The shutdown configuration in sysfs

Ubuntu 22.04 LTS LPAR mode z/VM guest KVM guest

The configured shutdown action for each shutdown trigger is stored in a sysfs attribute /sys/firmware/shutdown_actions/on_<trigger>.

This graphic shows the /sys/firmware/shutdown_actions directory with the contained attributes on_halt, on_poff, on_reboot, on_restart, and on_panic. — Figure 1. sysfs branch with shutdown action settings

The preferred way to read or change these settings is using the lsshut, chshut. For dump actions on Linux® in LPAR mode or Linux on z/VM®, the preferred way is the dumpconf command. Alternatively, you can read and write to the /sys/firmware/shutdown_actions/on_<trigger> attributes.

Examples

This command reads the shutdown setting for the poff shutdown trigger.
```
# cat /sys/firmware/shutdown_actions/on_poff
stop
```
This command changes the setting for the restart shutdown trigger to ipl:
```
# echo ipl > /sys/firmware/shutdown_actions/on_restart
```

Details for the ipl, reipl, dump, and vmcmd shutdown actions are contained in the corresponding subdirectories in /sys/firmware. For example, /sys/firmware/ipl contains specifications for an IPL device and other IPL parameters.