mirror of https://github.com/mkerrisk/man-pages
129 lines
3.0 KiB
Groff
129 lines
3.0 KiB
Groff
.\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" 2007-07-31, mtk, Created
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.\"
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.TH TIMERADD 3 2007-07-31 "Linux" "Linux Programmer's Manual"
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.SH NAME
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timeradd, timersub, timercmp, timerclear, timerisset \- timeval operations
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.SH SYNOPSIS
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.nf
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.B #include <sys/time.h>
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.BI "void timeradd(struct timeval *" a ", struct timeval *" b ,
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.BI " struct timeval *" res );
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.BI "void timersub(struct timeval *" a ", struct timeval *" b ,
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.BI " struct timeval *" res );
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.BI "void timerclear(struct timeval *" tvp );
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.BI "void timerisset(struct timeval *" tvp );
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.BI "void timercmp(struct timeval *" a ", struct timeval *" b ", " CMP );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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All functions shown above require:
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_BSD_SOURCE
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.SH DESCRIPTION
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The macros are provided to operate on
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.I timeval
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structures, defined in
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.I <sys/time.h>
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as:
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.sp
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.in +4n
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.nf
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struct timeval {
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time_t tv_sec; /* seconds */
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suseconds_t tv_usec; /* microseconds */
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};
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.fi
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.in
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.PP
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.BR timeradd ()
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adds the time values in
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.I a
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and
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.IR b ,
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and places the sum in the
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.I timeval
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pointed to by
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.IR res .
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The result is normalized such that
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.I res->tv_usec
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has a value in the range 0 to 999,999.
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.BR timersub ()
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subtracts the time value in
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.I b
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from the time value in
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.IR a ,
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and places the result in the
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.I timeval
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pointed to by
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.IR res .
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The result is normalized such that
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.I res->tv_usec
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has a value in the range 0 to 999,999.
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.BR timerclear ()
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zeroes out the
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.I timeval
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structure pointed to by
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.IR tvp ,
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so that it represents the time at midnight
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on the morning of 1 January 1970 (the Epoch).
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.BR timerisset ()
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returns true (non-zero) if either field of the
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.I timeval
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structure pointed to by
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.I tvp
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contains a non-zero value.
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.BR timercmp ()
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compares the timer values in
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.I a
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and
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.I b
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using the comparison operator
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.IR CMP ,
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and returns true (non-zero) or false (0) depending on
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the result of the comparison.
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.SH RETURN VALUE
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.BR timerisset ()
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and
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.BR timercmp ()
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return true (non-zero) or false (0).
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.BR
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.SH ERRORS
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No errors are defined.
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.SH CONFORMING TO
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Not in POSIX.1-2001.
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Present on most BSD derivatives.
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.SH "SEE ALSO"
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.BR gettimeofday (2),
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.BR time (7).
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