sys_time.h(0P) POSIX Programmer's Manual sys_time.h(0P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAME
sys/time.h — time types
SYNOPSIS
#include <sys/time.h>
DESCRIPTION
The <sys/time.h> header shall define the timeval structure, which shall
include at least the following members:
time_t tv_sec Seconds.
suseconds_t tv_usec Microseconds.
The <sys/time.h> header shall define the itimerval structure, which
shall include at least the following members:
struct timeval it_interval Timer interval.
struct timeval it_value Current value.
The <sys/time.h> header shall define the time_t and suseconds_t types
as described in <sys/types.h>.
The <sys/time.h> header shall define the fd_set type as described in
<sys/select.h>.
The <sys/time.h> header shall define the following symbolic constants
for the which argument of getitimer() and setitimer():
ITIMER_REAL Decrements in real time.
ITIMER_VIRTUAL
Decrements in process virtual time.
ITIMER_PROF Decrements both in process virtual time and when the sys‐
tem is running on behalf of the process.
The <sys/time.h> header shall define the following as described in
<sys/select.h>: FD_CLR()FD_ISSET()FD_SET()FD_ZERO() FD_SETSIZE
The following shall be declared as functions and may also be defined as
macros. Function prototypes shall be provided.
int getitimer(int, struct itimerval *);
int gettimeofday(struct timeval *restrict, void *restrict);
int setitimer(int, const struct itimerval *restrict,
struct itimerval *restrict);
int select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
struct timeval *restrict);
int utimes(const char *, const struct timeval [2]);
Inclusion of the <sys/time.h> header may make visible all symbols from
the <sys/select.h> header.
The following sections are informative.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
<sys_select.h>, <sys_types.h>
The System Interfaces volume of POSIX.1‐2008, futimens(), getitimer(),
gettimeofday(), pselect()COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 sys_time.h(0P)
