acpid: Advanced Configuration and Power Interface event daemon - Linux Manuals (8) (2024)

acpid: Advanced Configuration and Power Interface event daemon

Command to display acpid manual in Linux: $ man 8 acpid

NAME

acpid - Advanced Configuration and Power Interface event daemon

SYNOPSIS

acpid [options]

DESCRIPTION

acpid is designed to notify user-space programs of ACPI events.acpid should be started during the system boot, and will run as abackground process, by default. It will open an events file(/proc/acpi/event by default) and attempt to read whole lines whichrepresent ACPI events. If the events file does not exist, acpid willattempt to connect to the Linux kernel via the input layer and netlink. When anACPI event is received from one of these sources, acpid will examine alist of rules, and execute the rules that match the event. acpid willignore all incoming ACPI events if a lock file exists (/var/lock/acpid bydefault).

Rules are defined by simple configuration files. acpidwill look in a configuration directory (/etc/acpi/events by default),and parse all regular files with names that consist entirely of upper andlower case letters, digits, underscores, and hyphens (similar torun-parts(8))that do not begin with a period ('.') or end with a tilde (~).Each file must define two things: an event and anaction. Any blank lines, or lines where the first character is ahash ('#') are ignored. Extraneous lines are flagged as warnings, butare not fatal. Each line has three tokens: the key, a literal equal sign,and the value. The key can be up to 63 characters, and is case-insensitive(but whitespace matters). The value can be up to 511 characters, and iscase and whitespace sensitive.

The event value is a regular expression (seeregcomp(3)),against which events are matched.

The action value is a commandline, which will be invoked via /bin/shwhenever an event matching the rule in question occurs. The commandline mayinclude shell-special characters, and they will be preserved. The only specialcharacters in an action value are "%" escaped. The string "%e" will bereplaced by the literal text of the event for which the action was invoked.This string may contain spaces, so the commandline must take care to quote the "%e" if it wants a single token. The string "%%" will be replaced by aliteral "%". All other "%" escapes are reserved, and will cause a rule tonot load.

This feature allows multiple rules to be defined for the same event (though noordering is guaranteed), as well as one rule to be defined for multiple events.To force acpid to reload the rule configuration, send it a SIGHUP.

The pseudo-action <drop> causes the event to be droppedcompletely and no further processing undertaken; clients connectingvia the UNIX domain socket (see below) will not be notified of theevent. This may be useful on some machines, such as certain laptops whichgenerate spurious battery events at frequent intervals. The name ofthis pseudo-action may be redefined with a commandline option.

In addition to rule files, acpid also accepts connections on a UNIXdomain socket (/var/run/acpid.socket by default). Any application mayconnect to this socket. Once connected, acpid will send the text ofall ACPI events to the client. The client has the responsibility of filteringfor messages about which it cares. acpid will not close the clientsocket except in the case of a SIGHUP or acpid exiting.

For faster startup, this socket can be passed in as stdin so that acpidneed not create the socket. In addition, if a socket is passed in as stdin, acpid will not daemonize. It will be run in foreground. This behavior is provided to supportsystemd(1).

acpidwill log all of its activities, as well as the stdout and stderr of anyactions, to syslog.

All the default files and directories can be changed with commandline options.

OPTIONS

-c, --confdir directory

This option changes the directory in which acpid looks for ruleconfiguration files. Default is /etc/acpi/events.

-C, --clientmax number

This option changes the maximum number of non-root socket connections whichcan be made to the acpid socket. Default is 256.

-d, --debug

This option increases the acpid debug level by one.

-e, --eventfile filename

This option changes the event file from which acpid reads events.Default is /proc/acpi/event.

-n, --netlink

This option forces acpid to use the Linux kernel input layer and netlink interface for ACPI events.

-f, --foreground

This option keeps acpid in the foreground by not forking at startup,and makes it log to stderr instead of syslog.

