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Help with grep?

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Join Date: Nov 2009

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Mattpd

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Help with grep?

23 Days Ago

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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Join Date: Feb 2006

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masijade

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23 Days Ago

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

Java Programmer and Sun Systems Administrator

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Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
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Join Date: Dec 2006

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Aia

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Postaholic

23 Days Ago

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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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23 Days Ago

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)