freebsd-dev/sys/boot/common/help.common
John-Mark Gurney 2fd290094e remove a pointless comment with a more helpful one...
Submitted by:	Tobias Roth
MFC after:	5 days
2005-07-25 17:18:25 +00:00

384 lines
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# Thelp DDisplay command help
help [topic [subtopic]]
help index
The help command displays help on commands and their usage.
In command help, a term enclosed with <...> indicates a value as
described by the term. A term enclosed with [...] is optional,
and may not be required by all forms of the command.
Some commands may not be available. Use the '?' command to list
most available commands.
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# T? DList available commands
?
Lists all available commands.
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# Tautoboot DBoot after a delay
autoboot [<delay> [<prompt>]]
Displays <prompt> or a default prompt, and counts down <delay> seconds
before attempting to boot. If <delay> is not specified, the default
value is 10.
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# Tboot DBoot immediately
boot [<kernelname>] [-<arg> ...]
Boot the system. If arguments are specified, they are added to the
arguments for the kernel. If <kernelname> is specified, and a kernel
has not already been loaded, it will be booted instead of the default
kernel.
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# Tbcachestat DGet disk block cache stats
bcachestat
Displays statistics about disk cache usage. For depuration only.
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# Techo DEcho arguments
echo [-n] [<message>]
Emits <message>, with no trailing newline if -n is specified. This is
most useful in conjunction with scripts and the '@' line prefix.
Variables are substituted by prefixing them with $, eg.
echo Current device is $currdev
will print the current device.
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# Tload DLoad a kernel or module
load [-t <type>] <filename>
Loads the module contained in <filename> into memory. If no other
modules are loaded, <filename> must be a kernel or the command will
fail.
If -t is specified, the module is loaded as raw data of <type>, for
later use by the kernel or other modules. <type> may be any string.
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# Tls DList files
ls [-l] [<path>]
Displays a listing of files in the directory <path>, or the root
directory of the current device if <path> is not specified.
The -l argument displays file sizes as well; the process of obtaining
file sizes on some media may be very slow.
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# Tlsdev DList devices
lsdev [-v]
List all of the devices from which it may be possible to load modules.
If -v is specified, print more details.
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# Tlsmod DList modules
lsmod [-v]
List loaded modules. If [-v] is specified, print more details.
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# Tmore DPage files
more <filename> [<filename> ...]
Show contents of text files. When displaying the contents of more,
than one file, if the user elects to quit displaying a file, the
remaining files will not be shown.
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# Tpnpscan DScan for PnP devices
pnpscan [-v]
Scan for Plug-and-Play devices. This command is normally automatically
run as part of the boot process, in order to dynamically load modules
required for system operation.
If the -v argument is specified, details on the devices found will
be printed.
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# Tset DSet a variable
set <variable name>
set <variable name>=<value>
The set command is used to set variables.
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# Tset Sautoboot_delay DSet the default autoboot delay
set autoboot_delay=<value>
Sets the default delay for the autoboot command to <value> seconds.
Set value to -1 if you don't want to allow user to interrupt autoboot
process and escape to the loader prompt.
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# Tset Sbootfile DSet the default boot file set
set bootfile=<filename>[;<filename>...]
Sets the default set of kernel boot filename(s). It may be overridden
by setting the bootfile variable to a semicolon-separated list of
filenames, each of which will be searched for in the module_path
directories. The default bootfile set is "kernel".
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# Tset Sboot_askname DPrompt for root device
set boot_askname
Instructs the kernel to prompt the user for the name of the root device
when the kernel is booted.
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# Tset Sboot_cdrom DMount root file system from CD-ROM
set boot_cdrom
Instructs the kernel to try to mount the root file system from CD-ROM.
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# Tset Sboot_ddb DDrop to the kernel debugger (DDB)
set boot_ddb
Instructs the kernel to start in the DDB debugger, rather than
proceeding to initialize when booted.
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# Tset Sboot_gdb DSelect gdb-remote mode for the kernel debugger
set boot_gdb
Selects gdb-remote mode for the kernel debugger by default.
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# Tset Sboot_multicons DUse multiple consoles
set boot_multicons
Enables multiple console support in the kernel early on boot.
In a running system, console configuration can be manipulated
by the conscontrol(8) utility.
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# Tset Sboot_serial DUse serial console
set boot_serial
Force the use of a serial console even when an internal console
is present.
