grep : regular expression


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# 1  
Question grep : regular expression

guys,

my requirment goes like this:

I have a file, and wish to filter out records where

1. The first letter is o or O
and
2. The next 4 following letter should not be ther

I do not wish to use pipe and wish to do it in one shot.
The best expression I came up with is:

grep ^[oO][^tT][^hH][^eE][^rR]* test1

But with this there is a problem if the word is beginning with o and less then 4 letters it excludes those.

Thanks in advance to the R.E gurus Smilie

rishi
# 2  
Did you try

Code:
grep -v -i 'other' test1

vino
# 3  
Tools

Thanks Vino for suggestion, but this will not satisfy my requirment:

say my file has

one
only
fine
other
clear
output
o

the result of search should be
one
only
output
o

suppose if i go the way you suggest it will also include "clear" i.e the word not beginning with "o"

hope this sample clarifies the question

rishi
# 4  
So your list will only contain words and not lines/sentences ?
# 5  
Quote:
Originally Posted by vino
So your list will only contain words and not lines/sentences ?

Can be both ways Smilie
# 6  
grep -v -i 'other' test1 | grep '^[oO]'

If running 2 greps is acceptable
# 7  
Code:
[~/temp]$ cat rishi.txt 
one 
only 
fine
other 
clear
output
o

Code:
[~/temp]$ sed -n -e '/[oO][tT][hH][eE][rR]/d' -e '/[oO]/p' rishi.txt 
one 
only 
output
o

Will print lines having an o or O.
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