1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Donn Seeley at Berkeley Software Design, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)init.8 8.3 (Berkeley) 4/18/94 36.\" $FreeBSD: src/sbin/init/init.8,v 1.22.2.11 2003/05/03 22:19:20 keramida Exp $ 37.\" $DragonFly: src/sbin/init/init.8,v 1.6 2008/05/09 20:31:04 swildner Exp $ 38.\" 39.Dd April 18, 1994 40.Dt INIT 8 41.Os 42.Sh NAME 43.Nm init 44.Nd process control initialization 45.Sh SYNOPSIS 46.Nm 47.Nm 48.Oo 49.Cm 0 | 1 | 6 | 50.Cm c | q 51.Oc 52.Sh DESCRIPTION 53The 54.Nm 55utility 56is the last stage of the boot process. 57It normally runs the automatic reboot sequence as described in 58.Xr rc 8 , 59and if this succeeds, begins multi-user operation. 60If the reboot scripts fail, 61.Nm 62commences single-user operation by giving 63the super-user a shell on the console. 64The 65.Nm 66utility may be passed parameters 67from the boot program to 68prevent the system from going multi-user and to instead execute 69a single-user shell without starting the normal daemons. 70The system is then quiescent for maintenance work and may 71later be made to go to multi-user by exiting the 72single-user shell (with ^D). 73This 74causes 75.Nm 76to run the 77.Pa /etc/rc 78start up command file in fastboot mode (skipping disk checks). 79.Pp 80If the 81.Em console 82entry in the 83.Xr ttys 5 84file is marked 85.Dq insecure , 86then 87.Nm 88will require that the super-user password be 89entered before the system will start a single-user shell. 90The password check is skipped if the 91.Em console 92is marked as 93.Dq secure . 94.Pp 95The kernel runs with five different levels of security. 96Any super-user process can raise the security level, but no process 97can lower it. 98The security levels are: 99.Bl -tag -width flag 100.It Ic -1 101Permanently insecure mode \- always run the system in level 0 mode. 102This is the default initial value. 103.It Ic 0 104Insecure mode \- immutable and append-only flags may be turned off. 105All devices may be read or written subject to their permissions. 106.It Ic 1 107Secure mode \- the system immutable and system append-only flags may not 108be turned off; 109disks for mounted file systems, 110.Pa /dev/mem , 111and 112.Pa /dev/kmem 113may not be opened for writing; 114kernel modules (see 115.Xr kld 4 ) 116may not be loaded or unloaded. 117.It Ic 2 118Highly secure mode \- same as secure mode, plus disks may not be 119opened for writing (except by 120.Xr mount 2 ) 121whether mounted or not. 122This level precludes tampering with file systems by unmounting them, 123but also inhibits running 124.Xr newfs 8 125while the system is multi-user. 126.Pp 127In addition, kernel time changes are restricted to less than or equal to one 128second. Attempts to change the time by more than this will log the message 129.Dq Time adjustment clamped to +1 second . 130.It Ic 3 131Network secure mode \- same as highly secure mode, plus 132IP packet filter rules (see 133.Xr ipfw 8 134and 135.Xr ipfirewall 4 ) 136cannot be changed and 137.Xr dummynet 4 138configuration cannot be adjusted. 139.El 140.Pp 141If the security level is initially nonzero, then 142.Nm 143leaves it unchanged. 144Otherwise, 145.Nm 146raises the level to 1 before going multi-user for the first time. 147Since the level cannot be reduced, it will be at least 1 for 148subsequent operation, even on return to single-user. 149If a level higher than 1 is desired while running multi-user, 150it can be set before going multi-user, e.g., by the startup script 151.Xr rc 8 , 152using 153.Xr sysctl 8 154to set the 155.Va kern.securelevel 156variable to the required security level. 157.Pp 158In multi-user operation, 159.Nm 160maintains 161processes for the terminal ports found in the file 162.Xr ttys 5 . 163The 164.Nm 165utility reads this file and executes the command found in the second field, 166unless the first field refers to a device in 167.Pa /dev 168which is not configured. 169The first field is supplied as the final argument to the command. 170This command is usually 171.Xr getty 8 ; 172.Nm getty 173opens and initializes the tty line 174and 175executes the 176.Xr login 1 177program. 178The 179.Nm login 180program, when a valid user logs in, 181executes a shell for that user. When this shell 182dies, either because the user logged out 183or an abnormal termination occurred (a signal), 184the 185.Nm 186utility wakes up, deletes the user 187from the 188.Xr utmp 5 189file of current users and records the logout in the 190.Xr wtmp 5 191file. 192The cycle is 193then restarted by 194.Nm 195executing a new 196.Nm getty 197for the line. 198.Pp 199The 200.Nm 201utility can also be used to keep arbitrary daemons running, 202automatically restarting them if they die. 203In this case, the first field in the 204.Xr ttys 5 205file must not reference the path to a configured device node 206and will be passed to the daemon 207as the final argument on its command line. 208This is similar to the facility offered in the 209.At V 210.Pa /etc/inittab . 211.Pp 212Line status (on, off, secure, getty, or window information) 213may be changed in the 214.Xr ttys 5 215file without a reboot by sending the signal 216.Dv SIGHUP 217to 218.Nm 219with the command 220.Dq Li "kill -HUP 1" . 