### 13.3 Convenience Variables for Tracepoints

`(int) $trace_frame`
  The current trace snapshot (a.k.a. frame) number, or -1 if no snapshot is selected.

`(int) $tracepoint`
  The tracepoint for the current trace snapshot.

`(int) $trace_line`
  The line number for the current trace snapshot.

`(char []) $trace_file`
  The source file for the current trace snapshot.

`(char []) $trace_func`
  The name of the function containing `$tracepoint`.

Note: `$trace_file` is not suitable for use in `printf`, use `output` instead.

Here's a simple example of using these convenience variables for stepping through all the trace snapshots and printing some of their data.

         (gdb) tfind start

         (gdb) while $trace_frame != -1
         > output $trace_file
         > printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint
         > tfind
         > end