A.awk’{print$1}’/var/log/httpd/access_log∣sort
B.awk’{print$1}’/var/log/httpd/access_log∣sort∣uniq
C.awk’{print$1}’/var/log/httpd/access_log∣sort∣uniq∣wc-l
D.awk’{print$1}’/var/log/httpd/access_log

A.awk’{print$1}’access_log
B.sed’{print$1}’access_log
C.grep’{print$1}’access_log
D.cat’{print$1}’access_log