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28 .\" @(#)reboot.8 8.1 (Berkeley) 6/9/93
39 .Nd stopping and restarting the system
58 utilities flush the file system cache to disk, send all running processes
63 and, respectively, halt or restart the system.
64 The action is logged, including entering a shutdown record into the user
67 The options are as follows:
68 .Bl -tag -width indent
70 The system will turn off the power and then turn it back on if it can.
71 If the power down action fails, the system
72 will halt or reboot normally, depending on whether
77 At the present time, only the
79 driver implements the power cycle functionality and only on hardware
80 with a BMC that supports power cycling.
81 Unlike power off, the amount of hardware that supports power cycling
84 The system is requested to create a crash dump.
86 supported only when rebooting, and it has no effect unless a dump
87 device has previously been specified with
92 on the next system boot.
93 If the kernel boots successfully, the
95 kernel will be booted on successive boots, this is a one-shot option.
96 If the boot fails, the system will continue attempting to boot
98 until the boot process is interrupted and a valid kernel booted.
99 This may change in the future.
101 The halt or reboot is
103 logged to the system log.
104 This option is intended for applications such as
110 and log this themselves.
112 The file system cache is not flushed during the initial process clean-up,
113 however the kernel level
115 is still processed with a sync.
116 This option can be useful for performing a
118 reboot when devices might be unavailable.
119 This can happen when devices have been disconnected, such as with
122 The file system cache is not flushed.
123 This option should probably not be used.
125 The system will turn off the power if it can.
126 If the power down action fails, the system
127 will halt or reboot normally, depending on whether
133 The system is halted or restarted quickly and ungracefully, and only
134 the flushing of the file system cache is performed (if the
136 option is not specified).
137 This option should probably not be used.
139 The system kills all processes, unmounts all filesystems, mounts the new
140 root filesystem, and begins the usual startup sequence.
141 After changing vfs.root.mountfrom with
144 can be used to change the root filesystem while preserving kernel state.
147 kernel module to be loaded because
149 needs a place to store itself after the old root is unmounted, but
150 before the new root is in place.
157 utilities are nothing more than aliases for the
165 utility is used when the system needs to be halted or restarted, giving
166 users advance warning of their impending doom and cleanly terminating
169 Replace current root filesystem with UFS mounted from
171 .Bd -literal -offset indent
172 kenv vfs.root.mountfrom=ufs:/dev/ada0s1a
176 This mechanism can also be used with NFS, with a caveat that
177 it only works with NFSv4, and requires a numeric IPv4 address:
178 .Bd -literal -offset indent
179 kenv vfs.root.mountfrom=nfs:192.168.1.1:/share/name