Module: Signal
Relationships & Source Files | |
Defined in: | signal.c |
Overview
Many operating systems allow signals to be sent to running processes. Some signals have a defined effect on the process, while others may be trapped at the code level and acted upon. For example, your process may trap the USR1 signal and use it to toggle debugging, and may use TERM to initiate a controlled shutdown.
pid = fork do
Signal.trap("USR1") do
$debug = !$debug
puts "Debug now: #$debug"
end
Signal.trap("TERM") do
puts "Terminating..."
shutdown()
end
# . . . do some work . . .
end
Process.detach(pid)
# Controlling program:
Process.kill("USR1", pid)
# ...
Process.kill("USR1", pid)
# ...
Process.kill("TERM", pid)
produces:
Debug now: true
Debug now: false
Terminating...
The list of available signal names and their interpretation is system dependent. Signal
delivery semantics may also vary between systems; in particular signal delivery may not always be reliable.
Class Method Summary
-
.list ⇒ Hash
mod_func
Returns a list of signal names mapped to the corresponding underlying signal numbers.
-
.signame(signo) ⇒ String?
mod_func
Convert signal number to signal name.
-
.trap(*args)
mod_func
Alias for Kernel.trap.
Class Method Details
.list ⇒ Hash (mod_func)
Returns a list of signal names mapped to the corresponding underlying signal numbers.
Signal.list #=> {"EXIT"=>0, "HUP"=>1, "INT"=>2, "QUIT"=>3, "ILL"=>4, "TRAP"=>5, "IOT"=>6, "ABRT"=>6, "FPE"=>8, "KILL"=>9, "BUS"=>7, "SEGV"=>11, "SYS"=>31, "PIPE"=>13, "ALRM"=>14, "TERM"=>15, "URG"=>23, "STOP"=>19, "TSTP"=>20, "CONT"=>18, "CHLD"=>17, "CLD"=>17, "TTIN"=>21, "TTOU"=>22, "IO"=>29, "XCPU"=>24, "XFSZ"=>25, "VTALRM"=>26, "PROF"=>27, "WINCH"=>28, "USR1"=>10, "USR2"=>12, "PWR"=>30, "POLL"=>29}
# File 'signal.c', line 1393
static VALUE sig_list(VALUE _) { VALUE h = rb_hash_new(); const struct signals *sigs; FOREACH_SIGNAL(sigs, 0) { rb_hash_aset(h, rb_fstring_cstr(sigs->signm), INT2FIX(sigs->signo)); } return h; }
.signame(signo) ⇒ String? (mod_func)
# File 'signal.c', line 308
static VALUE sig_signame(VALUE recv, VALUE signo) { const char *signame = signo2signm(NUM2INT(signo)); if (!signame) return Qnil; return rb_str_new_cstr(signame); }
.trap(*args) (mod_func)
Alias for Kernel.trap.