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Grep issue

 
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# 1  
Old 07-28-2011
Question Grep issue
Code:
more Hello.txt

it was a sunny way and i was about to go home.

I need to grep and redirect to a new file all the text between 'sunny' and 'go' string above.

Note: There may be multiple lines in between the string i need to grep between. If there are multiple 'go' strings it should grep till the last 'go' string is found in the text file.

Can you please quick help ?

Regards,
Mohtashim
Last edited by pludi; 07-28-2011 at 12:38 PM..
# 2  
Old 07-28-2011
What is your system? What is your shell?
# 3  
Old 07-28-2011
You can't do it with grep. With perl it's easy. And this should work on all *nixes:
Code:
sep=`echo : | tr : '\01'`
cat INPUTFILE | tr '\n' $sep  | sed 's/^.*\(sunny.*go\).*$/\1/' | tr $sep '\n'

If there are several "sunny.*go" in the file then only the last would match.
# 4  
Old 07-28-2011
Useless Use of Cat
# 5  
Old 07-28-2011
Useful use of cat(1)
"easy "intuitive" switching on the command line between different types input"
# 6  
Old 07-28-2011
"The fact that the same thread ("but but but, I think it's cleaner / nicer / not that much of a waste / my privelege to waste processes!") springs up virtually every time the Award is posted is also Ancient Usenet Tradition." -- uuoc

You can get the same ordering without it anyway:

Code:
<filename program ...

So it's a bad habit with zero benefits.
# 7  
Old 07-28-2011
From Bash cookbook:

Useless Use of cat
Certain Unix users take a positively giddy delight in pointing out inefficiencies in
other people's code. Most of the time this is constructive criticism gently given and
gratefully received.
Probably the most common case is the so-called “useless use of cat award” bestowed
when someone does something like cat file | grep foo instead of simply grep foo
file. In this case, cat is unnecessary and incurs some system overhead since it runs in
a subshell. Another common case would be cat file | tr '[A-Z]' '[a-z]' instead of
tr '[A-Z]' '[a-z]' < file. Sometimes using cat can even cause your script to fail (see
Recipe 19.8, “Forgetting That Pipelines Make Subshells”).
But... (you knew that was coming, didn't you?) sometimes unnecessarily using cat
actually does serve a purpose. It might be a placeholder to demonstrate the fragment
of a pipeline, with other commands later replacing it (perhaps even cat -n). Or it
might be that placing the file near the left side of the code draws the eye to it more
clearly than hiding it behind a < on the far right side of the page.
While we applaud efficiency and agree it is a goal to strive for, it isn't as critical as it
once was. We are not advocating carelessness and code-bloat, we're just saying that
processors aren't getting any slower any time soon. So if you like cat, use it.

The good book, btw.
 
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