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.Dd March 29, 2022 26.Dt NEXTBOOT 8 27.Os 28.Sh NAME 29.Nm nextboot 30.Nd "specify an alternate kernel and boot flags for the next reboot" 31.Sh SYNOPSIS 32.Nm 33.Op Fl af 34.Op Fl e Ar variable=value 35.Op Fl k Ar kernel 36.Op Fl o Ar options 37.Nm 38.Fl D 39.Sh DESCRIPTION 40The 41.Nm 42utility allows specifying some combination of an alternate kernel, boot 43flags, and kernel environment for the next time the machine is booted. 44Once the 45.Xr loader 8 46loads in the new kernel information from the 47.Pa /boot/nextboot.conf 48file, it is disabled so in case the new kernel hangs the machine, once 49it is rebooted, the machine will automatically revert to its previous 50configuration. 51.Pp 52The options are as follows: 53.Bl -tag -width ".Fl o Ar options" 54.It Fl a 55This option causes 56.Nm 57to append to an existing configuration in 58.Pa /boot/nextboot.conf . 59By default any existing configuration is overwritten. 60.It Fl D 61Invoking 62.Nm 63with this 64option removes an existing 65.Nm 66configuration. 67.It Fl e Ar variable=value 68This option adds the provided variable and value to the kernel environment. 69The value is quoted when written to the 70.Nm 71configuration. 72.It Fl f 73This 74option disables the sanity checking which checks if the kernel really exists 75before writing the 76.Nm 77configuration. 78.It Fl k Ar kernel 79This option specifies a kernel directory relative to 80.Pa /boot 81to load the kernel and any modules from. 82.It Fl o Ar options 83This option 84allows the passing of kernel flags for the next boot. 85.El 86.Sh FILES 87.Bl -tag -width ".Pa /boot/nextboot.conf" -compact 88.It Pa /boot/nextboot.conf 89The configuration file that the 90.Nm 91configuration is written into. 92.El 93.Sh EXAMPLES 94To boot the 95.Pa GENERIC 96kernel with the 97.Nm 98command: 99.Pp 100.Dl "nextboot -k GENERIC" 101.Pp 102To enable into single user mode with the normal kernel: 103.Pp 104.Dl "nextboot -o ""-s"" -k kernel" 105.Pp 106To remove an existing nextboot configuration: 107.Pp 108.Dl "nextboot -D" 109.Sh SEE ALSO 110.Xr boot 8 , 111.Xr freebsd-update 8 , 112.Xr loader 8 113.Sh HISTORY 114The original 115.Nm 116manual page first appeared in 117.Fx 2.2 . 118It used a very different interface to achieve similar results. 119.Pp 120The current incarnation of 121.Nm 122appeared in 123.Fx 5.0 . 124.Sh AUTHORS 125This manual page was written by 126.An Gordon Tetlow Aq Mt gordon@FreeBSD.org . 127.Sh BUGS 128The 129.Nm 130code is implemented in the 131.Xr loader 8 . 132It is not the most thoroughly tested code. 133It is also my first attempt to write in Forth. 134.Pp 135Finally, it does some evil things like writing to the file system before it 136has been checked. 137If it scrambles your file system, do not blame me. 138