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ogronom

Member

From: Toronto, Canada

Registered: 2008-05-06

Posts: 123

[SOLVED]sed: regex repeated pattern

Hi all,

Currently I'm struggling with bash script for automatic presorting and converting of photos from camera.
While man page says that {} is repeated of previous pattern it does not work for me. Here is the example (basically I want extract year of the timestamp).

% exiv2 20080930--DCIM/100CANON/IMG_0002.JPG| grep timestamp
Image timestamp : 2008:05:09 10:25:02
% exiv2 20080930--DCIM/100CANON/IMG_0002.JPG| grep timestamp | sed 's@.*\([0-9]{4}\).*@\1@'
Image timestamp : 2008:05:09 10:25:02
% exiv2 20080930--DCIM/100CANON/IMG_0002.JPG| grep timestamp | sed 's@.*\([0-9]{3}\).*@\1@'
Image timestamp : 2008:05:09 10:25:02

And this one works

% exiv2 20080930--DCIM/100CANON/IMG_0002.JPG| grep timestamp | sed 's@.*\([0-9][0-9][0-9][0-9]\).*@\1@'
2008

If I need repeated m times this is not acceptable. How to deal with this?

Last edited by ogronom (2010-04-05 16:26:54)

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: [SOLVED]sed: regex repeated pattern

' exiv2 20080930--DCIM/100CANON/IMG_0002.JPG| grep timestamp | cut -c 19-22' might do as well.

ogronom

Member

From: Toronto, Canada

Registered: 2008-05-06

Posts: 123

Re: [SOLVED]sed: regex repeated pattern

I'm not interested in workarounds (there is one posted above). I'm wondering why  {} does not work. Most porobable my understanding of the man re_syntax is incorrect, I just wonder why.

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: [SOLVED]sed: regex repeated pattern

Escaping '{' and '}' helps:

sed 's@.*\([0-9]\{4\}\).*@\1@'

Last edited by karol (2010-04-05 16:24:22)

ogronom

Member

From: Toronto, Canada

Registered: 2008-05-06

Posts: 123

Re: [SOLVED]sed: regex repeated pattern

Found
Silly issue. instead of {} one should use \{\}

ogronom

Member

From: Toronto, Canada

Registered: 2008-05-06

Posts: 123

Re: [SOLVED]sed: regex repeated pattern

Thanks, karol