One of the easiest ways to stress test an embedded Linux system is to continuously reboot the system. Booting is a difficult activity for a Linux system (similar to waking up in the morning). The CPU is maxed out. There are a lot of things happening in parallel. Software is initializing. There is a lot of filesystem activity. Often, if there is an instability in the system (and especially the filesystem), continuously rebooting will expose it.
Now that we use systemd for most new systems, we need to run a simple script X seconds after the system boots to increment the boot count, and reboot. This is the classic domain of a shell script. However, for a simple task like this, it’s a little cumbersome to create a seperate shell script and then call this script from a systemd unit. The following is a way to embed the script directly in a systemd unit.
Put the following in: /lib/systemd/system/cycletest.service
[Unit] Description=Reboots unit after 30s [Service] StandardOutput=syslog+console ExecStart=/bin/sh -c "\ test -f /cycle-count || echo 0 > /cycle-count;\ echo 'starting cycletest';\ sleep 30;\ expr `cat /cycle-count` + 1 > /cycle-count;\ reboot;\ " [Install] WantedBy=multi-user.target
To install and start the script:
- systemctl –system daemon-reload
- systemctl enable cycletest.service (enable the service to start on reboot)
- systemctl start cycletest.service (start the service, should reboot in 30s)