Shell Scripting

Help with grep?

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Join Date: Nov 2009

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Mattpd

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Help with grep?

Nov 11th, 2009

If I have two lines of text:

HOOK
HOOK HOOK

what is the syntax to grep just the first line without the second? and the second without the first?

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masijade

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Nov 11th, 2009

http://www.regular-expressions.info/tutorial.html

Java Programmer and Sun Systems Administrator

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Aia

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Nov 11th, 2009

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Originally Posted by Mattpd

If I have two lines of text:

HOOK
HOOK HOOK

what is the syntax to grep just the first line without the second? and the second without the first?

Find any difference between both and then match it. e.g. with HOOK by itself in a line we can match the beginning and end of the line. Thus:

Help with Code Tags

Shell Scripting Syntax (Toggle Plain Text)

grep '^HOOK$' file_name

Once you have down the successful match the opposite will work in this case, using the -v switch.

Help with Code Tags

Shell Scripting Syntax (Toggle Plain Text)

grep -v '^HOOK$' file_name

Will match HOOK HOOK
However, if there were another line containing something that is not ^HOOK$ it will produce a match as well.

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Join Date: Oct 2009

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Xydric

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Nov 11th, 2009

Are you wanting to try and grep "HOOK" on a line by itself, or specifically just the first match?

There are all sorts of things that you could actually want to know, although I am not sure which you are wanting. What exactly is it that you are needing to do?

 Help with Code Tags 
 Shell Scripting Syntax (Toggle Plain Text) 
# grep a file, return first result and stop
grep -m1 "HOOK" file.txt
 
# grep a file, only return result with HOOK on line by itself
grep -P "^HOOK$" file.txt
# you can also use egrep (or instead of -P use pgrep)
# grep a file, return first result and stop
grep -m1 "HOOK" file.txt

# grep a file, only return result with HOOK on line by itself
grep -P "^HOOK$" file.txt
# you can also use egrep (or instead of -P use pgrep)