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sed script - transform 1st matching line only

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# 1  
Old 03-05-2010
sed script - transform 1st matching line only
How do transform only the first line that matches my regex? I've tried q but it just quit my script in the middle.
# 2  
Old 03-05-2010
For transforming the line in sed,you can use substitute command.For changing the first line alone.You use the following command.

Code:
sed -r '1s/^[0-9]+$/Numerical Values/' <filename>

The above command will change the first line into numerical values if it contains the numbers in the first line.
# 3  
Old 03-05-2010
Generally the sed command's substitution with the given pattern will replace the first occurrence of the match unless we explicitly specified the g flag.
# 4  
Old 03-05-2010
Yeah thillai,in substitute command if we didn't specify global flag,then it will replace only the first occurrence.But,I don't know why you have given this answer here?Did you read the question?Otherwise,you're saying in my solution,we need to give g flag?
# 5  
Old 03-05-2010
Well, I think the original question asked was to be able to replace only the FIRST macth of the reg expression and not necessarily the first line, which means, it can be match anywhere in the file but replace only the first occurance only..Confirmations?
# 6  
Old 03-05-2010
Thanks for the responses guys!

Yes, my question is the 1st regex match anywhere in the file. Not the 1st line of the file. I'm trying to do something like this:

Code:
/regex/ {
              transform only the first matching line
}

do some other stuff

# 7  
Old 03-05-2010
Try this:

Code:
awk 'BEGIN{cnt=0}$0 ~ /regexpr/ && cnt == 0{gsub(/regexpr/,"ReplacementString");cnt++}1' filename


cheers,
Devaraj Takhellambam
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