Print the first to sixth fields (separated by colons) of the file /etc/passwd, sort them by the fourth field (also separated by colons) numerically, and then print the first field of any line where the fourth field is greater than or equal to 1000.
cut -d: -f1-6 /etc/passwd | sort -t: -k4 -n | awk -F: '$4 >= 1000 {print $1}'