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clock_settime ()
  • >> clock_settime (2) ( FreeBSD man: Системные вызовы )
  • clock_settime (2) ( Linux man: Системные вызовы )
  • clock_settime (3) ( Solaris man: Библиотечные вызовы )
  • clock_settime (3) ( Linux man: Библиотечные вызовы )
  • clock_settime (3) ( POSIX man: Библиотечные вызовы )

  • BSD mandoc
     

    NAME

    
    
    clock_gettime
    
     
    clock_settime
    
     
    clock_getres
    
     - get/set/calibrate date and time
    
     
    

    LIBRARY

    Lb libc
    
     
    

    SYNOPSIS

       #include <time.h>
    int clock_gettime (clockid_t clock_id struct timespec *tp);
    int clock_settime (clockid_t clock_id const struct timespec *tp);
    int clock_getres (clockid_t clock_id struct timespec *tp);
     

    DESCRIPTION

    The clock_gettime ();
    and clock_settime ();
    system calls allow the calling process to retrieve or set the value used by a clock which is specified by Fa clock_id .

    The Fa clock_id argument can be one of five values: CLOCK_REALTIME for time that increments as a wall clock should, CLOCK_MONOTONIC which increments in SI seconds, CLOCK_UPTIME which starts at zero when the kernel boots and increments monotonically in SI seconds while the machine is running, CLOCK_VIRTUAL for time that increments only when the CPU is running in user mode on behalf of the calling process, or CLOCK_PROF for time that increments when the CPU is running in user or kernel mode.

    The structure pointed to by Fa tp is defined in    #include <sys/timespec.h>
    as:

    struct timespec {
            time_t  tv_sec;         /* seconds */
            long    tv_nsec;        /* and nanoseconds */
    };
    

    Only the super-user may set the time of day. If the system securelevel is greater than 1 (see init(8)), the time may only be advanced. This limitation is imposed to prevent a malicious super-user from setting arbitrary time stamps on files. The system time can still be adjusted backwards using the adjtime(2) system call even when the system is secure.

    The resolution (granularity) of a clock is returned by the clock_getres ();
    system call. This value is placed in a (non-NULL) Fa *tp .  

    RETURN VALUES

    Rv -std  

    ERRORS

    The following error codes may be set in errno

    Bq Er EINVAL
    The Fa clock_id argument was not a valid value.
    Bq Er EFAULT
    The Fa *tp argument address referenced invalid memory.
    Bq Er EPERM
    A user other than the super-user attempted to set the time.

     

    SEE ALSO

    date(1), adjtime(2), ctime(3), timed(8)  

    STANDARDS

    The clock_gettime (,);
    clock_settime (,);
    and clock_getres ();
    system calls conform to St -p1003.1b-93 .


     

    Index

    NAME
    LIBRARY
    SYNOPSIS
    DESCRIPTION
    RETURN VALUES
    ERRORS
    SEE ALSO
    STANDARDS


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