The Perl Debugger - Help for Breakpoints (h b)

  DB<1> h b
b        Sets breakpoint on current line)
b [line] [condition]
        Set breakpoint; line defaults to the current execution line;
        condition breaks if it evaluates to true, defaults to '1'.
b subname [condition]
        Set breakpoint at first line of subroutine.
b $var        Set breakpoint at first line of subroutine referenced by $var.
b load filename Set breakpoint on 'require'ing the given file.
b postpone subname [condition]
        Set breakpoint at first line of subroutine after
        it is compiled.
b compile subname
        Stop after the subroutine is compiled.