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Annotation of 43BSDTahoe/man/man3f/signal.3, revision 1.1

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.

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