Watchpoints W <expression> - Set a watchpoint possibly better described as "Watch Expression" debugger will monitor value of expression if the value changes, the debugger returns control to the user. DB<1> W $buggyValue DB<2> c Watchpoint 0: $buggyValue changed: old value: '1982' new value: '1983' main::(port-scanner.pl:6): for($x=1;$x<2500;$x++) { to delete all watchpoints, specify no parameter Performance penalty - so only watch a few at a time setting a watchpoint: Perl <5.8:.... W <expression> Perl 5.8:..... w <expression> deleting a watchpoint: Perl <5.8:.... W Perl 5.8:..... W <expression>