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.\" 4. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)init.8 8.3 (Berkeley) 4/18/94 32.\" $FreeBSD$ 33.\" 34.Dd April 18, 1994 35.Dt INIT 8 36.Os 37.Sh NAME 38.Nm init 39.Nd process control initialization 40.Sh SYNOPSIS 41.Nm 42.Nm 43.Oo 44.Cm 0 | 1 | 6 | 45.Cm c | q 46.Oc 47.Sh DESCRIPTION 48The 49.Nm 50utility 51is the last stage of the boot process. 52It normally runs the automatic reboot sequence as described in 53.Xr rc 8 , 54and if this succeeds, begins multi-user operation. 55If the reboot scripts fail, 56.Nm 57commences single-user operation by giving 58the super-user a shell on the console. 59The 60.Nm 61utility may be passed parameters 62from the boot program to 63prevent the system from going multi-user and to instead execute 64a single-user shell without starting the normal daemons. 65The system is then quiescent for maintenance work and may 66later be made to go to multi-user by exiting the 67single-user shell (with ^D). 68This 69causes 70.Nm 71to run the 72.Pa /etc/rc 73start up command file in fastboot mode (skipping disk checks). 74.Pp 75If the 76.Em console 77entry in the 78.Xr ttys 5 79file is marked 80.Dq insecure , 81then 82.Nm 83will require that the super-user password be 84entered before the system will start a single-user shell. 85The password check is skipped if the 86.Em console 87is marked as 88.Dq secure . 89.Pp 90The kernel runs with five different levels of security. 91Any super-user process can raise the security level, but no process 92can lower it. 93The security levels are: 94.Bl -tag -width flag 95.It Ic -1 96Permanently insecure mode \- always run the system in level 0 mode. 97This is the default initial value. 98.It Ic 0 99Insecure mode \- immutable and append-only flags may be turned off. 100All devices may be read or written subject to their permissions. 101.It Ic 1 102Secure mode \- the system immutable and system append-only flags may not 103be turned off; 104disks for mounted file systems, 105.Pa /dev/mem , 106.Pa /dev/kmem 107and 108.Pa /dev/io 109(if your platform has it) may not be opened for writing; 110kernel modules (see 111.Xr kld 4 ) 112may not be loaded or unloaded. 113.It Ic 2 114Highly secure mode \- same as secure mode, plus disks may not be 115opened for writing (except by 116.Xr mount 2 ) 117whether mounted or not. 118This level precludes tampering with file systems by unmounting them, 119but also inhibits running 120.Xr newfs 8 121while the system is multi-user. 122.Pp 123In addition, kernel time changes are restricted to less than or equal to one 124second. 125Attempts to change the time by more than this will log the message 126.Dq Time adjustment clamped to +1 second . 127.It Ic 3 128Network secure mode \- same as highly secure mode, plus 129IP packet filter rules (see 130.Xr ipfw 8 131and 132.Xr ipfirewall 4 ) 133cannot be changed and 134.Xr dummynet 4 135configuration cannot be adjusted. 136.El 137.Pp 138If the security level is initially nonzero, then 139.Nm 140leaves it unchanged. 141Otherwise, 142.Nm 143raises the level to 1 before going multi-user for the first time. 144Since the level cannot be reduced, it will be at least 1 for 145subsequent operation, even on return to single-user. 146If a level higher than 1 is desired while running multi-user, 147it can be set before going multi-user, e.g., by the startup script 148.Xr rc 8 , 149using 150.Xr sysctl 8 151to set the 152.Va kern.securelevel 153variable to the required security level. 154.Pp 155If 156.Nm 157is run in a jail, the security level of the 158.Dq host system 159will not be effected. 160Part of the information set up in the kernel to support a jail 161is a per-jail 162.Dq securelevel 163setting. 164This allows running a higher security level inside of a jail 165than that of the host system. 166See 167.Xr jail 8 168for more information about jails. 169.Pp 170In multi-user operation, 171.Nm 172maintains 173processes for the terminal ports found in the file 174.Xr ttys 5 . 175The 176.Nm 177utility reads this file and executes the command found in the second field, 178unless the first field refers to a device in 179.Pa /dev 180which is not configured. 181The first field is supplied as the final argument to the command. 182This command is usually 183.Xr getty 8 ; 184.Nm getty 185opens and initializes the tty line 186and 187executes the 188.Xr login 1 189program. 190The 191.Nm login 192program, when a valid user logs in, 193executes a shell for that user. 194When this shell 195dies, either because the user logged out 196or an abnormal termination occurred (a signal), 197the 198.Nm 199utility wakes up, deletes the user 200from the 201.Xr utmp 5 202file of current users and records the logout in the 203.Xr wtmp 5 204file. 205The cycle is 206then restarted by 207.Nm 208executing a new 209.Nm getty 210for the line. 211.Pp 212The 213.Nm 214utility can also be used to keep arbitrary daemons running, 215automatically restarting them if they die. 216In this case, the first field in the 217.Xr ttys 5 218file must not reference the path to a configured device node 219and will be passed to the daemon 220as the final argument on its command line. 221This is similar to the facility offered in the 222.At V 223.Pa /etc/inittab . 