Provided by: acpid_2.0.10-1ubuntu3_amd64 bug


       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

       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

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


       -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

       -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.

       -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

       -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 options.

       -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), kacpimon(8)


       Ted Felix (
       Tim Hockin <>
       Andrew Henroid