acpid(8)                    System Manager's Manual                   acpid(8)

       acpid - Advanced Configuration and Power Interface event daemon

       acpid [options]

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

       Rules are defined by simple configuration files.  acpid will look in a
       configuration directory (/etc/acpi/events by default), and parse all
       regular files with names that consist entirely of upper and lower case
       letters, digits, underscores, and hyphens (similar to run-parts(8))
       that do not begin with a period ('.') or end with a tilde (~).  Each
       file must define two things: an event and an action.  Any blank lines,
       or lines where the first character is a hash ('#') are ignored.
       Extraneous lines are flagged as warnings, but are 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 is case and
       whitespace sensitive.

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

       The action value is a commandline, which will be invoked via /bin/sh
       whenever an event matching the rule in question occurs.  The
       commandline may include shell-special characters, and they will be
       preserved.  The only special characters in an action value are "%"
       escaped.  The string "%e" will be replaced 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 a literal "%".
       All other "%" escapes are reserved, and will cause a rule to not load.

       This feature allows multiple rules to be defined for the same event
       (though no ordering 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 dropped completely and
       no further processing undertaken; clients connecting via the UNIX
       domain socket (see below) will not be notified of the event. This may
       be useful on some machines, such as certain laptops which generate
       spurious battery events at frequent intervals. The name of this pseudo-
       action may be redefined with a commandline option.

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

       For faster startup, this socket can be passed in as stdin so that acpid
       need 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 support systemd(1).

       acpid will log all of its activities, as well as the stdout and stderr
       of any actions, to syslog.

       All the default files and directories can be changed with commandline

       -c, --confdir directory
                   This option changes the directory in which acpid looks for
                   rule configuration files.  Default is /etc/acpi/events.

       -C, --clientmax number
                   This option changes the maximum number of non-root socket
                   connections which can 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 which acpid publishes events.

       -m, --socketmode mode
                   This option changes the permissions of the UNIX domain
                   socket to which acpid 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 filename
                   This option tells acpid not to open a UNIX domain socket.
                   This overrides the -s option, and negates all other socket

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

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

       -t, --tpmutefix
                   This option enables special handling of the mute button for
                   certain ThinkPad models with mute LEDs that get out of sync
                   with the mute state when the mute button is held down.
                   With this option, the mute button will 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.

       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:

              action=/etc/acpi/ "%e"

       Then create a file named /etc/acpi/ that contains the

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

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

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

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

       kacpimon(8) can be used to verify that the expected ACPI events are
       coming in.  See the man page for kacpimon(8) for the proper procedure.
       If the events aren't coming in, you've probably got a kernel driver

       If the expected events are coming in, then you'll need to check and see
       if your window manager is responsible for handling these events.  Some
       are, some aren't.  (E.g. in Ubuntu 14.04 (Unity/GNOME), there are
       settings for the laptop lid in the System Settings > Power > "When the
       lid is closed" fields.)  If your window manager is responsible for
       handling the problematic event, and you've got it configured properly,
       then you may have a window manager issue.

       Lastly, take a look in /etc/acpi/events (see above).  Is there a
       configuration file in there for the event in question (e.g.
       /etc/acpi/events/lidbtn for laptop lid open/close events)?  Is it
       properly connected to a script (e.g. /etc/acpi/  Is that script
       working?  It's not unusual for an acpid script to check and see if
       there is a window manager running, then do nothing if there is.  This
       means it is up to the window manager to handle this event.

       acpid should work on any linux kernel released since 2003.


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

       regcomp(3) sh(1) socket(2) connect(2) init(1) systemd(1) acpi_listen(8)


       Ted Felix <>
       Tim Hockin <>
       Andrew Henroid