ACPID
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Acpid is a daemon that executes certain actions whenever ACPI events are
received. Depending on your hardware and kernel configuration, these events
include closing a laptop lid, connecting to an AC power adapter, pressing
buttons and more.
Index
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- Usage [0.0]
- Kernel Setup [1.0]
- Busybox acpid [2.0]
- acpid2 [3.0]
[0.0] Usage
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KISS Linux offers two options for acpid management: busybox acpid, which is
installed by default, and acpid2 [1], which can be installed with the acpid
package. To use either version of acpid, you will need to enable a few kernel
options and enable the acpid service. See @/init/busybox.
[1.0] Kernel Setup
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ACPI-related kernel drivers must be enabled for acpid to function properly. In
menuconfig, these options are found under Power management and ACPI options
> Power Management support > ACPI support. Most of the drivers are
self-explanatory, but the following notable options can be safely disabled:
+------------------------------------------------------------------------------+
| |
| CONFIG_ACPI_PROCFS_POWER This option is deprecated |
| CONFIG_ACPI_EC_DEBUGFS Potentially interferes with reboot |
| CONFIG_ACPI_TABLE_UPGRADE KISS does not use an initrd by default |
| CONFIG_ACPI_DEBUG Adds 50k to kernel size |
| CONFIG_ACPI_PCI_SLOT Usually unnecessary |
| CONFIG_ACPI_CUSTOM_METHOD Potential security flaw |
| |
+------------------------------------------------------------------------------+
[2.0] Busybox acpid
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When events are received, acpid checks /etc/acpi.map for a matching event and
/etc/acpid.conf for a corresponding handler script in /etc/acpi/ to execute.
Create the files below to suspend your laptop whenever the lid is closed:
+------------------------------------------------------------------------------+
| /etc/acpi.map |
+------------------------------------------------------------------------------+
| |
| EV_SW 0x05 SW_LID 0 1 button/lid LID0 00000080 |
| |
+------------------------------------------------------------------------------+
| /etc/acpid.conf |
+------------------------------------------------------------------------------+
| |
| LID0 LID/00000080 |
| |
+------------------------------------------------------------------------------+
| /etc/acpi/LID/00000080 |
+------------------------------------------------------------------------------+
| |
| #!/bin/sh |
| |
| printf mem > /sys/power/state |
| |
+------------------------------------------------------------------------------+
Each line in /etc/acpi.map has six space-delimited fields:
1. Type name (EV_SW),
2. Type numerical value (0x05)
3. Keycode name (SW_LID)
4. Keycode numerical value (0)
5. Value (1)
6. Description (button/lid LID0 00000080)
Event types and keycodes are listed in /usr/include/linux/input-event-codes.h.
For example, a keyboard WLAN button event would use EV_KEY 0x05 and KEY_WLAN
238. The event value should be 1 and the event description can be any string
potentially including spaces.
Each line in /etc/acpid.conf has a key (LID0) and an action (LID/00000080). The
key is any unique substring of the event description in /etc/acpi.map and the
action is the relative path to an executable script in /etc/acpi/.
To see if a configured event is received, check /var/log/acpid.log for output
lines that list the path of your handler scripts.
[3.0] acpid2
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acpid2 is a more user-friendly version of acpid that avoids the tedious process
of mapping events with flexible configuration and better documentation. The
acpid package also installs acpi_listen which prints events as they occur. For
example, pressing the volume mute button will print something like this:
+------------------------------------------------------------------------------+
| |
| button/mute MUTE 00000080 00000000 K |
| |
+------------------------------------------------------------------------------+
When events are received, acpid2 checks files in /etc/acpi/event/ for a matching
event and a corresponding handler script to execute. Create the following files
to handle the mute button event by toggling the Master audio channel:
+------------------------------------------------------------------------------+
| /etc/acpi/event/anything |
+------------------------------------------------------------------------------+
| |
| event=.* |
| action=/etc/acpi/handler.sh %e |
| |
+------------------------------------------------------------------------------+
| /etc/acpi/handler.sh |
+------------------------------------------------------------------------------+
| |
| #!/bin/sh |
| |
| case $1 in |
| button/mute) |
| amixer sset Master toggle |
| ;; |
| esac |
| |
+------------------------------------------------------------------------------+
Files in /etc/acpi/event/ match events using event=REGEX with an action to
execute. In this example, .* matches all events and the action executes
/etc/acpi/handler.sh. The argument %e expands to five event parameters:
$1=button/mute, $2=MUTE, $3=00000080, $4=00000000, $5=K. The event parameters
provide an easy way to handle all events in a single script instead of the more
complex multi-file system used by busybox.
References
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[0] https://sourceforge.net/projects/acpid2