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


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


       Some computers,  especially  laptops,  can  wake-up  from  a  low-power
       suspend  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.


       Kernel The special character device /dev/rtc must exist and the  kernel
              needs to be compiled with APM and RTC support.

       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.

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


       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

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


       Written   by   Peter  Englmaier  (  and  may  be  freely
       distributed under the terms of the GNU  General  Public  License.   The
       code  is based on Paul Gortmacher’s RTC test/example program.  There is
       ABSOLUTELY NO WARRANTY for this program.   The  current  maintainer  is
       Peter Englmaier.


       xapm(1), apmd(8).

                                 January 2004