adjtime.2 (2010 09)

adjtime(2) adjtime(2)

[EPERM] if the process does not have the appropriate privilege.

[EFAULT] The address speciﬁed for delta (or olddelta ) is invalid.

[EINVAL] If delta.tv_sec is greater than 31536000 (approx. 365 days) or less than −31536000.

The delta.tv_usec ﬁeld is not used in calculation of these limits. If the user wants to

adjust time greater than these limits, an appropriate alternative interface should be

used.

EXAMPLES

The following code snippet will take the time forward 20 minutes.

struct timeval forward;

forward.tv_sec = 20 * 60; /* 20 minutes */

forward.tv_usec = 0;

if (adjtime(&forward, (struct timeval *)NULL) == -1)

perror("adjtime() failure");

* If adjtime() succeeds, the system time will move forward

* 20 minutes over a period of time.

The following code fragment will repeatedly call a user-deﬁned function

adjustment_still_in_progress()

until the adjustment requested in a previous call to adj-

time() (called from either the same process or another process) is completed.

struct timeval report;

if (adjtime((struct timeval *)NULL, &report) == -1)

perror("adjtime() failure");

while (report.tv_sec || report.tv_usec) {

adjustment_still_in_progress();

if (adjtime((struct timeval *)NULL, &report) == -1)

perror("adjtime() failure");

}

AUTHOR

adjtime() was developed by the University of California, Berkeley and AT&T.