shutdown.tproj/shutdown.8

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  32 .\"     @(#)shutdown.8  8.2 (Berkeley) 4/27/95
  33 .\" $FreeBSD: src/sbin/shutdown/shutdown.8,v 1.21 2002/12/23 16:04:50 ru Exp $
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  35 .Dd December 11, 1998
  36 .Dt SHUTDOWN 8
  37 .Os
  38 .Sh NAME
  39 .Nm shutdown
  40 .Nd "close down the system at a given time"
  41 .Sh SYNOPSIS
  42 .Nm
  43 .Op Fl
  44 .Oo
  45 .Fl h
  46 .Op Fl u
  47 |
  48 .Fl r | Fl k
  49 .Oc
  50 .Oo
  51 .Fl o
  52 .Op Fl n
  53 .Oc
  54 .Ar time
  55 .Op Ar warning-message ...
  56 .Sh DESCRIPTION
  57 The
  58 .Nm
  59 utility provides an automated shutdown procedure for super-users
  60 to nicely notify users when the system is shutting down,
  61 saving them from system administrators, hackers, and gurus, who
  62 would otherwise not bother with such niceties.
  63 .Pp
  64 The following options are available:
  65 .Bl -tag -width indent
  66 .It Fl h
  67 The system is halted at the specified
  68 .Ar time .
  69 .It Fl r
  70 The system is rebooted at the specified
  71 .Ar time .
  72 .It Fl k
  73 Kick everybody off.
  74 The
  75 .Fl k
  76 option
  77 does not actually halt the system, but leaves the
  78 system multi-user with logins disabled (for all but super-user).
  79 .It Fl o
  80 If
  81 .Fl h
  82 or
  83 .Fl r
  84 is specified,
  85 .Nm
  86 will execute
  87 .Xr halt 8
  88 or
  89 .Xr reboot 8
  90 instead of sending signal to
  91 .Xr init 8 .
  92 .It Fl n
  93 If the
  94 .Fl o
  95 is specified, prevent the file system cache from being flushed by passing
  96 .Fl n
  97 option to
  98 .Xr halt 8
  99 or
 100 .Xr reboot 8 .
 101 This option should probably not be used.
 102 .It Fl u
 103 The system is halted up until the point of removing system power, but waits
 104 before removing power for 5 minutes so that an external UPS
 105 (uninterruptible power supply) can forcibly remove power.
 106 This simulates a dirty shutdown to permit a later automatic power on. OS X uses
 107 this mode automatically with supported UPSs in emergency shutdowns.
 108 .It Ar time
 109 .Ar Time
 110 is the time at which
 111 .Nm
 112 will bring the system down and
 113 may be the word
 114 .Ar now
 115 (indicating an immediate shutdown) or
 116 specify a future time in one of two formats:
 117 .Ar +number ,
 118 or
 119 .Ar yymmddhhmm ,
 120 where the year, month, and day may be defaulted
 121 to the current system values.  The first form brings the system down in
 122 .Ar number
 123 minutes and the second at the absolute time specified.
 124 .It Ar warning-message
 125 Any other arguments comprise the warning message that is broadcast
 126 to users currently logged into the system.
 127 .It Fl
 128 If
 129 .Sq Fl
 130 is supplied as an option, the warning message is read from the standard
 131 input.
 132 .El
 133 .Pp
 134 At intervals, becoming more frequent as apocalypse approaches
 135 and starting at ten hours before shutdown, warning messages are displayed
 136 on the terminals of all users logged in.  Five minutes before
 137 shutdown, or immediately if shutdown is in less than 5 minutes,
 138 logins are disabled by creating
 139 .Pa /var/run/nologin
 140 and copying the
 141 warning message there.  If this file exists when a user attempts to
 142 log in,
 143 .Xr login 1
 144 prints its contents and exits.  The file is
 145 removed just before
 146 .Nm
 147 exits.
 148 .Pp
 149 At shutdown time a message is written to the system log, containing the
 150 time of shutdown, the person who initiated the shutdown and the reason.
 151 Corresponding signal is then sent to
 152 .Xr init 8
 153 to respectively halt, reboot or bring the system down to single-user state
 154 (depending on the above options).
 155 The time of the shutdown and the warning message
 156 are placed in
 157 .Pa /var/run/nologin
 158 and should be used to
 159 inform the users about when the system will be back up
 160 and why it is going down (or anything else).
 161 .Pp
 162 A scheduled shutdown can be canceled by killing the
 163 .Nm
 164 process (a
 165 .Dv SIGTERM
 166 should suffice).
 167 The
 168 .Pa /var/run/nologin
 169 file that
 170 .Nm
 171 created will be removed automatically.
 172 .Sh FILES
 173 .Bl -tag -width /var/run/nologin -compact
 174 .It Pa /var/run/nologin
 175 tells login not to let anyone log in
 176 .El
 177 .Sh SEE ALSO
 178 .Xr kill 1 ,
 179 .Xr login 1 ,
 180 .Xr wall 1 ,
 181 .Xr nologin 5 ,
 182 .Xr halt 8 ,
 183 .Xr init 8 ,
 184 .Xr reboot 8
 185 .Sh BACKWARD COMPATIBILITY
 186 The hours and minutes in the second time format may be separated by
 187 a colon (``:'') for backward compatibility.
 188 .Sh HISTORY
 189 The
 190 .Nm
 191 utility appeared in
 192 .Bx 4.0 .