Introduction to acpid
The acpid (Advanced Configuration and Power
Interface event daemon) is a completely flexible, totally extensible
daemon for delivering ACPI events. It listens on netlink interface and
when an event occurs, executes programs to handle the event. The programs
it executes are configured through a set of configuration files, which can
be dropped into place by packages or by the user.
![[Note]](../images/note.png)
Note
Some other packages may handle some ACPI events as well and they
may conflict with this package. For example,
Systemd-254
(read the documentation for Handle*= in
logind.conf(5) for details) and
UPower-1.90.2 (used by many desktop environments such as
GNOME, KDE, and XFCE for handling ACPI events). If you've installed
such a package and it's enough for your use case, this package is
probably not needed. If you really need this package, you must be
careful configuring it and the other packages handling ACPI events
to avoid conflicts. Notably,
Systemd-254 handles some ACPI events
by default, so the handling of these events by
Systemd-254 should be
disabled first if handling these events with acpid
(again, read logind.conf(5) for details).
Note
Development versions of BLFS may not build or run
some packages properly if LFS or dependencies have been updated
since the most recent stable versions of the books.
Package Information
Installation of acpid
Install acpid by
running the following commands:
./configure --prefix=/usr \
--docdir=/usr/share/doc/acpid-2.0.34 &&
make
This package does not come with a test suite.
Now, as the root user:
make install &&
install -v -m755 -d /etc/acpi/events &&
cp -r samples /usr/share/doc/acpid-2.0.34
Configuring acpid
acpid is configured by user defined events.
Place event files under
/etc/acpi/events directory. If an
event occurs, acpid recurses through the event files in
order to see if the regex defined after "event" matches. If they do,
action is executed.
The following brief example will suspend the system when the laptop
lid is closed. The example also disables
the default handling of the lid close event by
Systemd-254 when the
system is on battery and not connected to any external monitor,
in order to avoid a conflict:
cat > /etc/acpi/events/lid << "EOF"
event=button/lid
action=/etc/acpi/lid.sh
EOF
cat > /etc/acpi/lid.sh << "EOF"
#!/bin/sh
/bin/grep -q open /proc/acpi/button/lid/LID/state && exit 0
/usr/bin/systemctl suspend
EOF
chmod +x /etc/acpi/lid.sh
mkdir -pv /etc/systemd/logind.conf.d
echo HandleLidSwitch=ignore > /etc/systemd/logind.conf.d/acpi.conf
Unfortunately, not every computer labels ACPI events in the same way
(for example, the lid may be recognized as LID0
instead of LID).
To determine how your buttons are recognized, use the
acpi_listen tool. Also, look in the samples directory under /usr/share/doc/acpid-2.0.34
for more examples.
Systemd Socket
To start the acpid daemon at boot,
install the systemd unit from the blfs-systemd-units-20230816
package by running the following command as the
root user:
make install-acpid
Note
This package uses socket based activation and will be started when
something needs it. No standalone unit file is provided for this
package.