In dbx, most of the event management commands also support an optional event filter modifier. The simplest filter instructs dbx to test for a condition after the program arrives at a breakpoint or trace handler, or after a data change breakpoint occurs.
If this filter condition evaluates to true (non 0), the event command applies and program execution stops at the breakpoint. If the condition evaluates to false (0), dbx continues program execution as if the event had never happened.
To set a breakpoint that includes a filter , add an optional- if condition modifier statement to the end of a stop or trace command.
The condition can be any valid expression, including function calls, returning Boolean or integer in the language current at the time the command is entered.
With a location-based breakpoint like in or at, the scope for parsing the condition is that of the breakpoint location. Otherwise, the scope of the condition is the scope at the time of entry, not at the time of the event. You might have to use the backquote operator (see Backquote Operator) to specify the scope precisely.
The following two filters are not the same:
stop in foo -if a>5 stop cond a>5
The former breaks at foo and tests the condition. The latter automatically single steps and tests for the condition.