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ADJTIME(2) System Calls Manual ADJTIME(2) NAME adjtime -- correct the time to allow synchronization of the system clock LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <sys/time.h> int adjtime(const struct timeval *delta, struct timeval *olddelta); DESCRIPTION The adjtime() system call makes small adjustments to the system time, as returned by gettimeofday(2), advancing or retarding it by the time speci- fied by the timeval delta. If delta is negative, the clock is slowed down by incrementing it more slowly than normal until the correction is com- plete. If delta is positive, a larger increment than normal is used. The skew used to perform the correction is generally a fraction of one percent. Thus, the time is always a monotonically increasing function. A time cor- rection from an earlier call to adjtime() may not be finished when adj- time() is called again. If olddelta is not a null pointer, the structure pointed to will contain, upon return, the number of microseconds still to be corrected from the earlier call. This call may be used by time servers that synchronize the clocks of com- puters in a local area network. Such time servers would slow down the clocks of some machines and speed up the clocks of others to bring them to the average network time. The adjtime() system call is restricted to the super-user. RETURN VALUES The adjtime() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. ERRORS The adjtime() system call will fail if: [EFAULT] An argument points outside the process's allocated ad- dress space. [EPERM] The process's effective user ID is not that of the su- per-user. SEE ALSO date(1), gettimeofday(2) R. Gusella and S. Zatti, TSP: The Time Synchronization Protocol for UNIX 4.3BSD. HISTORY The adjtime() system call appeared in 4.3BSD. FreeBSD ports 15.quarterly May 13, 2021 ADJTIME(2)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY
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