Module posix.signal

Software Signal Facilities.

Constants and functions for propagating signals among processes.

Note that posix.signal.signal is implemented with sigaction(2) for consistent semantics across platforms. Also note that installed signal handlers are not called immediatly upon occurrence of a signal. Instead, in order to keep the interperter state clean, they are executed in the context of a debug hook which is called as soon as the interpreter enters a new function, returns from the currently executing function, or after the execution of the current instruction has ended.

Functions

kill (pid, opt) Send a signal to the given process.
killpg (pgrp[, sig=`SIGTERM`]) Send a signal to the given process group.
raise (sig) Raise a signal on this process.
signal (signum[, handler=SIG_DFL[, flags]]) Install a signal handler for this signal number.

Constants

posix.signal Signal constants.


Functions

kill (pid, opt)
Send a signal to the given process.

Parameters:

  • pid int process to act on
  • opt int =SIGTERM sig signal to send

Returns:

    int 0, if successful

Or

  1. nil
  2. string error message
  3. int errnum

See also:

killpg (pgrp[, sig=`SIGTERM`])
Send a signal to the given process group.

Parameters:

  • pgrp int group id to act on, or 0 for the sending process`s group
  • sig int signal to send (default `SIGTERM`)

Returns:

    int 0, if successful

Or

  1. nil
  2. string error message
  3. int errnum

See also:

raise (sig)
Raise a signal on this process.

Parameters:

  • sig int signal to send

Returns:

    int 0, if successful

Or

  1. nil
  2. string error message
  3. int errnum

See also:

signal (signum[, handler=SIG_DFL[, flags]])
Install a signal handler for this signal number. Although this is the same API as signal(2), it uses sigaction for guaranteed semantics.

Parameters:

  • signum int
  • handler function function, or SIG_IGN or SIG_DFL constants (default SIG_DFL)
  • flags the sa_flags element of struct sigaction (optional)

Returns:

    function previous handler function

See also:

Constants

posix.signal
Signal constants. Any constants not available in the underlying system will be nil valued.

Fields:

  • SIGABRT int abort ()
  • SIGALRM int alarm clock
  • SIGBUS int bus error
  • SIGCHLD int to parent on child stop or exit
  • SIGCONT int continue a stopped process
  • SIGFPE int floating point error
  • SIGHUP int hangup
  • SIGILL int illegal instruction
  • SIGINFO int information request
  • SIGINT int interrupt
  • SIGKILL int kill
  • SIGPIPE int write on pipe with no reader
  • SIGQUIT int quit
  • SIGSEGV int segmentation violation
  • SIGSTOP int stop
  • SIGSYS int bad argument to system call
  • SIGTERM int terminate
  • SIGTRAP int trace trap
  • SIGTSTP int stop signal from tty
  • SIGTTIN int to readers process group on background tty read
  • SIGTTOU int to readers process group on background tty output
  • SIGURG int urgent condition on i/o channel
  • SIGUSR1 int user defined
  • SIGUSR2 int user defined
  • SIGVTALRM int virtual time alarm
  • SIGWINCH int window size change
  • SIGXCPU int exceeded cpu time limit
  • SIGXFSZ int exceeded file size limit
  • SA_NOCLDSTOP int do not generate a SIGCHLD on child stop
  • SA_NOCLDWAIT int don't keep zombies child processes
  • SA_NODEFER int don't mask the signal we're delivering
  • SA_RESETHAND int reset to SIG_DFL when taking a signal
  • SA_RESTART int allow syscalls to restart instead of returning EINTR

Usage:

    -- Print signal constants supported on this host.
for name, value in pairs (require "posix.signal") do
  if type (value) == "number" then
    print (name, value)
   end
end
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