NAME
    apmsleep - go into suspend or standby mode and wake-up later

SYNOPSIS
    apmsleep  [-sSnwhVd] [--suspend] [--standby] [--noapm] [--wait] [--pre-
    cise] [--help] [--version] [--debug] [+]hh:mm

DESCRIPTION
    Some computers, especially laptops, can wake-up from a low-power sus-
    pend to  DRAM mode using the Real-time-clock (RTC) chip. Apmsleep can
    be used to set the alarm time in the RTC and to  go into suspend or
    standby mode. An interrupt from the RTC causes the computer to wake-up.
    The program detects this event, by waiting for a  leap in the kernel
    time and terminates successfully. If no time leap occurs within one
    minute, or something goes wrong, the exit value will be non-zero.

    The wake-up time can be specified in two formats:

    +hh:mm specifies a relative offset to the current time.  The computer
    will suspend for exactly hh hours and mm minutes plus a few seconds to
    wake up.  On some laptops, the timing is not completely accurate so it
    may be a few minutes (or more?) late.

    hh:mm specifies absolute local time in 24-hour format. The time stored
    in the RTC is not important. You may change the time zone used, with
    the TZ environment variable as usual. Daylight saving time is not
    obeyed in this version, but might be in a future release. WARNING: Do
    not close cover of laptop after suspending the laptop with apmsleep.
    Most laptops overheat when running with closed cover.

    Energy conservation with APM is little for a desktop. Turning of the
    screen will save 1/2, going into standby with drives turned off will
    save another 1/6th of the current.

    -V, --version
    Print the apmsleep program version and exit immediately.

    -s, --suspend
    Put the machine into suspend mode if possible (default). On my
    laptop, suspend mode turns off everything except the memory.

    -S, --standby
    Put the machine  into standby mode if possible. On my laptop,
    standby mode turns off screen, hard disk, and CPU.

    -w, --wait
    Wait indefinitely for the time leap.

    -p, --precise
    Wait for alarm time to match actual time. Do not wait for time
    leap. This might be useful even without APM.

    -n, --noapm
    Do not call apm bios to suspend computer, just set the alarm
    clock and wait for time leap indefinitely.

    -d, --debug
    Print some information about what is going on.

REQUIRED SYSTEM CONFIGURATION
    Kernel The special character device /dev/rtc must exist and the  Linux
    kernel  needs  to  be compiled with APM and RTC support
    (CONFIG_RTC, and relevant CONFIG_APM* options).

    BIOS  The computer must have the 'suspend to RAM' feature enabled in
    the BIOS; 'suspend to Disk' will not work, because the computer
    is turned off completely. You do not need to enable the  ALARM
    timer, it will be activated by apmsleep. On some boards, you can
    configure which interrupts can be used to awake  from suspend
    mode. If you have such a board, you might want to make sure that
    keyboard (IRQ 1) and RTC (IRQ 8) are among those interrupts. If
    your computer does not wake up, try to enable 'modem ring' in
    the BIOS, even if you do not have a modem.

    Privileges
    The program must be run as root or have the SUID attribute set
    (see chmod(1)).

BUGS
    Apmsleep  cannot detect which event terminated the suspension. Possible
    events are: keyboard or mouse activity, modem ring, alarm from RTC, any
    other interrupt. Sometimes, the time  leap is not detected properly
    (causing a wrong exit value).

    Should use APM BIOS calls to set alarm clock (not yet supported by ker-
    nel).

    This program was tested on a Winbook XL laptop (Pentium) only. It may
    not function on your hardware.

AUTHOR
    Written by Peter Englmaier (ppe@mpe.mpg.de) and  may be freely dis-
    tributed  under the terms of the GNU General Public License. The code
    is based on Paul Gortmacher's RTC test/example program. There is ABSO-
    LUTELY NO WARRANTY for this program. The current maintainer is Peter
    Englmaier.

SEE ALSO
    xapm(1), apmd(8),rtc.txt(Linux Kernel Documentation)