The <sys/select.h> header defines the timeval structure, which includes the following members:
time_t tv_sec /* seconds */ suseconds_t tv_usec /* microseconds */
The time_t and suseconds_t types are defined as described in <sys/types.h>. See types.h(3HEAD).
The sigset_t type is defined as described in signal.h(3HEAD).
The timespec structure is defined as described in <time.h>. See time.h(3HEAD).
The <sys/select.h> header defines the fd_set type as a structure.
The following is defined as a macro:
Maximum number of file descriptors in an fd_set structure.
Inclusion of the <sys/select.h> header can make visible all symbols from the headers <signal.h>, <sys/time.h>, and <time.h>.
See attributes(5) for descriptions of the following attributes: