mirror of https://github.com/mkerrisk/man-pages
112 lines
3.2 KiB
Groff
112 lines
3.2 KiB
Groff
.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, write to the Free
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.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
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.\" USA.
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.\"
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.TH UALARM 3 2003-07-24 "" "Linux Programmer's Manual"
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.SH NAME
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ualarm \- schedule signal after given number of microseconds
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.SH SYNOPSIS
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.nf
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/* BSD version */
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.B "#include <unistd.h>"
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.sp
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.BI "unsigned int"
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.br
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.BI "ualarm(unsigned int " usecs ", unsigned int " interval );
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.sp
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/* SUSv2 version */
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.B "#define _XOPEN_SOURCE 500"
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.br
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.B "#include <unistd.h>"
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.sp
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.BI "useconds_t ualarm(useconds_t " usecs ", useconds_t " interval );
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.fi
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.SH DESCRIPTION
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The \fBualarm()\fP function causes the signal SIGALRM to be sent
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to the invoking process after (not less than)
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.I usecs
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microseconds.
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The delay may be lengthened slightly by any system activity
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or by the time spent processing the call or by the
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granularity of system timers.
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.LP
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Unless caught or ignored, this signal will terminate the process.
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.LP
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If the
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.I interval
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argument is nonzero, further SIGALRM signals will be sent every
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.I interval
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microseconds after the first.
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.SH "RETURN VALUE"
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This function returns the number of microseconds remaining from
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the previous call, or 0 when no alarm is pending.
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.SH ERRORS
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.TP
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EINTR
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Interrupted by a signal.
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.TP
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EINVAL
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\fIusecs\fP or \fIinterval\fP is not smaller than 1000000.
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(On systems where that is considered an error.)
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.SH "CONFORMING TO"
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BSD 4.3, POSIX 1003.1-2003.
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BSD 4.3, SUSv2 and POSIX do not define any errors.
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.SH NOTES
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The type
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.B useconds_t
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is an unsigned integer type capable of holding integers
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in the range [0,1000000].
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This type is defined by
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.I <sys/types.h>
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included by
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.I <unistd.h>
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but glibc defines it only when _XOPEN_SOURCE has a value not less than 500,
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or both _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED are defined.
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.\" useconds_t also gives problems on HPUX 10.
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Programs will be more portable if they never mention this type explicitly.
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.LP
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The interaction of this function with
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other timer functions such as
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.IR alarm (),
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.IR sleep (),
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.IR nanosleep (),
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.IR setitimer (),
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.IR timer_create (),
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.IR timer_delete (),
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.IR timer_getoverrun (),
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.IR timer_gettime (),
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.IR timer_settime (),
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.IR usleep ()
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is unspecified.
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.LP
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This function is obsolete. Use
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.BR nanosleep (2)
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or
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.BR setitimer (2)
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instead.
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.SH "SEE ALSO"
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.BR alarm (2),
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.BR getitimer (2),
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.BR nanosleep (2),
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.BR select (2),
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.BR setitimer (2),
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.BR usleep (3)
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