time_t(3type)                                                    time_t(3type)

NAME
       time_t, suseconds_t, useconds_t - integer time

LIBRARY
       Standard C library (libc)

SYNOPSIS
       #include <time.h>

       typedef /* ... */  time_t;

       #include <sys/types.h>

       typedef /* ... */  suseconds_t;
       typedef /* ... */  useconds_t;

DESCRIPTION
       time_t Used for time in seconds.  According to POSIX, it is an integer
              type of at least 64 bits.

       suseconds_t
              Used for time in microseconds.  It is a signed integer type
              capable of storing values at least in the range [-1, 1000000].

       useconds_t
              Used for time in microseconds.  It is an unsigned integer type
              capable of storing values at least in the range [0, 1000000].

STANDARDS
       time_t C11, POSIX.1-2024.

       suseconds_t
              POSIX.1-2024.

       useconds_t
              None.

HISTORY
       time_t C89, POSIX.1-1988.

       suseconds_t
              SUSv2, POSIX.1-2001 XSI, POSIX.1-2024.

       useconds_t
              SUSv1, POSIX.1-2001 XSI.  Removed in POSIX.1-2008.

   Header files
       <sched.h> defines time_t since POSIX.1-2008.

   time_t
       POSIX.1-2024 requires that the width of time_t is at least 64 bits;
       however, some systems still use 32 bits by default.

NOTES
       On some architectures, the width of time_t can be controlled with the
       feature test macro _TIME_BITS.  See feature_test_macros(7).

       The following headers also provide time_t: <sched.h>, <sys/msg.h>,
       <sys/select.h>, <sys/sem.h>, <sys/shm.h>, <sys/stat.h>, <sys/time.h>,
       <sys/types.h>, and <utime.h>.

       The following headers also provide suseconds_t: <sys/select.h> and
       <sys/time.h>.

       The following headers also provided useconds_t: <unistd.h>.

SEE ALSO
       stime(2), time(2), ctime(3), difftime(3), usleep(3), timeval(3type)

Linux man-pages 6.19              2026-02-08                     time_t(3type)