The command systemctl list-timers shows all active systemd timers, which are units that can be used to schedule the execution of other units at specific times or after certain intervals. The output of the command includes the following columns:
NEXT: The next time the timer will trigger.
LEFT: The time left until the next trigger.
LAST: The last time the timer triggered.
PASSED: The time passed since the last trigger.
UNIT: The name of the timer unit.
ACTIVATES: The name of the unit that is activated by the timer.
For example, the following output shows two active timers: apt-daily.timer and apt-daily-upgrade.timer, which are used to perform automatic updates on Debian-based systems.
NEXT LEFT LAST PASSED UNIT ACTIVATES Mon 2021-11-15 06:00:00 UTC 9h left Sun 2021-11-14 06:00:01 UTC 20h ago apt-daily.timer apt-daily.service Mon 2021-11-15 06:23:51 UTC 9h left Sun 2021-11-14 06:23:51 UTC 20h ago apt-daily-upgrade.timer apt-daily-upgrade.service 2 timers listed.
The other commands in the options are either invalid or unrelated to systemd timers:
systemctl-timer show is not a valid command. To show the details of a specific timer unit, the command systemctl show unit.timer can be used, where unit is the name of the unit that is activated by the timer.
timectl list is not a valid command. To list the available time zones, the command timedatectl list-timezones can be used. To list the current time and date settings, the command timedatectl can be used without any arguments.
systemctl -t is not a complete command. To list all units of a specific type, the command systemctl -t type can be used, where type is the name of the unit type, such as service, timer, socket, etc.
timeq is not a valid command. It may be confused with the time command, which measures the time taken by a command or program to execute.
References:
LPIC-1 Exam 102 Objectives, Topic 107: Administrative Tasks, Subtopic 107.2: Automate system administration tasks by scheduling jobs, Weight: 4, Key Knowledge Areas: Use cron and systemd timers to run jobs at regular intervals and to use anacron to manage system cron jobs. Objective: Use systemd timers to run jobs at regular intervals and to use anacron to manage system cron jobs.
LPIC-1 Exam 102 Learning Materials, Topic 107: Administrative Tasks, Subtopic 107.2: Automate system administration tasks by scheduling jobs, Section 107.2.3: systemd timers, Page 21-22.
