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Replace nth position character of all the lines in file

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Homework and Emergencies Emergency UNIX and Linux Support Replace nth position character of all the lines in file
# 1  
Old 07-24-2012
Replace nth position character of all the lines in file
I want to replace 150th character of all the lines in a file using sed or awk...
searched the forums but didn't find exact answer
# 2  
Old 07-24-2012
replace the 150th character as X
Code:
awk '$0=substr($0,1,149)"X"substr($0,151,length($0))' input.txt > output.txt

---------- Post updated at 12:10 PM ---------- Previous update was at 12:07 PM ----------

if you have the lines with less than 150 characters, and dont want to append the X in the end, then use the below

Code:
 
awk 'length($0)>150{$0=substr($0,1,149)"X"substr($0,151,length($0))}1' input.txt

use nawk in solaris
# 3  
Old 07-24-2012
With sed:
Code:
sed 's/^\(.\{149\}\)./\1X/' inputfile

This User Gave Thanks to elixir_sinari For This Post:
greenworld123
# 4  
Old 07-26-2012
Shorter:
Code:
sed 's/./X/149' input

# 5  
Old 07-26-2012
Quote:
Originally Posted by balajesuri
Shorter:
Code:
sed 's/./X/149' input

To replace the 150th character, that should be 150, not 149.

Regards,
Alister
# 6  
Old 07-26-2012
Ah, my bad. You're right alister.
# 7  
Old 08-01-2012
On the same lines how do I replace nth column in the file ?

for example

Code:
assgin  crclk  unit1 unit2
assign tap  signal_a

Want to put = after 2nd column

Code:
assign crclk = unit1 unit2
assgin tap = signal_a

Last edited by methyl; 08-01-2012 at 07:09 PM.. Reason: Please use code tags. Space characters are so important when editing.
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