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Full Discussion: | help | unix | grep (GNU grep) 2.5.1 | advanced regex syntax
Top Forums UNIX for Dummies Questions & Answers | help | unix | grep (GNU grep) 2.5.1 | advanced regex syntax Post 302362244 by MykC on Thursday 15th of October 2009 10:52:33 AM
Old 10-15-2009
Ok, cool. You gave me some insight. For reference, the below line returns lines with exactly 3 matches if 'x' in the entire line.
3 can be replaced with any positive integer.
'x' can be replaced by any string.

Code:
grep "^\([^x]*x\)\{3\}[^x]*$" /usr/share/dict/words
grep -E "^([^x]*x){3}[^x]*$" /usr/share/dict/words

Addinging the option -E allowed to removed the "\" for the special characters and the code worked as expected.
There is also -P option for Perl extensions.

Code:
grep -E "^(?:[^x]*x){3}[^x]*$" /usr/share/dict/words
grep -P "^(?:[^x]*x){3}[^x]*$" /usr/share/dict/words

-E returned nothing when I added the ?: to ()
-P returned everything

I'm getting closer, I'll just need sometime to fool around with it. Thanks for the help.

Regular Expression Reference - Advanced Syntax
UNIX man pages : grep ()
 

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LEARN ABOUT DEBIAN

canadian-english

canadian-english(5)						   Users' Manual					       canadian-english(5)

NAME

       canadian-english - a list of English words

DESCRIPTION

       /usr/share/dict/canadian-english is an ASCII file which contains an alphabetic list of words, one per line.

FILES

       There  may  be  any  number  of	word lists in /usr/share/dict/.  /etc/dictionaries-common/words is a symbolic link to the currently-chosen
       /usr/share/dict/<language> file.  /usr/share/dict/words is a symbolic link to /etc/dictionaries-common/words, and  is  the  name  by  which
       other  software should refer to the system word list.  See select-default-wordlist(8) for more information, and/or to change the currently-
       chosen word list.

       The directory /usr/share/dict can contain word lists for many languages, with name of the language in English, e.g., /usr/share/dict/french
       and  /usr/share/dict/danish  contain respectively lists of French and Danish words if they exist.  Such lists should be coded using the ISO
       8859-1 character set encoding.

SEE ALSO

       ispell(1), select-default-wordlist(8), and the Filesystem Hierarchy Standard.

HISTORY

       The words lists are not specific, and may be generated from any number of sources.

       The system word list used to be /usr/dict/words.  For compatibility, software should check that location if /usr/share/dict/words does  not
       exist.

AUTHOR

       Word  lists  are  collected and maintained by various authors.  The Debian English word lists are built from the SCOWL (Spell- Checker Ori-
       ented Word Lists) package, whose upstream editor is Kevin Atkinson <kevina@users.sourceforge.net>.

Debian								   16 June 2003 					       canadian-english(5)
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