posix-extended and it worked as expected:

find -regextype posix-extended -regex '.*[1234567890]'
find -regextype posix-extended -regex '.*[[:digit:]]'

answered Apr 12, 2011 at 13:15

bmk

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1 Comment

Dijkstra Over a year ago

I thought it might be that, but I checked the emacs regex definitions and they appear to support [:digit:]. gnu.org/software/emacs/manual/html_node/elisp/…

dogbane · Accepted Answer · 2011-04-12 13:21:00Z

57

Regular expressions with character classes (e.g. [[:digit:]]) are not supported in the default regular expression syntax used by find. You need to specify a different regex type such as posix-extended in order to use them.

Take a look at GNU Find's Regular Expression documentation which shows you all the regex types and what they support.

answered Apr 12, 2011 at 13:21

dogbane

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2 Comments

Dijkstra Over a year ago

Thanks. That document is the one I should have been looking for. All I could find was gnu.org/software/emacs/manual/html_node/elisp/… - which seemed to suggest that character classes were supported in "emacs regex mode".

asoundmove Over a year ago

Also check Regular_expression#Character_classes - very helpful resource

yegor256 · Accepted Answer · 2015-11-01 20:23:21Z

30

Note that -regex depends on whole path.

 -regex pattern
              File name matches regular expression pattern.  
              This is a match on the whole path, not a search.

You don't actually have to use -regex for what you are doing.

find . -iname "*[0-9]"

edited Nov 1, 2015 at 20:23

yegor256

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answered Apr 12, 2011 at 13:18

kurumi

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1 Comment

Al.G. Over a year ago

The excplicit dot is unneeded here, too ;)

StKiller · Accepted Answer · 2011-04-12 13:16:36Z

1

Well, you may try this '.*[0-9]'

answered Apr 12, 2011 at 13:16

StKiller

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