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Put a character before each line

 
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# 1  
Old 06-19-2013
Put a character before each line
i have few lines:
Code:
3 4 5 6
#72 9 9 9
4 5 67 8 9
#4 6 8 92 1

i want to put '#' before each line.
i used this
Code:
awk '{print "#" $0;}

it gave
Code:
#3 4 5 6
##72 9 9 9
#4 5 67 8 9
##4 6 8 92 1

but i want the output like this:
Code:
#3 4 5 6
#72 9 9 9
#4 5 67 8 9
#4 6 8 92 1

I want to avoid the character if it's present already. could you pls tell me the command?
Last edited by radoulov; 04-03-2014 at 12:22 PM..
# 2  
Old 06-19-2013
How about and edit that removes the leading # if it exists and then add a # to every line?

Does that suggest anything?



Robin
Liverpool/Blackburn
UK
# 3  
Old 06-19-2013
Code:
sed '/^#/ ! s/^/#/' /path/to/input

This s/^/#/ puts a "#" in front of a line. This: /^#/ ! makes sure this operation is only carried out on lines not starting with "#".

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
arindam guha
# 4  
Old 06-19-2013
A slightly different version:

Code:
sed 's/^[^#]/#&/' infile

Prefix every line that starts with a character different than # with #.
This User Gave Thanks to radoulov For This Post:
arindam guha
# 5  
Old 06-19-2013
Quote:
Originally Posted by radoulov
A slightly different version:

Code:
sed 's/^[^#]/#&/' infile

Prefix every line that starts with a character different than # with #.
Code:
awk ' { sub("^[^#]","#&") } 1 '  file

This User Gave Thanks to anbu23 For This Post:
arindam guha
# 6  
Old 06-19-2013
Thanks all of u.....got the desired output
 
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