SYS_SELECT.H(7) Miscellaneous Information Manual SYS_SELECT.H(7)

NAME

sys/select.h — select types

SYNOPSIS

#include <sys/select.h>

DESCRIPTION

The <sys/select.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/select.h> header shall define the time_t and suseconds_t types as described in <sys/types.h>.

The <sys/select.h> header shall define the sigset_t type as described in <signal.h>.

The <sys/select.h> header shall define the timespec structure as described in <time.h>.

The <sys/select.h> header shall define the fd_set type as a structure.

The <sys/select.h> header shall define the following symbolic constant, which shall have a value suitable for use in #if preprocessing directives:

FD_SETSIZE: Maximum number of file descriptors in an fd_set structure.

The following shall be declared as functions, defined as macros, or both. If functions are declared, function prototypes shall be provided.

void FD_CLR(int, fd_set *);
int  FD_ISSET(int, const fd_set *);
void FD_SET(int, fd_set *);
void FD_ZERO(fd_set *);

If implemented as macros, these may evaluate their arguments more than once, so applications should ensure that the arguments they supply are never expressions with side-effects.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

int  pselect(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
         const struct timespec *restrict, const sigset_t *restrict);
int  select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
         struct timeval *restrict);

Inclusion of the <sys/select.h> header may make visible all symbols from the headers <signal.h> and <time.h>.

The following sections are informative.