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Old 09-16-2013, 02:43 PM   #1
shusai
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Registered: May 2011
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sed: remove lines from a text file not containing parentheses


I want to delete lines from a text file which do not contain parentheses, e.g.:

This is the first line.
This is (123) another line.
Another line.
One more (useless) line.

The result should be:

This is (123) another line.
One more (useless) line.

I found out that
Code:
sed '/(/!d' file > output
should do what I want, but it gives me an empty file.

How can I delete lines NOT containing parentheses?
Thank you for your help!
 
Old 09-16-2013, 03:20 PM   #2
suicidaleggroll
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Personally, I would just grep for parenthesis and toss it into a new file. Something like

Code:
grep "(" file > newfile
Unless there's some reason this wouldn't work for you.
 
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Old 09-16-2013, 03:29 PM   #3
kabamaru
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There are many ways you can do this. The thing is, your command _should_ work (works fine here). Do you by any chance use the same file as input, as well as output? If that's the case, yes your file's contents will just get erased. So, either you choose an output file other than the input file, or edit the original file in place (generally unsafe) with:

Code:
sed -i '/(/!d' file

Last edited by kabamaru; 09-16-2013 at 03:30 PM.
 
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Old 09-16-2013, 10:36 PM   #4
jpollard
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Quote:
Originally Posted by shusai View Post
I want to delete lines from a text file which do not contain parentheses, e.g.:

This is the first line.
This is (123) another line.
Another line.
One more (useless) line.

The result should be:

This is (123) another line.
One more (useless) line.

I found out that
Code:
sed '/(/!d' file > output
should do what I want, but it gives me an empty file.

How can I delete lines NOT containing parentheses?
Thank you for your help!
Try "grep '(' file >output". No real need for sed.
 
1 members found this post helpful.
Old 09-17-2013, 11:04 AM   #5
shusai
LQ Newbie
 
Registered: May 2011
Posts: 2

Original Poster
Rep: Reputation: 0
Thank you all for your help, both the grep and sed with -i work!
 
  


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