find and -regex

Business_Woman · #1 September 19th, 2011, 20:07

Hi,

This question is purely academic.

A simple

Code:

ls /bin | egrep '^..$'

gives a nice list of all the binaries that are two characters long, mv cp ls etc..

But for some reason this doesn't work

Code:

 find -E /bin -regex '^..$'

Why?

respite · #2 September 19th, 2011, 21:15

Not entirely sure as I never use find regex's, though ls will output only the filename while find will produce the full path.

kpa · #3 September 19th, 2011, 21:16

You're matching the whole string with -regex so you have to account for the /bin/ at the beginning.

Code:

 find -E /bin -regex '.*/..$'

Business_Woman · #4 September 19th, 2011, 21:20

Thank you.

**wblock@** · #5 September 19th, 2011, 21:24

find(1):

Code:

    -regex pattern
             True if the whole path of the file matches pattern using regular
             expression.  To match a file named “./foo/xyzzy”, you can use the
             regular expression “.*/[xyz]*” or “.*/foo/.*”, but not “xyzzy” or
             “/foo/”.

Let's see what the input to that regex really is:

Code:

% find -E /bin -print
/bin
/bin/cat
/bin/chflags
/bin/chmod
/bin/cp
/bin/chio
...

Aha. find returns the whole path. My use of find(1) is mostly by rote; if there's a way to get it to return basenames only, then it would work.

Business_Woman · #6 September 19th, 2011, 21:40

yes, sorry. I should have read the man page more careful >_>

If i want to match all binaries in /bin that are three characters long and starts with 'p'.

Code:

find -E /bin -regex '\( .*/.. -and -regex '.*\^p \)'

Hm?

**wblock@** · #7 September 20th, 2011, 06:03

Easier to do in a single regex:
% find /bin -regex '.*/p..$'

But for this use, ls and grep are more appropriate, shorter and simpler.
% ls /bin | grep '^p..$'

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The Following User Says Thank You to kpa For This Useful Post:
Business_Woman (September 19th, 2011)