################################################################################
# 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 in `help'.  Use the `?' command
	to list most available commands.

	To boot another kernel than the default in kernel/, change directory
	to the kernel directory, and execute `loadall' and `boot' commands.
	E.g. to do a verbose boot of kernel in kernel.XXX/:

		cd
		cd kernel.XXX
		loadall
		boot -v

	If needed, disable the ACPI driver with:

		lunset acpi_load
		set hint.acpi.0.disabled=1

	If needed, disable the AHCI driver with:

		lunset ahci_load
		set hint.ahci.0.disabled=1

	If needed, disable the EHCI driver with:

		lunset ehci_load
		set hint.ehci.0.disabled=1

	For more information on ACPI, AHCI and EHCI use `help' on these topics.

################################################################################
# T<variable>=<value> DAssign value to variable

	<variable>=<value>

	Assign value to variable.  The value is always assigned to local
	variable <variable>.  If <variable> is in the list of known kernel
	environment (kenv) variables or is a kernel tunable, the value is also
	assigned to the kernel environment variable of the given name.
	If the variable name contains a `.' it is considered a kernel tunable.
	Local variables are unset if <value> is empty.  Kernel environment
	variables will have empty value.

	Two kinds of variables are maintained by loader(8) (this program):
	local variables, that is for loader(8) use only, and kernel
	environment variables, that kernel will have access to when it starts.
	The assignment described above, will assign to a local variable and,
	if applicable, also snoop assignment to kernel environment variable.

	<value> can be a string or a string expressions containing literal
	text and kernel environment variables, like `$VAR' or `${VAR}'.  E.g.:

		VAR="Current device is $currdev"

	Escape sequences like `\n' (newline) and `\OOO' (character with number
	given in octal) can also be used.  This is actually a general facility
	of loader(8) which can be used for arguments of all commands.

################################################################################
# TAHCI DControl AHCI module behaviour

	$ahci_load

	The AHCI driver provides support for SATA controllers conforming to
	the Advanced Host Controller Interface specification.

	The NATA driver provides support for some AHCI controllers, the AHCI
	driver is used if both NATA and AHCI drivers provides support for a
	controller.  If AHCI driver is disabled, NATA driver will be used.

	If the ahci_load variable is set, the AHCI module will be loaded.
	The AHCI driver can be disabled with:

		lunset ahci_load
		set hint.ahci.0.disabled=1

	A link speed of 1.5Gb/s can be enforced with:

		set hint.ahci.force150=1

	To refrain from attempting to send some higher level ATA commands
	which some devices might not properly implement use:

		set hint.ahci.nofeatures=1

	See ahci.4 man page (on booted system) for full description.

################################################################################
# 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 $autoboot_delay.

################################################################################
# Tboot DBoot immediately

	boot [-<flag> ...] [<kernelname>]

	Boot the system.  If flags 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.  <flag> values include:

	-a  Same as `set boot_askname'
	-C  Same as `set boot_cdrom'
	-c  Same as `set boot_userconfig'
	-d  Same as `set boot_ddb'
	-g  Same as `set boot_gdb'
	-h  Same as `set boot_serial'
	-m  Mute the system console
	-p  Pause after each attached device during device probing phase
	-r  Use statically configured device for root file system
	-s  Same as `set boot_single'
	-V  Same as `set boot_vidcons'
	-v  Same as `set boot_verbose'

	<flag>s can also be set via kernel_options variable.
	See also boot.8 man page (on booted system) for <flag> values.

################################################################################
# Techo DEcho arguments

	echo [-n] [<message>]

	Emits <message>, with no trailing newline if -n is specified.

	Kernel environment variables are substituted by prefixing them with
	`$', like `$VAR'; another variant is `${VAR}'.  E.g.:

		echo Current device is $currdev

	will print the current device.

################################################################################
# TEHCI DControl EHCI module behaviour

	$ehci_load

	The EHCI driver provides support for the USB Enhanched Host Controller
	Interface, which is used by USB 2.0 controllers.

	The EHCI kernel module is by default loaded automatically.

	If the ehci_load variable is set, the EHCI module will be loaded.
	The EHCI driver can be disabled with:

		lunset ehci_load
		set hint.ehci.0.disabled=1

	See ehci.4 man page (on booted system) for full description.

################################################################################
# Tload DLoad a kernel or module

	load [-t <type>] <file> [<argument> ...]

	Loads the module contained in <file> into memory.  If no other modules
	are loaded, <file> 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.

	Any arguments passed after the name of the file to be loaded will be
	passed as arguments to that file.

################################################################################
# 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.

################################################################################
# Tlsdev DList all devices

	lsdev [-v]

	List all devices.  Disk slices and partitions from which it may be
	possible to load modules are marked with '*'.
	If -v is specified, print more details, like size and position of
	disk slices and partitions.

################################################################################
# Tlsmod DList modules

	lsmod [-v]

	List loaded modules.  If -v is specified, print more details.