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# Tset Sboot_single DStart system in single-user mode
set boot_single
Prevents the kernel from initiating a multi-user startup; instead,
a single-user mode will be entered when the kernel has finished
device probes.
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# Tset Sboot_verbose DVerbose boot messages
set boot_verbose
Setting this variable causes extra debugging information to be printed
by the kernel during the boot phase.
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# Tset Sconsole DSet the current console
set console[=<value>]
Sets the current console. If <value> is omitted, a list of valid
consoles will be displayed.
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# Tset Scurrdev DSet the current device
set currdev=<device>
Selects the default device. See lsdev for available devices.
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# Tset Sinit_path DSet the list of init candidates
set init_path=<path>[:<path>...]
Sets the list of binaries which the kernel will try to run as initial
process.
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# Tset Smodule_path DSet the module search path
set module_path=<path>[;<path>...]
Sets the list of directories which will be searched in for modules
named in a load command or implicitly required by a dependency. The
default module_path is "/boot/modules" with the kernel directory
prepended.
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# Tset Sprompt DSet the command prompt
set prompt=<value>
The command prompt is displayed when the loader is waiting for input.
Variable substitution is performed on the prompt. The default
prompt can be set with:
set prompt=\${interpret}
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# Tset Srootdev DSet the root filesystem
set rootdev=<path>
By default the value of $currdev is used to set the root filesystem
when the kernel is booted. This can be overridden by setting
$rootdev explicitly.
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# Tset Stunables DSet kernel tunable values
Various kernel tunable parameters can be overridden by specifying new
values in the environment.
set kern.ipc.nmbclusters=<value> NMBCLUSTERS
Set the number of mbuf clusters to be allocated. The value
cannot be set below the default determined when the kernel
was compiled.
set kern.ipc.nsfbufs=<value> NSFBUFS
Set the number of sendfile buffers to be allocated. This
overrides the value determined when the kernel was compiled.
set vm.kmem_size=<value> VM_KMEM_SIZE
Sets the size of kernel memory (bytes). This overrides
the value determined when the kernel was compiled.
set machdep.disable_mtrrs=1
Disable the use of i686 MTRRs (i386 only)
set net.inet.tcp.tcbhashsize=<value> TCBHASHSIZE
Overrides the compile-time set value of TCBHASHSIZE or
the preset default of 512. Must be a power of 2.
hw.syscons.sc_no_suspend_vtswitch=<value>
Disable VT switching on suspend.
value is 0 (default) or non-zero to enable.
set hw.physmem=<value> MAXMEM (i386 only)
Limits the amount of physical memory space available to
the system to <value> bytes. <value> may have a k, M or G
suffix to indicate kilobytes, megabytes and gigabytes
respectively. Note that the current i386 architecture
limits this value to 4GB.
On systems where memory cannot be accurately probed,
this option provides a hint as to the actual size of
system memory (which will be tested before use).
set hw.{acpi,pci}.host_start_mem=<value>
Sets the lowest address that the pci code will assign
when it doesn't have other information about the address
to assign (like from a pci bridge). This is only useful
in older systems without a pci bridge. Also, it only
impacts devices that the BIOS doesn't assign to, typically
CardBus bridges. The default <value> is 0x80000000, but
some systems need values like 0xf0000000, 0xfc000000 or
0xfe000000 may be suitable for older systems (the older
the system, the higher the number typically should be).
set hw.pci.enable_io_modes=<value>
Enable PCI resources which are left off by some BIOSes
or are not enabled correctly by the device driver.
value is 1 (default), but this may cause problems with
some peripherals. Set to 0 to disable.
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# Tshow DShow the values of variables
show [<variable>]
Displays the value of <variable>, or all variables if not specified.
Multiple paths can be separated with a semicolon.
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# Tinclude DRead commands from a script file
include <filename> [<filename> ...]
The entire contents of <filename> are read into memory before executing
commands, so it is safe to source a file from removable media.
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# Tread DRead input from the terminal
read [-t <value>] [-p <prompt>] [<variable name>]
The read command reads a line of input from the terminal. If the
-t argument is specified, it will return nothing if no input has been
received after <value> seconds. (Any keypress will cancel the
timeout).
If -p is specified, <prompt> is printed before reading input. No
newline is emitted after the prompt.
If a variable name is supplied, the variable is set to the value read,
less any terminating newline.
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# Tunload DRemove all modules from memory
unload
This command removes any kernel and all loaded modules from memory.
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# Tunset DUnset a variable
unset <variable name>
If allowed, the named variable's value is discarded and the variable
is removed.
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