1.\" Copyright (c) 1988, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd August 4, 2024 29.Dt SHUTDOWN 8 30.Os 31.Sh NAME 32.Nm shutdown , 33.Nm poweroff 34.Nd "close down the system at a given time" 35.Sh SYNOPSIS 36.Nm 37.Op Fl 38.Oo 39.Fl c | Fl h | Fl p | 40.Fl r | Fl k 41.Oc 42.Oo 43.Fl o 44.Op Fl n 45.Oc 46.Op Fl q 47.Ar time 48.Op Ar warning-message ... 49.Nm poweroff 50.Sh DESCRIPTION 51The 52.Nm 53utility provides an automated shutdown procedure for super-users 54to nicely notify users when the system is shutting down, 55saving them from system administrators, hackers, and gurus, who 56would otherwise not bother with such niceties. 57In order to use the 58.Nm 59command, the user must have root privileges or be a member of the 60operator group. 61.Pp 62The following options are available: 63.Bl -tag -width indent 64.It Fl c 65The system is power cycled (power turned off and then back on) 66at the specified time. 67If the hardware doesn't support power cycle, the system will be 68rebooted. 69At the present time, only systems with BMC supported by the 70.Xr ipmi 4 71driver that implement this functionality support this flag. 72The amount of time the system is off is dependent on the device 73that implements this feature. 74.It Fl h 75The system is halted at the specified 76.Ar time . 77.It Fl p 78The system is halted and the power is turned off 79(hardware support required, otherwise the system is halted) 80at the specified 81.Ar time . 82.It Fl r 83The system is rebooted at the specified 84.Ar time . 85.It Fl k 86Kick everybody off. 87The 88.Fl k 89option 90does not actually halt the system, but leaves the 91system multi-user with logins disabled (for all but super-user). 92.It Fl o 93If one of the 94.Fl c , 95.Fl h , 96.Fl p 97or 98.Fl r 99options are specified, 100.Nm 101will execute 102.Xr halt 8 103or 104.Xr reboot 8 105instead of sending a signal to 106.Xr init 8 . 107.It Fl n 108If the 109.Fl o 110option is specified, prevent the file system cache from being flushed by passing 111.Fl n 112to 113.Xr halt 8 114or 115.Xr reboot 8 . 116This option should probably not be used. 117.It Fl q 118Shut down quietly. 119Suppress the warning message to all logged in users about system shutdown. 120It is an error to supply a 121.Ar warning-message 122when warnings are suppressed. 123.It Ar time 124.Ar Time 125is the time at which 126.Nm 127will bring the system down and 128may be the case-insensitive word 129.Ar now 130(indicating an immediate shutdown) or 131a future time in one of two formats: 132.Ar +number , 133or 134.Ar yymmddhhmm , 135where the year, month, and day may be defaulted 136to the current system values. 137The first form brings the system down in 138.Ar number 139minutes and the second at the absolute time specified. 140.Ar +number 141may be specified in units other than minutes by appending the corresponding 142suffix: 143.Dq Li s , 144.Dq Li sec , 145.Dq Li m , 146.Dq Li min , 147.Dq Li h , 148.Dq Li hour . 149.Pp 150If an absolute time is specified, but not a date, 151and that time today has already passed, 152.Nm 153will assume that the same time tomorrow was meant. 154(If a complete date is specified which has already passed, 155.Nm 156will print an error and exit without shutting the system down.) 157.It Ar warning-message 158Any other arguments comprise the warning message that is broadcast 159to users currently logged into the system. 160.It Fl 161If 162.Sq Fl 163is supplied as an option, the warning message is read from the standard 164input. 165.El 166.Pp 167At intervals, becoming more frequent as apocalypse approaches 168and starting at ten hours before shutdown, warning messages are displayed 169on the terminals of all users logged in. 170Five minutes before 171shutdown, or immediately if shutdown is in less than 5 minutes, 172logins are disabled by creating 173.Pa /var/run/nologin 174and copying the 175warning message there. 176If this file exists when a user attempts to 177log in, 178.Xr login 1 179prints its contents and exits. 180The file is 181removed just before 182.Nm 183exits. 184.Pp 185At shutdown time a message is written to the system log, containing the 186time of shutdown, the person who initiated the shutdown and the reason. 187The corresponding signal is then sent to 188.Xr init 8 189to respectively halt, reboot or bring the system down to single-user state 190(depending on the above options). 191The time of the shutdown and the warning message 192are placed in 193.Pa /var/run/nologin 194and should be used to 195inform the users about when the system will be back up 196and why it is going down (or anything else). 197.Pp 198A scheduled shutdown can be canceled by killing the 199.Nm 200process (a 201.Dv SIGTERM 202should suffice). 203The 204.Pa /var/run/nologin 205file that 206.Nm 207created will be removed automatically. 208.Pp 209When run without options, the 210.Nm 211utility will place the system into single user mode at the 212.Ar time 213specified. 214.Pp 215Calling 216.Dq Nm poweroff 217is equivalent to running: 218.Bd -literal -offset indent 219shutdown -p now 220.Ed 221.Sh FILES 222.Bl -tag -width /var/run/nologin -compact 223.It Pa /var/run/nologin 224tells 225.Xr login 1 226not to let anyone log in 227.El 228.Sh EXAMPLES 229Reboot the system in 30 minutes and display a warning message on the terminals 230of all users currently logged in: 231.Pp 232.Dl # shutdown -r +30 \&"System will reboot\&" 233.Sh COMPATIBILITY 234The hours and minutes in the second time format may be separated by 235a colon (``:'') for backward compatibility. 236.Sh SEE ALSO 237.Xr kill 1 , 238.Xr login 1 , 239.Xr wall 1 , 240.Xr nologin 5 , 241.Xr halt 8 , 242.Xr init 8 , 243.Xr reboot 8 244.Sh HISTORY 245A 246.Nm 247command was originally written by Ian Johnstone for UNSW's modified 248.At "6th Edn" . 249It was modified and then incorporated in 250.Bx 4.1 . 251