If a file in unix has the string "123ABC" in it on 50 different lines and I only want to replace the first 25 of them with "xxxxxx", how would I do that with a unix command?? Thanks for any help or info you can provide... Hubb

Try the following script : #!/usr/bin/awk -f # subn str= by= count= input_file # str = string to be replace # by = replacement string # count = max replacement count # {    if (count == "")       gsub(str, by);    else {       while (count>0) {          if (sub(str, by))             count--;          else             break;       }    }    print; } subn str="123ABC" by="xxxxxx" count=25 input_file Jean-Pierre.

I didn't test it, but this should work. from the command line: perl -pi -e 'if(s/123ABC/xxxxxx/){$i++; last if($i==25)}' input_file

I think it will also work if we condense it a little more, like this: perl -pi -e 'if(s/123ABC/xxxxxx/){last if ($i++==25)}' input_file