-l, --logevents

This option tells acpid to log information about all events and actions.

-L, --lockfile filename

This option changes the lock file used to stop event processing.Default is /var/lock/acpid.

-g, --socketgroup groupname

This option changes the group ownership of the UNIX domain socket to whichacpid publishes events.

-m, --socketmode mode

This option changes the permissions of the UNIX domain socket to whichacpid publishes events. Default is 0666.

-s, --socketfile filename

This option changes the name of the UNIX domain socket which acpid opens.Default is /var/run/acpid.socket.

-S, --nosocket

This option tells acpid not to open a UNIX domain socket. Thisoverrides the -s option, and negates all other socket options.

-p, --pidfile filename

This option tells acpid to use the specified file as its pidfile. Ifthe file exists, it will be removed and over-written.Default is /var/run/acpid.pid.

-r, --dropaction action

This option defines the pseudo-action which tells acpid to abortall processing of an event, including client notifications.Default is <drop>.

-t, --tpmutefix

This option enables special handling of the mute button for certainThinkPad models with mute LEDs that get out of sync with the mute statewhen the mute button is held down. With this option, the mute buttonwill generate the following events in sync with the number of presses(and, by extension, the state of the LED):

button/mute MUTE (key pressed) K
button/mute MUTE (key released) K

-v, --version

Print version information and exit.

-h, --help

Show help and exit.

EXAMPLE

This example will shut down your system if you press the power button.

Create a file named /etc/acpi/events/power that contains the following:

event=button/power
action=/etc/acpi/power.sh "%e"

Then create a file named /etc/acpi/power.sh that contains the following:

/sbin/shutdown -h now "Power button pressed"

Now, when acpid is running, a press of the power button will cause therule in /etc/acpi/events/power to trigger the script in /etc/acpi/power.sh.The script will then shut down the system.

TROUBLESHOOTING

acpid is a simple program that runs scripts in response to ACPIevents from the kernel. When there's trouble, the problem is rarelywith acpid itself. The following are some suggestions forfinding the most common sources of ACPI-related problems.

When troubleshooting acpid, it is important to be aware that other partsof a system might be handling ACPI events.systemd(1)is capable of handling the power switch and various otherevents that are commonly handled by acpid. See the description ofHandlePowerKey inlogind.conf(5)for more. Some window managers alsotake over acpid's normal handling of the power button and other events.

kacpimon(8)can be used to verify that the expected ACPI events arecoming in. See the man page forkacpimon(8)for the proper procedure.If the events aren'tcoming in, you've probably got a kernel driver issue.

If the expected events are coming in, then you'll needto check and see if your window manager is responsible forhandling these events. Some are, some aren't. (E.g. in Ubuntu14.04 (Unity/GNOME), there are settings for the laptop lid in theSystem Settings > Power > "When the lid is closed" fields.)If your window manager is responsible for handling the problematicevent, and you've got it configured properly, then you may have awindow manager issue.

Lastly, take a look in /etc/acpi/events (see above). Is therea configuration file in there for the eventin question (e.g. /etc/acpi/events/lidbtn for laptop lid open/closeevents)? Is it properly connected to ascript (e.g. /etc/acpi/lid.sh)? Is that script working? It's notunusual for an acpid script to check and see if there is a windowmanager running, then do nothing if there is. This means it is upto the window manager to handle this event.

DEPENDENCIES

acpid should work on any linux kernel released since 2003.

FILES

/proc/acpi/event
/dev/input/event*
/etc/acpi/
/var/run/acpid.socket
/var/run/acpid.pid
/var/lock/acpid

BUGS

There are no known bugs. To file bug reports, see PROJECT WEBSITE below.

PROJECT WEBSITE

http://sourceforge.net/projects/acpid2/

AUTHORS

Ted Felix <ted [at] tedfelix.com>
Tim Hockin <thockin [at] hockin.org>
Andrew Henroid