TIME(3) BSD Library Functions Manual TIME(3)
time -- get time of day
Standard C Library (libc, -lc)
The time() function returns the value of time in seconds since 0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal Time,
without including leap seconds. If an error occurs, time() returns the value (time_t)-1.
The return value is also stored in *tloc, provided that tloc is non-null.
The time() function may fail for any of the reasons described in gettimeofday(2).
The time function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
A time() function appeared in Version 6 AT&T UNIX.
Neither ISO/IEC 9899:1999 (``ISO C99'') nor IEEE Std 1003.1-2001 (``POSIX.1'') requires time() to set errno on failure; thus, it is impossi-
ble for an application to distinguish the valid time value -1 (representing the last UTC second of 1969) from the error return value.
Systems conforming to earlier versions of the C and POSIX standards (including older versions of FreeBSD) did not set *tloc in the error
July 18, 2003 BSD