note rjt <c>while (<DATA>) { s/ (?=.*\s?-1 )/,/g; print; } __DATA__ 01 fines name 2222 -P sws -1 reee.tee rrt 02 fi si 2232 -P sqww -1 re.wqw ttf 02 fi si-1 2232 -P sqww -1 re.wqw ttf</c> <p>This will replace spaces with commas before the last -1 in the file.</p> 1006740 1006740