Find and replace a string a specific value in specific location in AIX

techmoris · #1 03-11-2010

Hi,

I have following samp.txt file in unix.

samp.txt

01Roy2D3M000000
02Rad2D3M222222
.
.
.
.
10Mik0A2M343443

Desired Output

01Roy2A3M000000
02Rad2A3M222222
.
.
.
.
10Mik0A2M343443

I want to find a value for 2D3M in the 6,7,8,9 positions from the beginning of record, if found need to replace it with 2A3M

Thanks

anbu23 · #2 03-11-2010

Code:

sed "s/^\(.\{5\}\)2D3M/\12A3M/" file

techmoris · #3 03-11-2010

Hi anbu23,

Thanks for quick reply..so this will check for the string only in the 6, 7, 8, 9 positions only right..and it should not check any other positions of every records of the file..

sed "s/^\(.\{5\}\)2D3M/\12A3M/" file

what does 1 mean before 2A3M in the above SED command.

Pls respond..thanks..

anbu23 · #4 03-11-2010

sed code will check 2A3M only from 6th to 9th position in the file.

Quote:

Save the pattern enclosed between \( and \) in a special holding space. Up to nine subpatterns can be saved on a single pattern. The text matched by the subpatterns can be reused later in the same pattern, by the escape sequences \1 to \9. For example, \(ab\).*\1 matches two occurrences of ab, with any number of characters in between.

\(.\{5\}\) Holds first five characters. [COLOR="rgb(255, 0, 255)"]\1[/COLOR] gives the first five characters saved in [COLOR="rgb(255, 0, 255)"]\( \)[/COLOR]

techmoris · #5 03-11-2010

gr8..thanks/...it worked..)

rdcwayx · #6 03-11-2010

Sed is better in this case, here is the awk code.

Code:

awk -F "" '{if (substr($0,6,4)=="2D3M") $7="A"}1' OFS="" samp.txt

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