224.Pp 225Line status (on, off, secure, getty, or window information) 226may be changed in the 227.Xr ttys 5 228file without a reboot by sending the signal 229.Dv SIGHUP 230to 231.Nm 232with the command 233.Dq Li "kill -HUP 1" . 234On receipt of this signal, 235.Nm 236re-reads the 237.Xr ttys 5 238file. 239When a line is turned off in 240.Xr ttys 5 , 241.Nm 242will send a SIGHUP signal to the controlling process 243for the session associated with the line. 244For any lines that were previously turned off in the 245.Xr ttys 5 246file and are now on, 247.Nm 248executes the command specified in the second field. 249If the command or window field for a line is changed, 250the change takes effect at the end of the current 251login session (e.g., the next time 252.Nm 253starts a process on the line). 254If a line is commented out or deleted from 255.Xr ttys 5 , 256.Nm 257will not do anything at all to that line. 258However, it will complain that the relationship between lines 259in the 260.Xr ttys 5 261file and records in the 262.Xr utmp 5 263file is out of sync, 264so this practice is not recommended. 265.Pp 266The 267.Nm 268utility will terminate multi-user operations and resume single-user mode 269if sent a terminate 270.Pq Dv TERM 271signal, for example, 272.Dq Li "kill \-TERM 1" . 273If there are processes outstanding that are deadlocked (because of 274hardware or software failure), 275.Nm 276will not wait for them all to die (which might take forever), but 277will time out after 30 seconds and print a warning message. 278.Pp 279The 280.Nm 281utility will cease creating new processes 282and allow the system to slowly die away, if it is sent a terminal stop 283.Pq Dv TSTP 284signal, i.e.\& 285.Dq Li "kill \-TSTP 1" . 286A later hangup will resume full 287multi-user operations, or a terminate will start a single-user shell. 288This hook is used by 289.Xr reboot 8 290and 291.Xr halt 8 . 292.Pp 293The 294.Nm 295utility will terminate all possible processes (again, it will not wait 296for deadlocked processes) and reboot the machine if sent the interrupt 297.Pq Dv INT 298signal, i.e.\& 299.Dq Li "kill \-INT 1". 300This is useful for shutting the machine down cleanly from inside the kernel 301or from X when the machine appears to be hung. 302.Pp 303The 304.Nm 305utility will do the same, except it will halt the machine if sent 306the user defined signal 1 307.Pq Dv USR1 , 308or will halt and turn the power off (if hardware permits) if sent 309the user defined signal 2 310.Pq Dv USR2 . 311.Pp 312When shutting down the machine, 313.Nm 314will try to run the 315.Pa /etc/rc.shutdown 316script. 317This script can be used to cleanly terminate specific programs such 318as 319.Nm innd 320(the InterNetNews server). 321.Pp 322The role of 323.Nm 324is so critical that if it dies, the system will reboot itself 325automatically. 326If, at bootstrap time, the 327.Nm 328process cannot be located, the system will panic with the message 329.Dq "panic: init died (signal %d, exit %d)" . 330.Pp 331If run as a user process as shown in the second synopsis line, 332.Nm 333will emulate 334.At V 335behavior, i.e., super-user can specify the desired 336.Em run-level 337on a command line, and 338.Nm 339will signal the original 340(PID 1) 341.Nm 342as follows: 343.Bl -column Run-level SIGTERM 344.It Sy "Run-level Signal Action 345.It Cm 0 Ta Dv SIGUSR2 Ta "Halt and turn the power off" 346.It Cm 1 Ta Dv SIGTERM Ta "Go to single-user mode" 347.It Cm 6 Ta Dv SIGINT Ta "Reboot the machine" 348.It Cm c Ta Dv SIGTSTP Ta "Block further logins" 349.It Cm q Ta Dv SIGHUP Ta Rescan the 350.Xr ttys 5 351file 352.El 353.Sh DIAGNOSTICS 354.Bl -diag 355.It "getty repeating too quickly on port %s, sleeping." 356A process being started to service a line is exiting quickly 357each time it is started. 358This is often caused by a ringing or noisy terminal line. 359.Bf -emphasis 360Init will sleep for 30 seconds, 361then continue trying to start the process. 362.Ef 363.It "some processes would not die; ps axl advised." 364A process 365is hung and could not be killed when the system was shutting down. 366This condition is usually caused by a process 367that is stuck in a device driver because of 368a persistent device error condition. 369.El 370.Sh FILES 371.Bl -tag -width /etc/rc.shutdown -compact 372.It Pa /dev/console 373system console device 374.It Pa /dev/tty* 375terminal ports found in 376.Xr ttys 5 377.It Pa /var/run/utmp 378record of current users on the system 379.It Pa /var/log/wtmp 380record of all logins and logouts 381.It Pa /etc/ttys 382the terminal initialization information file 383.It Pa /etc/rc 384system startup commands 385.It Pa /etc/rc.shutdown 386system shutdown commands 387.El 388.Sh SEE ALSO 389.Xr kill 1 , 390.Xr login 1 , 391.Xr sh 1 , 392.Xr dummynet 4 , 393.Xr ipfirewall 4 , 394.Xr kld 4 , 395.Xr ttys 5 , 396.Xr crash 8 , 397.Xr getty 8 , 398.Xr halt 8 , 399.Xr ipfw 8 , 400.Xr jail 8 , 401.Xr rc 8 , 402.Xr reboot 8 , 403.Xr shutdown 8 , 404.Xr sysctl 8 405.Sh HISTORY 406An 407.Nm 408utility appeared in 409.At v6 . 410.Sh CAVEATS 411Systems without 412.Xr sysctl 8 413behave as though they have security level \-1. 414.Pp 415Setting the security level above 1 too early in the boot sequence can 416prevent 417.Xr fsck 8 418from repairing inconsistent file systems. 419The 420preferred location to set the security level is at the end of 421.Pa /etc/rc 422after all multi-user startup actions are complete. 423