UNIX for Advanced & Expert Users

Sure,

Code:

awk 'substr($0,21,1)==9{print $1,substr($2,1,12)"1900"substr($2,17);next}1' file

substr($0,21,1)==9 -> if postition 21 of the line = 9 then do everything between the braces

print $1 -> print first field (before the space)

substr($2,1,12) -> print position 1 to 12 of second field (after space)

"1900"substr($2,17);next} -> print "1900" and position 17 of second field untill the end of the string and read the next line

1 -> print other lines

Go here for some tutorials:

https://www.unix.com/answers-frequent...tutorials.html


Regards

thanks so much

I had one last question on the above requirement. I tried a few changes in the awk code but did not work.


awk 'substr($0,21,1)==9{print $1,substr($2,1,12)"1900"substr($2,17);next}1' file

this will replace anything that has "9” in column 21 with ‘1900' in column 42.

what if i need to replace only records that has "9” in column 21 AND '1999' in column 42 ( matches both this criteria ) with ‘1900' in column 42.

Please advise

Thanks,
Sandeep

Code:

awk 'substr($0,21,1)==9 && substr($0,42,4)==1999{print $1,substr($2,1,12)"1900"substr($2,17);next}1' file

Regards

Thanks so much

Hi,

In my prevoius example file there was only one small space

example:

0011200ALN00000000009EGYPT 000000000000199900000

what If my file has spaces like the below file:

0011200ALN00000000009EGYPT 000000000000199900000
0011200ALN00000000009EGYPT 000000000000000000000
146920000100000000009DE SOTO 000000000001999000000

Can't there be a generic script written for this

Please advise?

Thanks,
Sandeep

Just operate on $0 all the time. $0 is the entire input line in awk, $1 $2 $3 etc is split into individual fields (on whitespace by default).

Code:

awk 'substr($0,21,1)==9 && substr($0,42,4)==1999{
  print substr($0,0,41) "1900" substr($0, 46); next }
1'

The offsets in your latest example don't match what was posted before; do you have multiple adjacent spaces there? Please use code tags when posting material where spaces are significant.

The vi tip also works; you can use sed instead of vi, although the regular expressions would be getting rather clumsy.