Runlevels

Finit supports runlevels, but unlike other init systems runlevels are declared per service/run/task/sysv command. When booting up a system Finit pass through three phases:

1. Setting up the console, parsing any command line options, and other housekeeping tasks like mounting all filesystems, and calling fsck
2. Starting all run/task/services in runlevel S, then waiting for all services to have started, and all run/tasks to have completed
3. Go to runlevel 2, or whatever the user has set in the configuration

Available runlevels:

• S: bootStrap
• 1: Single user mode
• 2-5: traditional multi-user mode
• 6: reboot
• 7-9: multi-user mode (extra)
• 0: shutdown

Runlevel S (bootStrap), is for tasks supposed to run once at boot, and services like syslogd, which need to start early and run throughout the lifetime of your system.

Example:

task [S] /lib/console-setup/console-setup.sh
service [S12345] env:-/etc/default/rsyslog rsyslogd -n $RSYSLOGD_ARGS

When bootstrap has completed, Finit moves to runlevel 2. This can be changed in /etc/finit.conf using the runlevel N directive, or by a script running in runlevel S that calls, e.g., initctl runlevel 9. The latter is useful if startup scripts detect problems outside of Finit's control, e.g., critical services/devices missing or hardware problems.

Each runlevel must be allowed to "complete". Meaning, all services in runlevel S must have started and all run/tasks have been started and collected (exited). Finit waits 120 seconds for all run/tasks in S to complete before proceeding to 2.

Finit first stops everything that is not allowed to run in 2, and then brings up networking. Networking is expected to be available in all runlevels except: S, 1 (single user level), 6, and 0. Networking is enabled either by the network script directive, or if you have an /etc/network/interfaces file, Finit calls ifup -a -- at the very least the loopback interface is brought up.

Note

When moving from runlevel S to 2, all run/task/services that were constrained to runlevel S only are dropped from bookkeeping. So when reaching the prompt, initctl will not show these run/tasks. This is a safety mechanism to prevent bootstrap-only tasks from accidentally being run again. E.g., console-setup.sh above.

Runlevel Configuration

Syntax: runlevel <N>

The system runlevel to go to after bootstrap (S) has completed. N is the runlevel number 0-9, where 6 is reserved for reboot and 0 for halt. Completed in this context means all services have been started and all run/tasks have been started and collected.

It is recommended to keep runlevel 1 as single-user mode, because Finit disables networking in this mode.

Default: 2

Note

Only read and executed in runlevel S (bootstrap).

Networking

Syntax: network <PATH>

Script or program to bring up networking, with optional arguments.

Deprecated. We recommend using dedicated task/run stanzas per runlevel, or /etc/network/interfaces if you have a system with ifupdown, like Debian, Ubuntu, Linux Mint, or an embedded BusyBox system.

Note

Only read and executed in runlevel S (bootstrap).

System Hostname

Syntax: host <NAME>, or hostname <NAME>

Set system hostname to NAME, unless /etc/hostname exists in which case the contents of that file is used.

Deprecated. We recommend using /etc/hostname instead.

Note

Only read and executed in runlevel S (bootstrap).

Kernel Modules

Syntax: module <MODULE> [ARGS]

Load a kernel module, with optional arguments. Similar to insmod command line tool.

Deprecated, there is both a modules-load.so and a modprobe.so plugin that can handle module loading better. The former supports loading from /etc/modules-load.d/, the latter uses kernel modinfo to automatically load (or coldplug) every required module. For hotplug we recommend the BusyBox mdev tool, add to /etc/mdev.conf:

$MODALIAS=.*  root:root       0660    @modprobe -b "$MODALIAS"

Note

Only read and executed in runlevel S (bootstrap).

Resource Limits

Syntax: rlimit [hard|soft] RESOURCE <LIMIT|unlimited>

Set the hard or soft limit for a resource, or both if that argument is omitted. RESOURCE is the lower-case RLIMIT_ string constants from setrlimit(2), without prefix. E.g. to set RLIMIT_CPU, use cpu.

LIMIT is an integer that depends on the resource being modified, see the man page, or the kernel /proc/PID/limits file, for details. Finit versions before v3.1 used infinity for unlimited, which is still supported, albeit deprecated.

# No process is allowed more than 8MB of address space
rlimit hard as 8388608

# Core dumps may be arbitrarily large
rlimit soft core infinity

# CPU limit for all services, soft & hard = 10 sec
rlimit cpu 10

rlimit can be set globally, in /etc/finit.conf, or locally per each /etc/finit.d/*.conf read. I.e., a set of task/run/service stanzas can share the same rlimits if they are in the same .conf.

Miscellaneous Settings

Syntax: reboot-delay <0-60>

Optional delay at reboot (or shutdown or halt) to allow kernel filesystem threads to complete after calling sync(2) before rebooting. This applies primarily to filesystems that do not have a reboot notifier implemented. At the point of writing, the only known filesystems affected are: ubifs, jffs2.

Default: 0 (disabled)

When enabled (non-zero), this delay runs after file systems have been unmounted and the root filesystem has been remounted read-only, and sync(2) has been called, twice.

"On Linux, sync is only guaranteed to schedule the dirty blocks for writing; it can actually take a short time before all the blocks are finally written.