upslog - UPS status logger

upslog -h

upslog [OPTIONS]

upslog is a daemon that will poll a UPS at periodic intervals, fetch the variables that interest you, format them, and write them to a file.

The default format string includes variables that are supported by many common UPS models. See the description below to make your own.


Display the help message.

-f format

Monitor the UPS using this format string. Be sure to enclose format in quotes so your shell doesn’t split it up. Valid escapes within this string are:


Insert a single "%"

%TIME format%

Insert the time with strftime formatting


Insert the number of seconds, ala time_t. This is now a 10 digit number.


insert the local hostname


insert the host of the UPS being monitored


insert the pid of upslog

%VAR varname%

insert the value of variable varname (see NUT developer documentation chapter "Variables" on-line or in the docs/nut-names.txt file in sources of the NUT version you have installed for more details)

The default format string is:

%TIME @Y@m@d @H@M@S% %VAR battery.charge% %VAR input.voltage%
%VAR ups.load% [%VAR ups.status%] %VAR ups.temperature%
%VAR input.frequency%

-i interval

Wait this many seconds between polls. This defaults to 30 seconds.

If you require tighter timing, you should write your own logger using the upsclient(3) library.

-l logfile

Store the results in this file.

You can use "-" for stdout, but upslog will remain in the foreground by default.


upslog will run in the foreground, regardless of logging target.


upslog will run in the background, regardless of logging target.

-s ups

Monitor this UPS. The format for this option is upsname[@hostname[:port]]. The default hostname is "localhost".

-m tuple

Monitor multiple UPSs. The format for this option is a tuple of ups and logfile separated by commas. An example would be: upsname@hostname:9999,/var/log/nut/cps.log

-u username

If started as root, upslog will setuid(2) to the user id associated with username for security.

If username is not defined, it will use the value that was compiled into the program. This defaults to "nobody", which is less than ideal.

The interval value is merely the number given to sleep(3) after running through the format string. Therefore, a query will actually take slightly longer than the interval, depending on the speed of your system.

Sending a USR1 signal to a running upslog process makes it wake from the current sleep and log immediately. This is useful when triggered from a upssched event trigger (e.g. AT ONBATT or AT ONLINE) to ensure that an entry always exists, even if the power goes away for a period of time shorter than that specified by the -i argument.

upslog writes its PID to, and will reopen the log file if you send it a SIGHUP. This allows it to keep running when the log is rotated by an external program.


upsc(8), upscmd(8), upsrw(8), upsmon(8), upssched(8)

The NUT (Network UPS Tools) home page:

05/20/2024 Network UPS Tools 2.8.2