|
|
1.1 ! root 1: .\" Copyright (c) 1983 Regents of the University of California. ! 2: .\" All rights reserved. The Berkeley software License Agreement ! 3: .\" specifies the terms and conditions for redistribution. ! 4: .\" ! 5: .\" @(#)signal.3f 6.1 (Berkeley) 5/15/85 ! 6: .\" ! 7: .TH SIGNAL 3F "May 15, 1985" ! 8: .UC 5 ! 9: .SH NAME ! 10: signal \- change the action for a signal ! 11: .SH SYNOPSIS ! 12: .B integer function signal(signum, proc, flag) ! 13: .br ! 14: .B integer signum, flag ! 15: .br ! 16: .B external proc ! 17: .SH DESCRIPTION ! 18: When a process incurs a signal (see ! 19: .IR signal (3C)) ! 20: the default action ! 21: is usually to clean up and abort. ! 22: The user may choose to write an alternative signal handling routine. ! 23: A call to ! 24: .I signal ! 25: is the way this alternate action is specified to the system. ! 26: .PP ! 27: .I Signum ! 28: is the signal number (see ! 29: .IR signal (3C)). ! 30: If ! 31: .I flag ! 32: is negative, then ! 33: .I proc ! 34: must be the name of the user signal handling routine. ! 35: If ! 36: .I flag ! 37: is zero or positive, then ! 38: .I proc ! 39: is ignored and the value of ! 40: .I flag ! 41: is passed to the system as the signal action definition. ! 42: In particular, this is how previously saved signal actions can be restored. ! 43: Two possible values for ! 44: .I flag ! 45: have specific meanings: ! 46: 0 means "use the default action" (See NOTES below), ! 47: 1 means "ignore this signal". ! 48: .PP ! 49: A positive returned value is the previous action definition. ! 50: A value greater than 1 is the address of a routine that ! 51: was to have been called on occurrence of the given signal. ! 52: The returned value can be used in subsequent calls to ! 53: .I signal ! 54: in order to restore a previous action definition. ! 55: A negative returned value is the negation of a system error code. ! 56: (See ! 57: .IR perror (3F)) ! 58: .SH FILES ! 59: .ie \nM /usr/ucb/lib/libU77.a ! 60: .el /usr/lib/libU77.a ! 61: .SH "SEE ALSO" ! 62: signal(3C), kill(3F), kill(1) ! 63: .SH NOTES ! 64: .B f77 ! 65: arranges to trap certain signals when a process is started. ! 66: The only way to restore the default ! 67: .B f77 ! 68: action is to save the returned ! 69: value from the first call to ! 70: .I signal. ! 71: .PP ! 72: If the user signal handler is called, it will be passed the signal number ! 73: as an integer argument.
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.