This document describes how to install the APC UPS daemon. The APC UPS can communicate with the Linux system through either a RS-232 or USB serial connection. In the event of a prolonged power outage, should the APC UPS lose most of its battery capacity, it can tell the Linux box to perform a safe shutdown.
Install the package
Install the package.
Configure APC UPS
The main configuration file for the APC UPS daemon can be found in
In the following example, the lines of text are changed to support a USB style cable:
UPSCABLE smart UPSTYPE smartups DEVICE /dev/ttyS0
UPSCABLE usb UPSTYPE usb # For USB UPSes, leave the DEVICE directive blank. DEVICE
First, enable and start
Next, wait about a minute and confirm the daemon is running and properly monitoring the battery:
# apcaccess status
APC : 001,033,0819 DATE : Sat Mar 05 SOMETIME 2005 HOSTNAME : somehostname RELEASE : 3.10.16 VERSION : 3.10.16 (04 November 2004) unknown UPSNAME : somehostname CABLE : USB Cable MODEL : Back-UPS ES 725 UPSMODE : Stand Alone STARTTIME: Sat Mar SOMETIME 2005 STATUS : ONLINE LINEV : 119.0 Volts LOADPCT : 23.0 Percent Load Capacity BCHARGE : 100.0 Percent TIMELEFT : 30.5 Minutes MBATTCHG : 5 Percent MINTIMEL : 3 Minutes MAXTIME : 0 Seconds LOTRANS : 088.0 Volts HITRANS : 138.0 Volts ALARMDEL : Always BATTV : 13.5 Volts NUMXFERS : 0 TONBATT : 0 seconds CUMONBATT: 0 seconds XOFFBATT : N/A STATFLAG : 0x02000008 Status Flag MANDATE : 2002-12-02 SERIALNO : QB0249360043 BATTDATE : 2000-00-00 NOMBATTV : 12.0 FIRMWARE : 02.n2.D USB FW:n2 APCMODEL : Back-UPS ES 725 END APC : Sat SOMETIME 2005
To fully test your setup:
- Remove wall power from the UPS.
- Observe that your Linux box powers down, in short order.
- Plug the UPS back into the wall.
- Power on your Linux box.
When everything is ok, all that is left to do is enable the
Hibernating instead of shutting down
You can make your system hibernate instead of shutting down. First, make sure the system hibernates cleanly. To set up hibernation, see Power management/Suspend and hibernate.
Create the hibernate script
Create this in
/usr/local/bin/hibernate as root:
#!/bin/bash # Hibernate the system - designed to be called via symlink from /etc/apcupsd # directory in case of apcupsd initiating a shutdown/reboot. Can also be used # interactively or from any script to cause a hibernate. # Do the hibernate /usr/bin/systemctl hibernate # At this point system should be hibernated - when it comes back, we resume this script here # On resume, tell controlling script (/etc/apcupsd/apccontrol) NOT to continue with default action (i.e. shutdown). exit 99
Make it executable by running:
# chmod +x /usr/local/bin/hibernate
Link the hibernate script for apcupsd to use it
Create a symbolic link from the
/etc/apcupsd directory to the script. The result is the apcupd's apccontrol script, in this directory, will call the hibernate script instead of doing the default shutdown action for these operations.
# ln -s /usr/local/bin/hibernate /etc/apcupsd/doshutdown
If you are running apcupsd as a client to another machine running apcupsd as a server and want your machine to hibernate if the sever is shutdown or if communication to the server is lost then you may also wish to add:
# ln -s /usr/local/bin/hibernate /etc/apcupsd/remotedown
Make apcupsd kill UPS power once the hibernate is done
Once the PC has hibernated successfully, it is common practice to switch off the UPS in order to conserve battery charge and prevent full battery drain. This can be achieved through a power suspend event in systemd.
/usr/lib/systemd/system-sleep/ups-kill and put the following contents in it:
#!/bin/bash case $2 in # In the event the computer is hibernating. hibernate) case $1 in # Going into a hibernate state. pre) # See if this is a powerfail situation. if [ -f /etc/apcupsd/powerfail ]; then echo echo "ACPUPSD will now power off the UPS" echo /etc/apcupsd/apccontrol killpower echo echo "Please ensure that the UPS has powered off before rebooting" echo "Otherwise, the UPS may cut the power during the reboot!!!" echo fi ;; # Coming out of a hibernate state. post) # If there are remnants from a powerfail situation, remove them. if [ -f /etc/apcupsd/powerfail ]; then rm /etc/apcupsd/powerfail fi # This may also exist, need to remove it. if [ -f /etc/nologin ]; then rm /etc/nologin fi # Restart the daemon; otherwise it may be unresponsive in a # second powerfailure situation. systemctl restart apcupsd ;; esac ;; esac
Make the script executable by doing:
# chmod +x /usr/lib/systemd/system-sleep/ups-kill
Now you can test your setup.
The desktop environment will also sense the UPS if connected by USB cable
For example, the default KDE setting is to put the computer in sleep if it has been on UPS battery for more than 10 minutes and the mouse has not moved. On many computers this causes a crash. This can be changed from KDE System Settings > Power Management > On battery.
hid-generic : control queue full
If you are using a systemd-based initramfs you might run into the "control queue full" log message happening many times every second. You will want to add
hid-generic to you
modules and regenerate your initramfs.