NAME

sys/time.h — time types

SYNOPSIS

^[XSI] #include <sys/time.h>

DESCRIPTION

The <sys/time.h> header shall define the fd_set type and the timeval structure, as described in <sys/select.h>.

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 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   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.

APPLICATION USAGE

None.

RATIONALE

The <sys/time.h> header refers to <sys/select.h> for the definition of the timeval structure, instead of the other way round, because <sys/time.h> is an optional (XSI) header whereas <sys/select.h> is mandatory.

FUTURE DIRECTIONS

None.

SEE ALSO

<sys/select.h> , <sys/types.h>

XSH futimens , pselect

CHANGE HISTORY

First released in Issue 4, Version 2.

Issue 5

The type of tv_usec is changed from long to suseconds_t.

Issue 6

The restrict keyword is added to the prototypes for gettimeofday(), select(), and setitimer().

The note is added that inclusion of this header may also make symbols visible from <sys/select.h>.

The utimes() function is marked LEGACY.

Issue 7

This reference page is clarified with respect to macros and symbolic constants.

Issue 8

Austin Group Defect 1171 is applied, replacing the timeval structure definition with a reference to its description in <sys/select.h>.

Austin Group Defect 1330 is applied, removing obsolescent interfaces.