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 November 7, 2022 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.Ar time 47.Op Ar warning-message ... 48.Nm poweroff 49.Sh DESCRIPTION 50The 51.Nm 52utility provides an automated shutdown procedure for super-users 53to nicely notify users when the system is shutting down, 54saving them from system administrators, hackers, and gurus, who 55would otherwise not bother with such niceties. 56In order to use the 57.Nm 58command, the user must have root privileges or be a member of the 59operator group. 60.Pp 61The following options are available: 62.Bl -tag -width indent 63.It Fl c 64The system is power cycled (power turned off and then back on) 65at the specified time. 66If the hardware doesn't support power cycle, the system will be 67rebooted. 68At the present time, only systems with BMC supported by the 69.Xr ipmi 4 70driver that implement this functionality support this flag. 71The amount of time the system is off is dependent on the device 72that implements this feature. 73.It Fl h 74The system is halted at the specified 75.Ar time . 76.It Fl p 77The system is halted and the power is turned off 78(hardware support required, otherwise the system is halted) 79at the specified 80.Ar time . 81.It Fl r 82The system is rebooted at the specified 83.Ar time . 84.It Fl k 85Kick everybody off. 86The 87.Fl k 88option 89does not actually halt the system, but leaves the 90system multi-user with logins disabled (for all but super-user). 91.It Fl o 92If one of the 93.Fl c , 94.Fl h , 95.Fl p 96or 97.Fl r 98options are specified, 99.Nm 100will execute 101.Xr halt 8 102or 103.Xr reboot 8 104instead of sending a signal to 105.Xr init 8 . 106.It Fl n 107If the 108.Fl o 109option is specified, prevent the file system cache from being flushed by passing 110.Fl n 111to 112.Xr halt 8 113or 114.Xr reboot 8 . 115This option should probably not be used. 116.It Ar time 117.Ar Time 118is the time at which 119.Nm 120will bring the system down and 121may be the case-insensitive word 122.Ar now 123(indicating an immediate shutdown) or 124a future time in one of two formats: 125.Ar +number , 126or 127.Ar yymmddhhmm , 128where the year, month, and day may be defaulted 129to the current system values. 130The first form brings the system down in 131.Ar number 132minutes and the second at the absolute time specified. 133.Ar +number 134may be specified in units other than minutes by appending the corresponding 135suffix: 136.Dq Li s , 137.Dq Li sec , 138.Dq Li m , 139.Dq Li min , 140.Dq Li h , 141.Dq Li hour . 142.Pp 143If an absolute time is specified, but not a date, 144and that time today has already passed, 145.Nm 146will assume that the same time tomorrow was meant. 147(If a complete date is specified which has already passed, 148.Nm 149will print an error and exit without shutting the system down.) 150.It Ar warning-message 151Any other arguments comprise the warning message that is broadcast 152to users currently logged into the system. 153.It Fl 154If 155.Sq Fl 156is supplied as an option, the warning message is read from the standard 157input. 158.El 159.Pp 160At intervals, becoming more frequent as apocalypse approaches 161and starting at ten hours before shutdown, warning messages are displayed 162on the terminals of all users logged in. 163Five minutes before 164shutdown, or immediately if shutdown is in less than 5 minutes, 165logins are disabled by creating 166.Pa /var/run/nologin 167and copying the 168warning message there. 169If this file exists when a user attempts to 170log in, 171.Xr login 1 172prints its contents and exits. 173The file is 174removed just before 175.Nm 176exits. 177.Pp 178At shutdown time a message is written to the system log, containing the 179time of shutdown, the person who initiated the shutdown and the reason. 180The corresponding signal is then sent to 181.Xr init 8 182to respectively halt, reboot or bring the system down to single-user state 183(depending on the above options). 184The time of the shutdown and the warning message 185are placed in 186.Pa /var/run/nologin 187and should be used to 188inform the users about when the system will be back up 189and why it is going down (or anything else). 190.Pp 191A scheduled shutdown can be canceled by killing the 192.Nm 193process (a 194.Dv SIGTERM 195should suffice). 196The 197.Pa /var/run/nologin 198file that 199.Nm 200created will be removed automatically. 201.Pp 202When run without options, the 203.Nm 204utility will place the system into single user mode at the 205.Ar time 206specified. 207.Pp 208Calling 209.Dq Nm poweroff 210is equivalent to running: 211.Bd -literal -offset indent 212shutdown -p now 213.Ed 214.Sh FILES 215.Bl -tag -width /var/run/nologin -compact 216.It Pa /var/run/nologin 217tells 218.Xr login 1 219not to let anyone log in 220.El 221.Sh EXAMPLES 222Reboot the system in 30 minutes and display a warning message on the terminals 223of all users currently logged in: 224.Pp 225.Dl # shutdown -r +30 \&"System will reboot\&" 226.Sh COMPATIBILITY 227The hours and minutes in the second time format may be separated by 228a colon (``:'') for backward compatibility. 229.Sh SEE ALSO 230.Xr kill 1 , 231.Xr login 1 , 232.Xr wall 1 , 233.Xr nologin 5 , 234.Xr halt 8 , 235.Xr init 8 , 236.Xr reboot 8 237.Sh HISTORY 238A 239.Nm 240command was originally written by Ian Johnstone for UNSW's modified 241.At "6th Edn" . 242It was modified and then incorporated in 243.Bx 4.1 . 244