uv_signal_t — Signal handle

Signal handles implement Unix style signal handling on a per-event loop bases.

Reception of some signals is emulated on Windows:

  • SIGINT is normally delivered when the user presses CTRL+C. However, like on Unix, it is not generated when terminal raw mode is enabled.
  • SIGBREAK is delivered when the user pressed CTRL + BREAK.
  • SIGHUP is generated when the user closes the console window. On SIGHUP the program is given approximately 10 seconds to perform cleanup. After that Windows will unconditionally terminate it.
  • Watchers for other signals can be successfully created, but these signals are never received. These signals are: SIGILL, SIGABRT, SIGFPE, SIGSEGV, SIGTERM and SIGKILL.
  • Calls to raise() or abort() to programmatically raise a signal are not detected by libuv; these will not trigger a signal watcher.


On Linux SIGRT0 and SIGRT1 (signals 32 and 33) are used by the NPTL pthreads library to manage threads. Installing watchers for those signals will lead to unpredictable behavior and is strongly discouraged. Future versions of libuv may simply reject them.

Changed in version 1.15.0: SIGWINCH support on Windows was improved.

Data types


Signal handle type.

void (*uv_signal_cb)(uv_signal_t* handle, int signum)

Type definition for callback passed to uv_signal_start().

Public members

int uv_signal_t.signum

Signal being monitored by this handle. Readonly.

See also

The uv_handle_t members also apply.


int uv_signal_init(uv_loop_t* loop, uv_signal_t* signal)

Initialize the handle.

int uv_signal_start(uv_signal_t* signal, uv_signal_cb cb, int signum)

Start the handle with the given callback, watching for the given signal.

int uv_signal_start_oneshot(uv_signal_t* signal, uv_signal_cb cb, int signum)

New in version 1.12.0.

Same functionality as uv_signal_start() but the signal handler is reset the moment the signal is received.

int uv_signal_stop(uv_signal_t* signal)

Stop the handle, the callback will no longer be called.

See also

The uv_handle_t API functions also apply.