################################################################################
# Tmore DPage files

	more <file> ...

	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.

################################################################################
# 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.

################################################################################
# Tset DSet a kernel environment variable

	set <kenv_variable>
	set <kenv_variable>=<value>

	The set command is used to set kernel environment variables.

	See also `<variable>=<value>' command for distinction on local and
	kernel environment variables.

################################################################################
# Tset Sautoboot_delay DSet the default autoboot / menu delay

	set autoboot_delay=<value>

	Sets the default delay in seconds for the `autoboot' and `menu'
	commands to wait before booting.  The default value is 10 seconds.

################################################################################
# Tset Sbootfile DSet the default boot file set

	set bootfile=<file>[;<file>...]

	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 value is "kernel".

################################################################################
# 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.

################################################################################
# Tset Sboot_cdrom DBoot from CDROM

	set boot_cdrom

	Instructs the kernel to boot from CDROM when the kernel is booted.

################################################################################
# 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 initialise when booted.

################################################################################
# Tset Sboot_gdb DSelect gdb-remote mode

	set boot_gdb

	Selects gdb-remote mode for the kernel debugger by default.

################################################################################
# Tset Sboot_single DStart system in single-user mode

	set boot_single

	Prevents the kernel from initiating a multi-user startup, single-user
	mode will be entered when the kernel has finished device probes.

################################################################################
# Tset Sboot_serial DUse serial console after boot

	set boot_serial

	Use serial console after boot.  See also `set console' command.

################################################################################
# Tset Sboot_verbose DVerbose boot messages

	set boot_verbose

	Setting this variable causes extra debugging information to be printed
	by the kernel especially during the boot phase.

################################################################################
# Tset Sboot_vidcons DUse video console after boot

	set boot_vidcons

	Use video console after boot.  See also `set console' command.

################################################################################
# Tset Skernel_options DKernel options

	set kernel_options

	Set kernel boot flags.  E.g.:

		set kernel_options="-v -a"

	See also boot command; kernel_options sets default <flags>.

################################################################################
# Tset Sconsole DSet the current console

	set console[=<value>]

	Sets the current console.  <value> include `vidconsole', `comconsole'
	and `nullconsole'.  If <value> is omitted, a list of valid consoles
	will be displayed.

################################################################################
# Tset Sdefault_kernel DSet default kernel directory

	set default_kernel=<path>

	Selects the default kernel directory for `menu' command.  Default value
	is "kernel".

################################################################################
# Tset Scurrdev DSet the current device

	set currdev=<device>

	Selects the default device.  See `lsdev' for available devices.

################################################################################
# Tset Sinit_chroot DSet directory that init(8) will chroot() to

	set init_chroot=<path>

	If set, init(8) will chroot() to <path> on startup.  By setting this
	variable DragonFly can be run from a subdirectory of the root file
	system.

################################################################################
# Tset Sinit_path DSet the list of init(8) candidates

	set init_path=<path>[:<path>...]

	Sets the list of binaries which the kernel will try to run as initial
	process.

################################################################################
# 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.  An
	empty <path> specifies the current directory.  The default value is
	";modules".

################################################################################
# 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 value
	is "OK".

################################################################################
# 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.

	See also vfs.root.mountfrom variable, under `set tunables' help item.

################################################################################
# Tset Stunables DSet kernel tunable values

	Various kernel tunable parameters can be overridden by specifying new
	values in the environment.

	set hw.ioapic_enable=<value>

		Set to 0 to disable use of I/O APIC.  Default value is 1.

	set hw.irq.X.dest=<value>

		Set irqX's destination to the given CPUID, which starts from 0.
		This variable should not be used if I/O APIC use is disabled.

	set hw.pci.allow_unsupported_io_range=<value>

		Allow the PCI Bridge to pass through an unsupported
		memory range assigned by the BIOS.

		Value is 0 (default) or non-zero to enable.

	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 hw.physmem=<value>			MAXMEM

		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.syscons.sc_no_suspend_vtswitch=<value>

		Disable VT switching on suspend.

		Value is 0 (default) or non-zero to enable.

	set hw.usb.hack_defer_exploration=<value>

		The USB keyboard will sometimes not attach properly unless
		you set this variable to 0.

	set kern.emergency_intr_enable=<value>

		Setting this to 1 enables emergency interrupt polling.  All
		interrupt handlers are executed periodically.  This mode is
		very expensive and should only be used to get a system
		accessible when interrupt routing is otherwise broken.  It
		is primarily used by kernel developers to debug new systems.

	set kern.emergency_intr_freq=<value>

		Set the polling rate for the emergency interrupt polling
		code.  The default is 10 (hz) to dissuade causual use.  If
		you are doing real work with emergency interrupt polling
		mode enabled, it is recommended that you use a frequency
		between 100hz and 300hz.

