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 default).

       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)).
       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.

       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

       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.

       -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.  If the
                   debug level is non-zero, acpid will run in the foreground,
                   and will log to stderr, in addition to the regular syslog.

       -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

       -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/

       -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 following:

              /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 should work on any linux kernel released since 2003.


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

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

       Ted Felix (
       Tim Hockin <>
       Andrew Henroid