substitute a string on a specific position for specific lines
I woud like to substitue a string on a specific position for specific lines
I've got a file and I would like to change a specific string from "TOCHANGE" to "ABCABCAB"
For every line (except 1,2, 3 and the last one) , I need to check between the 9th and the 16th digits.
For the 3rd line, I need to check between the 12th and the 19th digits.
No checks for line 1,3 and the last one.
------------------------
------------------------
example 1:
Code:
line 3
12345678901TOCHANGE12345
Line 25,....
12345678TOCHANGE12345678
123456789TOCHANGE1234567
TOCHANGE1234567890123456
Only the line 3 and 25 need to be amended
So I would like to get
Code:
line 3
12345678901ABCABCAB12345
Line 25,...
12345678ABCABCAB12345678
123456789TOCHANGE1234567
TOCHANGE1234567890123456
-------------------------
-------------------------
example 2:
Code:
line 3
123456789TOCHANGE1234567
Line 25,....
12345678TOCHANGE12345678
123456789TOCHANGE1234567
TOCHANGE1234567890123456
Only the line 25 needs to be amended
So I would like to get
Code:
Line 3
123456789TOCHANGE1234567
Line 25,...
12345678ABCABCAB12345678
123456789TOCHANGE1234567
TOCHANGE1234567890123456
Do you have any idea about how I could do it?
I tried with the sed command but it works on the number of occurence.
I think it could be done via the awk command
Many thanks
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Last edited by Franklin52; 12-29-2010 at 09:19 AM..
I'm editing my post because I just re-read your post and saw that you are only looking at specific locations on each line. Also, I see that you already tried sed. I believe awk will accept a period for a single character. You could try using a while loop to read each line (while line=$(line)) and checking for a successful status on an awk command like: awk '/^........TOCHANGE/' $line. If that is successful, you could then use a sed (newline = `sed -e 's/TOCHANGE/ABCABCAB' $line`).
My apologies for the confusion, but I hope it helps. By the way, I didn't have a file like this to try. So, these are untried suggestions.
Last edited by ducet8; 12-13-2010 at 01:31 PM..
Reason: wrong information
Thanks for this.
But I was wondering whether or not it could be possible to do it without a loop.
I'd like to use an 'awk' or a 'sed'.
My first thought was to use a sed but it works by occurence.
@ctsgnb
Good way to get 2nd last line no but I guess above script needs to be modified as below:
Ignore line 1,2 and the last one (No change)
For the 3rd line, Replace only if TOCHANGE is in 12th to 19th position.
For other lines (4th - 2nd last), Replace only if TOCHANGE is in 9th to 16th position.
Ooops, you are true, i totally forgot that position case ... here is an even better
- need caret ^ to be exact regarding the position otherwise the \(.....<n_times>\)TOCHANGE could also be match at a position greater than the expected one
- use the $! tip to avoid last line)
- therefore avoid the use of additionnal file opening & line counting of the wc -l
- no need of sed -e option
Code:
sed '3s/^\(...........\)TOCHANGE\(.*\)/\1ABCABCAB\2/;$!{4,$s/^\(........\)TOCHANGE\(.*\)/\1ABCABCAB\2/}' infile
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12-13-2010
