A.cat file〡cut-d“-”-f3 B.cat files〡ed‘3p’ C.cat file〡grep‘3’ D.cat file〡awk-F“-”‘{print$3}’
A.sed-n’/^r/p’/etc/passwd B.grep’^r’/etc/passwd C.grep’[^r]’/etc/passwd D.awk’/^r/{print$0}’/etc/passwd