Control recording of data with the signal named signal. Whenever the signal is delivered to the process, it switches between the paused state, in which no data is recorded, and the recording state, in which data is recorded. Sample points are always recorded, regardless of the state of the switch.
The signal can be specified by the full signal name, by the signal name without the initial letters SIG, or by the signal number. Do not use a signal that is used by the program or that would terminate execution. Suggested signals are SIGUSR1 and SIGUSR2. Signals can be delivered to a process by the kill(1) command.
If you use both the -l and the -y options, you must use different signals for each option.
When the -y option is used, the Collector is started in the recording state if the optional r argument is given, otherwise it is started in the paused state. If the -y option is not used, the Collector is started in the recording state.
If you use this option and your program has its own signal handler, make sure that the signal that you specify with -y is passed on to the Collector’s signal handler, and is not intercepted or ignored.
See the signal(3HEAD) man page for more information about signals.