Mask a unit

Mask symlinks a unit to /dev/null so it cannot start even as a dependency; stronger than disable

systemctl mask <unit> && systemctl unmask <unit>
tool
systemd26 commands
tags
systemdsecuritytroubleshooting

More systemd commands

  • Recursive dependency tree
    systemctl list-dependencies <unit> --all

    Walk the full Wants/Requires tree to debug why a service pulls in others; --reverse for who needs it

  • Live memory of a unit
    systemctl show -p MainPID,MemoryCurrent,TasksCurrent <unit>

    Read live cgroup metrics straight from systemd without ps; MemoryCurrent is the accounted RSS

  • Clear failed state
    systemctl reset-failed && systemctl list-units --state=failed

    Reset failed counters so units can restart past StartLimitBurst, then list what is still failed

  • Transient one-shot timer
    systemd-run --on-calendar='*-*-* 03:00:00' --unit=backup /usr/local/bin/backup.sh

    Spin up a throwaway timer+service without writing unit files; great for ad-hoc scheduled jobs

  • Runtime resource cap
    systemctl set-property --runtime <unit> MemoryMax=512M CPUQuota=50%

    Apply cgroup limits live without restart; --runtime keeps them volatile (gone on reboot)

all 26 systemd commands