freebsd-dev/sys/boot/common/help.common

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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 debugging 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_dfltroot DUse default root file system

	set boot_dfltroot

	Instructs the kernel to mount the statically compiled-in root
	file system.

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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_mute DMute the console

	set boot_mute

	All console output is suppressed when console is muted.
	In a running system, the state of console muting can be
	manipulated by the conscontrol(8) utility.

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# Tset Sboot_pause DPause after each line during device probing

	set boot_pause

	During the device probe, pause after each line is printed.

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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>

		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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