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-256.5 (read the documentation
for Handle*= in logind.conf(5)
for details) and UPower-1.90.6 (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-256.5 handles some ACPI events
by default, so the handling of these events by Systemd-256.5 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-256.5 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-20241211 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.