1.\" Copyright (c) 2002 Gordon Tetlow 2.\" 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.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd March 17, 2015 28.Dt NEXTBOOT 8 29.Os 30.Sh NAME 31.Nm nextboot 32.Nd "specify an alternate kernel and boot flags for the next reboot" 33.Sh SYNOPSIS 34.Nm 35.Op Fl e Ar variable=value 36.Op Fl f 37.Op Fl k Ar kernel 38.Op Fl o Ar options 39.Nm 40.Fl D 41.Sh DESCRIPTION 42The 43.Nm 44utility allows specifying some combination of an alternate kernel, boot flags 45and kernel environment for the 46next time the machine is booted. 47Once the 48.Xr loader 8 49loads in the new kernel 50information, it is deleted so in case the new kernel hangs the machine, 51once it is rebooted, the machine will automatically revert to its previous 52configuration. 53.Pp 54The options are as follows: 55.Bl -tag -width ".Fl o Ar options" 56.It Fl D 57Invoking 58.Nm 59with this 60option removes an existing 61.Nm 62configuration. 63.It Fl e Ar variable=value 64This option adds the provided variable and value to the kernel environment. 65The value is quoted when written to the 66.Nm 67configuration. 68.It Fl f 69This 70option disables the sanity checking which checks if the kernel really exists 71before writing the 72.Nm 73configuration. 74.It Fl k Ar kernel 75This option specifies a kernel directory relative to 76.Pa /boot 77to load the kernel and any modules from. 78.It Fl o Ar options 79This option 80allows the passing of kernel flags for the next boot. 81.El 82.Sh FILES 83.Bl -tag -width ".Pa /boot/nextboot.conf" -compact 84.It Pa /boot/nextboot.conf 85The configuration file that the 86.Nm 87configuration is written into. 88.El 89.Sh EXAMPLES 90To boot the 91.Pa GENERIC 92kernel with the 93.Nm 94command: 95.Pp 96.Dl "nextboot -k GENERIC" 97.Pp 98To enable into single user mode with the normal kernel: 99.Pp 100.Dl "nextboot -o ""-s"" -k kernel" 101.Pp 102To remove an existing nextboot configuration: 103.Pp 104.Dl "nextboot -D" 105.Sh SEE ALSO 106.Xr boot 8 , 107.Xr loader 8 108.Sh HISTORY 109The original 110.Nm 111manual page first appeared in 112.Fx 2.2 . 113It used a very different interface to achieve similar results. 114.Pp 115The current incarnation of 116.Nm 117appeared in 118.Fx 5.0 . 119.Sh AUTHORS 120This manual page was written by 121.An Gordon Tetlow Aq Mt gordon@FreeBSD.org . 122.Sh BUGS 123The 124.Nm 125code is implemented in the 126.Xr loader 8 . 127It is not the most thoroughly tested code. 128It is also my first attempt to write in Forth. 129.Pp 130Finally, it does some evil things like writing to the file system before it 131has been checked. 132If it scrambles your file system, do not blame me. 133.Pp 134.Xr loader 8 135is only able to read ZFS, not write to it. 136.Pa nextboot.conf 137will NOT be reset in case of a kernel boot failure. 138