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

NAME

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

SYNOPSIS

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

DESCRIPTION

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.

REQUIRED SYSTEM CONFIGURATION

       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.

       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 kernel).

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

AUTHOR