<sys/time.h>(P) POSIX Programmer's Manual <sys/time.h>(P)
sys/time.h - time types
The <sys/time.h> header shall define the timeval structure that includes at least the fol-
time_t tv_sec Seconds.
suseconds_t tv_usec Microseconds.
The <sys/time.h> header shall define the itimerval structure that includes at least the
struct timeval it_interval Timer interval.
struct timeval it_value Current value.
The time_t and suseconds_t types shall be defined as described in <sys/types.h> .
The fd_set type shall be defined as described in <sys/select.h> .
The <sys/time.h> header shall define the following values for the which argument of
getitimer() and setitimer():
Decrements in real time.
Decrements in process virtual time.
Decrements both in process virtual time and when the system is running on behalf of
The following shall be defined 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 select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
struct timeval *restrict);
int setitimer(int, const struct itimerval *restrict,
struct itimerval *restrict);
int utimes(const char *, const struct timeval ); (LEGACY )
Inclusion of the <sys/time.h> header may make visible all symbols from the <sys/select.h>
The following sections are informative.
<sys/select.h> , <sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001,
getitimer(), gettimeofday(), select(), setitimer()
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. 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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 <sys/time.h>(P)