66-userctl¶

66-userctl queries and controls what 66-userd tracks.

Interface¶

66-userctl [ -h ] [ -z ] [ -v verbosity ] command [ subcommand ] [ operands ]

66-userctl reads the persisted state of the daemon under /run/66/userd/ directly, and talks to the daemon over its socket only for power actions.

Exit codes¶

0 : success.
100 : wrong usage—bad argument, bad usage, or an operation refused because of the state of the caller.
111 : a system call failed, or the daemon is unreachable.

Options¶

-h, --help : print the help and exit. Available at every level, including on subcommands.
-z, --color : enable color. If 66-userctl is not launched from a terminal, color is automatically disabled and the option has no effect.
-v, --verbosity verbosity : set the verbosity level of the command, from 0 to 5.
- 0 : only print error messages.
- 1 : also print informative messages. This is the default.
- 2 : also print warning messages.
- 3 : also print tracing messages.
- 4 : also print the function name and line of the messages.
- 5 : also display the sequence of the current process function by function.

Commands¶

list¶

66-userctl list users
66-userctl list sessions

list users shows the tracked users: uid, login name, state (offline, opening, online, closing) and live session count.

list sessions shows the tracked sessions with their owning user and where they are attached.

status¶

66-userctl status users <id|name>
66-userctl status sessions <id>

status users accepts either a uid or a login name, and shows the user together with its sessions.

status sessions shows one session in full: id, uid, user, leader pid, seat, VT number, type, class, tty, display, remote flag, PAM service, remote user, remote host, state and creation timestamp.

access¶

66-userctl access list
66-userctl access allow <user>
66-userctl access deny <user>

Manages /etc/66/shutdown.allow, the whitelist of users permitted to power the machine off. The file is the one of 66—one username per line—and is shared with the rest of the 66 tooling.

allow and deny are root only; a non-root caller gets a user error. list is readable by anyone.

If the file does not exist at all, there is no whitelist restriction: the gate is simply not applied. Creating it with a single access allow therefore tightens the policy for everyone else—worth knowing before running it the first time.

Power actions¶

66-userctl poweroff [ -f ]
66-userctl reboot [ -f ]
66-userctl halt [ -f ]
66-userctl suspend [ -f ]
66-userctl hibernate [ -f ]

-f, --force : proceed even if other users are logged in.

These do not act on the hardware themselves. The request goes to the daemon which, if the policy allows it, dispatches 66-hpr with the matching flag. poweroff, reboot and halt go through the fifo of 66-shutdownd; suspend and hibernate write /sys/power/state and block until resume. Success means the request was dispatched, not the machine has finished acting on it.

The policy is evaluated in this order:

root is always allowed—no further check.
Otherwise the caller must have an active local session. A purely remote caller—an ssh login with no local session—is refused with no active local session.
Then, if /etc/66/shutdown.allow exists, the caller must be listed in it. Refused with not authorized to power off.
Finally, if another user has an active session, --force is required. Refused with other users are logged in (use --force).

This is the one operation the daemon accepts from a non-root peer; REGISTER and RELEASE are root-only.

Notes¶

list and status never contact the daemon. They read the serialized records under /run/66/userd/sessions/ and /run/66/userd/users/, so they work—and show the last known state—even while the daemon is stopped. What they cannot do in that situation is tell you that the state is stale.

An empty list sessions on a system where users are clearly logged in almost always means the PAM module is not wired into the login stack. See pam_userd.