Boot critical chain

Show the serialized dependency chain that actually delays boot; more honest than blame

systemd-analyze critical-chain <unit>
tool
systemd26 commands
tags
systemdperformancetroubleshooting

More systemd commands

  • Boot timeline SVG
    systemd-analyze plot > boot.svg

    Render full parallel boot timeline as an SVG to spot serialized stalls visually

  • Drop-in override
    systemctl edit <unit> # writes /etc/systemd/system/<unit>.d/override.conf

    Patch a unit via drop-in without touching the vendor file; use --full to fork the whole unit

  • Reload unit files
    systemctl daemon-reload

    Reload unit files after editing; note: required after manual edits or systemctl warns of stale config

  • Mask a unit
    systemctl mask <unit> && systemctl unmask <unit>

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

  • 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

all 26 systemd commands