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.

	If needed, disable the use of ACPI with:

	unset acpi_load
	set hint.acpi.0.disabled="1"

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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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# 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.

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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.  Syntax for devices is odd.

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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=\$currdev>

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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.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.

	set vfs.root.mountdelay=<value>

		Delay root partition mount if there is no required provider.

		value is a maximum number of seconds to wait for provider to
		show up (default is 5 seconds).

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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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