Tag Archives: libvirt

Too good to #0004

systemd, the good parts: monotonic timers

When systemd makes you suffer because “run job every 10 minutes” is infinitely harder to specify than in crontab, remember there are monotonic timers in systemd that aren’t derived from wallclock time, or “Calendar Events” as they call it.

Run timer once 60 seconds after system startup, then every 10 minutes after the job finished:

# /etc/systemd/system/demo.timer
Description=demo monotonic timer


WantedBy=timers.target    # When in a system session
# WantedBy=default.target # When in a user session (~/.config/systemd, systemctl --user etc.)

Python: Use tabulate to format output in columns

#!/usr/bin/env python3
from tabulate import tabulate

data = [
	[ 'foo', 'bar', 'baz' ],
	[ 'spam', 'eggs', 'bacon' ]

headers = ['Eine', '2', 'Whatever']

print(tabulate(data, headers=headers, tablefmt='simple'))


$ ./tab.py 
Eine    2     Whatever
------  ----  ----------
foo     bar   baz
spam    eggs  bacon

virsh/libvirt, automate key presses

(* Updated to sleep 5 seconds after each keypress.)

for key in R E I S U B; do virsh send-key "${domain}" KEY_LEFTALT KEY_SYSRQ KEY_${key}; sleep 5; done