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ADJTIME(2)                 Linux Programmer's Manual                ADJTIME(2)



NAME
       adjtime - smoothly tune kernel clock

SYNOPSIS
       #include <&lt;sys/time.h>&gt;

       int adjtime(const struct timeval *delta, struct timeval *olddelta);

DESCRIPTION
       This function speeds up or slows down the system clock in order to make
       a gradual adjustment.  This ensures that the calendar time reported  by
       the  system  clock  is always monotonically increasing, which might not
       happen if you simply set the clock.

       The delta argument specifies a relative adjustment to be  made  to  the
       clock  time.   If  negative, the system clock is slowed down fora while
       until it has lost this much elapsed  time.   If  positive,  the  system
       clock is speeded up for a while.

       If  the  olddelta  argument is not a null pointer, the adjtime function
       returns information about any previous time adjustment that has not yet
       completed.

       This  function is typically used to synchronize the clocks of computers
       in a local network.  You must be a privileged user to use it.

RETURN VALUE
       The adjtime function returns 0 on success and -1 on  failure  and  sets
       the external variable errno accordingly.

ERRORS
       EPERM  The  calling  process  does not have enough privileges to access
              the clock.

NOTE
       With a Linux kernel, you can use the  adjtimex(2)  function  to  perma-
       nently change the system clock speed.

CONFORMING TO
       This function is derived from 4.3 BSD and SVr4.

SEE ALSO
       adjtimex(2), settimeofday(2)



Linux 2.0                         2002-02-16                        ADJTIME(2)