I have tried this shell script on a SUSE 10 server, kernel 2.6.16.60, ext3 filesystem the script has problem like this: cat file | awk '{print $1" "$2" "$3}' | sort -n > result the file's size is about 3.2G, and I get such error message: File size limit exceeded in this shell, ulimit -f is unlimited after I change script into this cat file | awk '{print $1" "$2" "$3}' >tmp sort -n tmp > result the problem is gone. I don't know why, can anyone help me with an explanation?