--- name: "init" section: "8" platform: "openbsd" package: "man" version: "8.0-current-20261101" release: "OpenBSD 8.0-current (2026-11-01)" platforms: ["linux", "freebsd", "openbsd"] url: "https://new.carta.tech/init/8" --- # init(8) process control initialization ## NAME **init** – process control initialization ## SYNOPSIS **init** \[**-fs**\] ## DESCRIPTION The **init** program is the last stage of the boot process. It normally executes the sequence of events described in [rc(8)](/rc/8.md) and begins multi-user operation. The kernel may pass the following options to **init**, usually when requested by the [boot(8)](/boot/8.md) program: - **-f** Activate fastboot mode. This is not currently supported by the OpenBSD kernel. Instead, use the */fastboot* file as explained in the [rc(8)](/rc/8.md) manual. - **-s** Boot directly into single-user mode. Single-user mode is also entered if the boot scripts fail. In single-user mode, the [rc(8)](/rc/8.md) script is not run and normal daemons are not started, but instead a super-user shell is started on the system console. If the *console* entry in the [ttys(5)](/ttys/5.md) file does not contain the “secure” flag, then **init** will require that the superuser password be entered before the system will start a single-user shell. The password check is skipped if the *console* is marked as “secure”. In single-user mode, the system is quiescent for maintenance work and may later be made to go to multi-user by exiting the single-user shell (with ^D). This causes **init** to run the [rc(8)](/rc/8.md) startup command file in fastboot mode (skipping disk checks). The kernel [securelevel(7)](/securelevel/7.md) is normally set to 0 while in single-user mode, and raised to 1 when the system begins multi-user operations. This action will not take place if the securelevel is -1, and can be modified via the */etc/rc.securelevel* script. In multi-user operation, **init** maintains processes for the terminal ports found in the file [ttys(5)](/ttys/5.md). **init** reads this file, and executes the command found in the second field. This command is usually [getty(8)](/getty/8.md); *getty* opens and initializes the tty line and executes the *login* program. The *login* program, when a valid user logs in, executes a shell for that user. When this shell dies, either because the user logged out or an abnormal termination occurred (a signal), the **init** program wakes up, deletes the user from the [utmp(5)](/utmp/5.md) file of current users and records the logout in the *wtmp* file. The cycle is then restarted by **init** executing a new *getty* for the line. Line status (on, off, secure, or getty command) may be changed in the *ttys* file without a reboot by sending the signal SIGHUP to **init** with the command “kill -s HUP 1”. On receipt of this signal, **init** re-reads the *ttys* file. When a line is turned off in *ttys*, **init** will send a SIGHUP signal to the controlling process for the session associated with the line. For any lines that were previously turned off in the *ttys* file and are now on, **init** executes a new *getty* to enable a new login. If the getty command for a line is changed, the change takes effect at the end of the current login session (e.g., the next time **init** starts a process on the line). If a line is commented out or deleted from *ttys*, **init** will not do anything at all to that line. However, it will complain that the relationship between lines in the *ttys* file and records in the *utmp* file is out of sync, so this practice is not recommended. **init** will terminate multi-user operations and resume single-user mode if sent a terminate (TERM) signal, for example, “kill -s TERM 1”. If there are processes outstanding that are deadlocked (because of hardware or software failure), **init** will not wait for them all to die (which might take forever), but will time out after 30 seconds and print a warning message. **init** will cease creating new [getty(8)](/getty/8.md) and allow the system to slowly die away, if it is sent a terminal stop (TSTP) signal, i.e., “kill -s TSTP 1”. A later hangup will resume full multi-user operations, or a terminate will start a single-user shell. This hook is used by [reboot(8)](/reboot/8.md) and [halt(8)](/halt/8.md). **init** will terminate multi-user operations, kill all [getty(8)](/getty/8.md), and run */etc/rc.shutdown* if a user-defined signal 1 (USR1), user-defined signal 2 (USR2), or interrupt (INT) signal is received. Following this, USR1 will halt the system; USR2 will request a powerdown; and INT will cause a reboot. */etc/rc.shutdown* can specify that a powerdown is requested instead of the action specified by the signal. The role of **init** is so critical that if it dies, the system will reboot itself automatically. If, at bootstrap time, the **init** process cannot be located, the system will panic with the message “panic: init died (signal %d, exit %d)”. ## RESOURCES When **init** spawns a process it sets the process priority, umask, and resource limits based on */etc/login.conf*. When starting the [rc(8)](/rc/8.md) files, the login class “daemon” is used. When starting a [getty(8)](/getty/8.md), the login class “default” is used. No resource changes are made when entering single-user mode. ## FILES - */dev/console* system console device - */dev/tty\** terminal ports found in *ttys* - */etc/rc* system startup commands - */etc/rc.securelevel* commands that run before the security level changes - */etc/rc.shutdown* script run at shutdown time - */etc/ttys* terminal initialization information file - */fastboot* tells [rc(8)](/rc/8.md) not to run [fsck(8)](/fsck/8.md) during the next boot - */var/run/utmp* record of users currently logged in - */var/log/wtmp* record of all logins and logouts ## DIAGNOSTICS - getty repeating too quickly on port %s, sleeping A process being started to service a line is exiting quickly each time it is started. This is often caused by a ringing or noisy terminal line. *Init will sleep for 30 seconds*, *then continue trying to start the process*. - some processes would not die; ps axl advised. A process is hung and could not be killed when the system was shutting down. This condition is usually caused by a process that is stuck in a device driver because of a persistent device error condition. ## SEE ALSO [kill(1)](/kill/1.md), [login(1)](/login/1.md), [sh(1)](/sh/1.md), [fbtab(5)](/fbtab/5.md), [login.conf(5)](/login.conf/5.md), [ttys(5)](/ttys/5.md), [securelevel(7)](/securelevel/7.md), [crash(8)](/crash/8.md), [getty(8)](/getty/8.md), [halt(8)](/halt/8.md), [rc(8)](/rc/8.md), [rc.shutdown(8)](/rc.shutdown/8.md), [reboot(8)](/reboot/8.md), [shutdown(8)](/shutdown/8.md) ## HISTORY An **init** command appeared in Version 1 AT&T UNIX.