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grep using regexp

 
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# 15  
Old 06-27-2007
Quote:
Originally Posted by Shell_Life
Code:
ls -al stu* | grep "stuff.*filter"

You always come through Shell Life... thanks.

and thanks for the explanation DRL... very insightful.

How does the dot make it differ from stuff-[ei]*-filter? Isn't the [ei] acting as a regular expression?
# 16  
Old 06-27-2007
Earnstaf,
The '*' in a file expression means anything,
in a regular expression means zero or more instances of previous character.
Thus:
Code:
>ls abc*def
abc-def    abcdef     abcXdef    abcXYZdef

Code:
>ls abc*def | grep "abc*def"
abcdef

Code:
>ls abc*def | grep "abc.*def"
abc-def
abcdef
abcXdef
abcXYZdef

# 17  
Old 06-27-2007
Hi.

This can be a confusing area, but once you master the difference, you are on your way to be able to use a wide variety of utilities in very efficient ways.

See the first part of http://en.wikipedia.org/wiki/Regular_expression for some explanatory material and references... cheers, drl
# 18  
Old 06-27-2007
Crystal clear...

thank you.
# 19  
Old 06-27-2007
Quote:
Originally Posted by drl
Hi.

This can be a confusing area, but once you master the difference, you are on your way to be able to use a wide variety of utilities in very efficient ways.

See the first part of http://en.wikipedia.org/wiki/Regular_expression for some explanatory material and references... cheers, drl
Agreed that it is a bit confusing. Even after reading the explanations it took a second for it to click... but I got it now.

Thanks to everyone for their help... this forum has been far and away the best tool I've found while learning the ins and outs of unix.
 
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