Shell Programming and Scripting

Hi, so thanks for the input everyone. To clarify, in my input file the 0 is just an example of the data I want to replace, this can be text or other numbers or a combination of both. I have a loop running to replace everything so basically I will have $var which is the string to look for and $replace which is the replacement for it. Since it's in a loop the values of each variable will be changed with a new iteration. The issue I had in my script originally was that I was using sed and that replaced later values of $var when it shouldn't be so I wanted to limit it to just the first instance since my script will read the file top to bottom.

In any case, it sounds like sed isn't the best method. I tried the awk from above replacing what I thought to be my variables but no luck. I tried the following:

awk 'c && /^$var$/{$0=r;c--}1' c=1 r="$replace" file > newfile

Code:

awk 'c && /$0==s/{$0=r;c--}1' c=1 r="$replace" s="$var" file > newfile

Regards

looks like job for ksh:

Code:

my_serial=123

cat file |
while read junk ; do

  if [ $junk -eq 0 ]; then
    my_serial=$(( my_serial + 1 ))
    echo $my_serial
    continue
  fi

  echo $junk

done