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



NAME
       adjtime - smoothly tune kernel clock

SYNOPSIS
       #include <sys/time.h>

       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 mono-
       tonically 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  adj-
       time  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  fail-
       ure 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(x)  function
       to permanently change the system clock speed.

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

SEE ALSO
       adjtimex(x), settimeofday(y)



Linux 2.0                   2002-02-16                 ADJTIME(E)