gdb: Signaling
17.3 Giving your Program a Signal
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'signal SIGNAL'
Resume execution where your program is stopped, but immediately
give it the signal SIGNAL. The SIGNAL can be the name or the
number of a signal. For example, on many systems 'signal 2' and
'signal SIGINT' are both ways of sending an interrupt signal.
Alternatively, if SIGNAL is zero, continue execution without giving
a signal. This is useful when your program stopped on account of a
signal and would ordinarily see the signal when resumed with the
'continue' command; 'signal 0' causes it to resume without a
signal.
_Note:_ When resuming a multi-threaded program, SIGNAL is delivered
to the currently selected thread, not the thread that last reported
a stop. This includes the situation where a thread was stopped due
to a signal. So if you want to continue execution suppressing the
signal that stopped a thread, you should select that same thread
before issuing the 'signal 0' command. If you issue the 'signal 0'
command with another thread as the selected one, GDB detects that
and asks for confirmation.
Invoking the 'signal' command is not the same as invoking the
'kill' utility from the shell. Sending a signal with 'kill' causes
GDB to decide what to do with the signal depending on the signal
handling tables (
Signals). The 'signal' command passes the
signal directly to your program.
'signal' does not repeat when you press <RET> a second time after
executing the command.
'queue-signal SIGNAL'
Queue SIGNAL to be delivered immediately to the current thread when
execution of the thread resumes. The SIGNAL can be the name or the
number of a signal. For example, on many systems 'signal 2' and
'signal SIGINT' are both ways of sending an interrupt signal. The
handling of the signal must be set to pass the signal to the
program, otherwise GDB will report an error. You can control the
handling of signals from GDB with the 'handle' command (
Signals).
Alternatively, if SIGNAL is zero, any currently queued signal for
the current thread is discarded and when execution resumes no
signal will be delivered. This is useful when your program stopped
on account of a signal and would ordinarily see the signal when
resumed with the 'continue' command.
This command differs from the 'signal' command in that the signal
is just queued, execution is not resumed. And 'queue-signal'
cannot be used to pass a signal whose handling state has been set
to 'nopass' (Signals).
stepping into signal handlers, for information on how
stepping commands behave when the thread has a signal queued.
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