regex and grep


 
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# 1  
Old 05-17-2009
regex and grep

I want it to find lines that contain any number of capital letters before P

this is what I have tried
Code:
echo "AAAAAP" | grep '[A-Z]P'
echo "AAAAAP" | grep '[A-Z]\{1\}P'
echo "AAAAAP" | grep '^[A-Z]*P'

But none of them seem to work, any help is much appreciated

thanks
Calypso
# 2  
Old 05-17-2009
Do the capital letters have to begin at the start of the line? IF yes --
Code:
echo "AAAAAP" | egrep '^[A-Z]+P'

# 3  
Old 05-18-2009
Thanks a lot!, works a charm

Last edited by Calypso; 05-18-2009 at 08:04 AM..
# 4  
Old 05-18-2009
please could you just explain why it only works with egrep and not the normal grep

also please could just confirm the following

^ means must start with pattern
+ means one or more occurence of pattern

Thanks again

Calypso
# 5  
Old 05-18-2009
Quote:
Originally Posted by Calypso
... why it only works with egrep and not the normal grep
...
That's because of that pesky "+" character, which means "one or more occurrence" and is an extended regex and hence supported by egrep (extended grep). Check the man page for egrep in your system.

The equivalent regex for this in grep would be:

Code:
$
$ echo "AAAAAP" | grep '^[A-Z][A-Z]*P'
AAAAAP
$

tyler_durden
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