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search for string and replace backwards


 
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# 1  
Old 10-10-2009
search for string and replace backwards

I'm new to Unix scripting and I'm not sure if this can be done. Example:

search (grep) in a file for 'Control ID' and then replace with 4 blanks 7 bytes before 'Control ID.

input
"xxxxxx1234xxxxxxxControl IDxxxxxx"

output:
"xxxxxx xxxxxxxControl IDxxxxxx"

thanks!
# 2  
Old 10-10-2009
Hi.

Using sed:

Code:
sed "s/\(.*\)....\(.\{7\}Control ID.*\)/\1 \2/" input_file
 
xxxxxx xxxxxxxControl IDxxxxxx

# 3  
Old 10-10-2009
thanks a lot..
# 4  
Old 10-12-2009
This works, but replaces with 1 space not 4 spaces

Scott,

the command works ok, but 1 space replaces 4 bytes which compresses the file:

sed "s/\(.*\)....\(.\{7\}Control ID.*\)/\1 \2/"

In:
abcde****1234567Control ID890

to:
abcde 1234567Control ID890

need:
abcdebbbb1234567Control ID890

with b= space

Thanks!
# 5  
Old 10-12-2009
Hi.

Add some spaces between \1 and \2

Code:
sed "s/\(.*\)....\(.\{7\}Control ID.*\)/\1    \2/" file2
xxxxxx    xxxxxxxControl IDxxxxxx

# 6  
Old 10-12-2009
Thanks Scott! that worked..

---------- Post updated at 11:12 AM ---------- Previous update was at 09:26 AM ----------

when I try to run this on my production file it does not work. I think it's the file size or record length issue. Does sed have a limit for record lenght? should I try awk instead?
# 7  
Old 10-12-2009
Hi.

No, it doesn't.

I just ran it on a file with a record (line) length of 750,000, and it worked fine.

Please state what the problem is (error message, etc.), and show what you did.

Thanks.

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