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Old 12-20-2011, 07:53 PM   #1
sopier
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removing more than 1 commas with sed perl or awk


I have many of this pattern in my text:
Code:
Center, , , , , , , , , VLC
How can I transform it to like this?
Code:
Center, VLC
I already try this command:
Code:
sed "s/,//g"
But it will get rid of the commas...

Any suggestions?
 
Old 12-20-2011, 07:59 PM   #2
crts
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Try this instead:

sed -r 's/(, *)+/, /g'
 
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Old 12-20-2011, 08:11 PM   #3
sopier
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Thank you... it works... can you tell me, when I should use "-r" in sed?
 
Old 12-20-2011, 08:30 PM   #4
crts
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The -r option simplifies the use of extended RegEx. It spares you from having to escape characters like '+' when you want to use it as a quantifier.

Read more about the -r option in this post:
http://www.linuxquestions.org/questi...4/#post4491722
 
Old 12-20-2011, 09:17 PM   #5
Telengard
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Hmm ...

Code:
$ echo "Center, , , , , , , , , VLC" | sed 's/, \(, \)*/, /g'
Center, VLC
According to the GNU sed manual, postfixed group expressions are required by POSIX but not portable. Weird. I guess that means the above solution might not work in non-GNU implementations of sed.

Probably best to stick with crts' ERE version. I don't see the need for the repetition operator in (, *) though ???

This should be portable to the best of my knowledge.

Code:
$ echo "Center, , , , , , , , , VLC" | awk '{gsub(/(, )+/, ", "); print}'
Center, VLC
 
Old 12-20-2011, 10:36 PM   #6
crts
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Quote:
Originally Posted by Telengard View Post
I don't see the need for the repetition operator in (, *) though ???
You are correct, it is just a precaution. I was not sure if the commas would always be separated by exactly one space. Even more precautious:
Code:
sed -r 's/(,[[:blank:]]*)+/, /g'
Now they can also be separated by tabs.
 
Old 12-21-2011, 12:11 AM   #7
Telengard
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Quote:
Originally Posted by crts View Post
Code:
sed -r 's/(,[[:blank:]]*)+/, /g'
Now they can also be separated by tabs.
Very well reasoned
 
  


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