221On receipt of this signal, 222.Nm 223re-reads the 224.Xr ttys 5 225file. 226When a line is turned off in 227.Xr ttys 5 , 228.Nm 229will send a 230.Dv SIGHUP 231signal to the controlling process for the session associated with the line. 232For any lines that were previously turned off in the 233.Xr ttys 5 234file and are now on, 235.Nm 236executes the command specified in the second field. 237If the command or window field for a line is changed, 238the change takes effect at the end of the current 239login session (e.g., the next time 240.Nm 241starts a process on the line). 242If a line is commented out or deleted from 243.Xr ttys 5 , 244.Nm 245will not do anything at all to that line. 246However, it will complain that the relationship between lines 247in the 248.Xr ttys 5 249file and records in the 250.Xr utmp 5 251file is out of sync, 252so this practice is not recommended. 253.Pp 254The 255.Nm 256utility will terminate multi-user operations and resume single-user mode 257if sent a terminate 258.Pq Dv TERM 259signal, for example, 260.Dq Li "kill \-TERM 1" . 261If there are processes outstanding that are deadlocked (because of 262hardware or software failure), 263.Nm 264will not wait for them all to die (which might take forever), but 265will time out after 30 seconds and print a warning message. 266.Pp 267The 268.Nm 269utility will cease creating new processes 270and allow the system to slowly die away, if it is sent a terminal stop 271.Pq Dv TSTP 272signal, i.e.\& 273.Dq Li "kill \-TSTP 1" . 274A later hangup will resume full 275multi-user operations, or a terminate will start a single-user shell. 276This hook is used by 277.Xr reboot 8 278and 279.Xr halt 8 . 280.Pp 281The 282.Nm 283utility will terminate all possible processes (again, it will not wait 284for deadlocked processes) and reboot the machine if sent the interrupt 285.Pq Dv INT 286signal, i.e.\& 287.Dq Li "kill \-INT 1". 288This is useful for shutting the machine down cleanly from inside the kernel 289or from X when the machine appears to be hung. 290.Pp 291The 292.Nm 293utility will do the same, except it will halt the machine if sent 294the user defined signal 1 295.Pq Dv USR1 , 296or will halt and turn the power off (if hardware permits) if sent 297the user defined signal 2 298.Pq Dv USR2 . 299.Pp 300When shutting down the machine, 301.Nm 302will try to run the 303.Pa /etc/rc.shutdown 304script. 305This script can be used to cleanly terminate specific programs such 306as 307.Nm innd 308(the InterNetNews server). 309.Pp 310The role of 311.Nm 312is so critical that if it dies, the system will reboot itself 313automatically. 314If, at bootstrap time, the 315.Nm 316process cannot be located, the system will panic with the message 317.Dq "panic: init died (signal %d, exit %d)" . 318.Pp 319If run as a user process as shown in the second synopsis line, 320.Nm 321will emulate 322.At V 323behavior, i.e. super-user can specify the desired 324.Em run-level 325on a command line, and 326.Nm 327will signal the original 328(PID 1) 329.Nm 330as follows: 331.Bl -column Run-level SIGTERM 332.It Sy "Run-level Signal Action" 333.It Cm 0 Ta Dv SIGUSR2 Ta "Halt and turn the power off" 334.It Cm 1 Ta Dv SIGTERM Ta "Go to single-user mode" 335.It Cm 6 Ta Dv SIGINT Ta "Reboot the machine" 336.It Cm c Ta Dv SIGTSTP Ta "Block further logins" 337.It Cm q Ta Dv SIGHUP Ta Rescan the 338.Xr ttys 5 339file 340.El 341.Sh FILES 342.Bl -tag -width /etc/rc.shutdown -compact 343.It Pa /dev/console 344system console device 345.It Pa /dev/tty* 346terminal ports found in 347.Xr ttys 5 348.It Pa /var/run/utmp 349record of current users on the system 350.It Pa /var/log/wtmp 351record of all logins and logouts 352.It Pa /etc/ttys 353the terminal initialization information file 354.It Pa /etc/rc 355system startup commands 356.It Pa /etc/rc.shutdown 357system shutdown commands 358.El 359.Sh DIAGNOSTICS 360.Bl -diag 361.It "getty repeating too quickly on port %s, sleeping." 362A process being started to service a line is exiting quickly 363each time it is started. 364This is often caused by a ringing or noisy terminal line. 365.Bf -emphasis 366Init will sleep for 30 seconds, 367then continue trying to start the process. 368.Ef 369.It "some processes would not die; ps axl advised." 370A process 371is hung and could not be killed when the system was shutting down. 372This condition is usually caused by a process 373that is stuck in a device driver because of 374a persistent device error condition. 375.El 376.Sh SEE ALSO 377.Xr kill 1 , 378.Xr login 1 , 379.Xr sh 1 , 380.Xr dummynet 4 , 381.Xr ipfirewall 4 , 382.Xr kld 4 , 383.Xr ttys 5 , 384.Xr crash 8 , 385.Xr getty 8 , 386.Xr halt 8 , 387.Xr ipfw 8 , 388.Xr rc 8 , 389.Xr reboot 8 , 390.Xr shutdown 8 , 391.Xr sysctl 8 392.Sh HISTORY 393An 394.Nm 395utility appeared in 396.At v6 . 397.Sh CAVEATS 398Systems without 399.Xr sysctl 8 400behave as though they have security level \-1. 401.Pp 402Setting the security level above 1 too early in the boot sequence can 403prevent 404.Xr fsck 8 405from repairing inconsistent file systems. The 406preferred location to set the security level is at the end of 407.Pa /etc/rc 408after all multi-user startup actions are complete. 409