如果输出顺序无关紧要，则可以采用一种方法:

If the output order doesn't matter, here's a one-pass approach:

$ awk -F';' '$3 in first{print first[$3] $0; first[$3]=""; next} {first[$3]=$0 ORS}' file
Mike;Tyson;mike@tyson.com
Tom;Cruise;mike@tyson.com
Mike;Myers;mike@tyson.com
Tom;Boyden;tom@boyden.com
Andre;Agassi;tom@boyden.com