	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.user_scheduler=<value>

		Set the default userland scheduler.  <value> can be "bsd4"
		or "dfly" (default).

	set kern.vm.kmem.size=<value>

		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.

	set vfs.root.mountfrom=<value>

		Specify root file system.  <value> is a semicolon separated
		list of file systems.  File system format is file system type
		and disk store, separated by colon.

		This variable needs to be set when using boot-only partition,
		which is typically mounted on root file system as /boot.

		One file system example:

			"hammer:da8se1a"

		One file system HAMMER2 redundant copies examples:

			"hammer2:da8s1a:da9s1a"

		Several file systems, boot list, example:

			"ufs:da0s1a;hammer2:ad1s1d"

		Each file system in the list will be tried in the order
		specified until the mount succeeds.  If all fail, the
		`mountroot>' prompt is displayed for manual entry.

		You may not specify devtab labels here but you can specify
		paths available to devfs such as:

			"hammer:serno/L41JYE0G.s1d"

	set vfs.root.realroot=<value>

		Specify root file system and extra options for initrd.

		Format of <value> is below, TYPE is `local' or `crypt',
		arg's depend on TYPE:

			"TYPE:arg1:arg2:...:argN"

		Examples of <value>:

		Use UFS file system on lvm(8) volume group `vg00' logical
		volume `lv0' as real root:

			"local:ufs:/dev/vg00/lv0"

		Use UFS file system on encrypted volume `secvolume', managed by
		cryptsetup(8), on device `/dev/ad0s0a' as real root:

			"crypt:ufs:/dev/ad0s0a:secvolume"

		See mkinitrd.8 man page (on booted system) for full description.

################################################################################
# Tshow DShow values of kernel environment variable

	show [<kenv_variable>]

	Displays the value of <kenv_variable>, or all kernel environment
	variables if not specified.

	See also `<variable>=<value>' command for distinction on local and
	kernel environment variables.

################################################################################
# Tinclude DExecute script file

	include <file> ...

	The entire contents of <file> are read into memory before executing
	commands, so it is safe to source a file from removable media.

################################################################################
# Toptinclude DExecute script file; ignore exit status

	optinclude <file> ...

	The entire contents of <file> are read into memory before executing
	commands, so it is safe to source a file from removable media.
	Return success and execute all commands even if some commands fail.

################################################################################
# Tcd DChange directory

	cd [<directory>]

	Change working directory to <directory>.  Default is $base.

################################################################################
# Toptcd DChange directory; ignore exit status

	optcd [<directory>]

	Change working directory to <directory>.  Default is $base.
	Return success even if changing directory fails.

################################################################################
# Tpwd DPrint working directory

	pwd

	Show working directory.

################################################################################
# Tlocal DList local variables

	local [<local_variable> ...]

	Display the value of given local variables, or all variables if not
	specified.

	See also `<variable>=<value>' command for distinction on local and
	kernel environment variables.

################################################################################
# Tlunset DUnset local variable

	lunset <local_variable>

	Unset local variable: discard value and remove variable.

	See also `<variable>=<value>' command for distinction on local and
	kernel environment variables.

################################################################################
# Tlunsetif DUnset local variable if kenv variable true

	lunsetif <local_variable> <kenv_variable>

	Unset local variable <local_variable> if kernel environment variable
	<kenv_variable> is true, i.e. set to 1 or YES.

	See also `<variable>=<value>' command for distinction on local and
	kernel environment variables.

################################################################################
# Tloadall DLoad kernel + modules

	loadall

	Load kernel and all modules specified by MODULE_load variables.

################################################################################
# Tifexists DConditional file/dir present

	ifexists <path>

	Conditional <path> exists, i.e. file/dir present.

################################################################################
# Tifset DConditional kenv variable present

	ifset <kenv_variable>

	Conditional kernel environment variable <kenv_variable> exists.

################################################################################
# Telseifexists DConditional file/dir present

	elseifexists <path>

	Conditional <path> exists, i.e. file/dir present.

################################################################################
# Telse DConditional if/else/endif

	else

	Conditional if/else/endif.

################################################################################
# Tendif DConditional if/else/endif

	endif

	Conditional if/else/endif.

################################################################################
# Tmenuclear DClear all menus

	menuclear

	Clear all menu bullets.

################################################################################
# Tmenuitem DAdd menu bullet

	menuitem <key> <description text>

	Start new menu bullet, when running menu system bullet is choosen by
	pressing <key>.  E.g.:

		menuitem a "Boot Backup kernel kernel.alt"

################################################################################
# Tmenuadd DAdd script line for menu bullet

	menuadd <command line>

	Add script line for current menu bullet.  E.g.:

		menuadd lunsetif acpi_load hint.acpi.0.disabled

################################################################################
# Tmenu DRun menu system

	menu

	Run menu system.

################################################################################
# Tread DRead input from terminal to kenv variable

	read [-p <prompt>] [-t <value>] [<kenv_variable>]

	The read command reads a line of input from the terminal.

	If -p is specified, <prompt> is printed before reading input.  No
	newline is emitted after the prompt.

	If -t is specified, it will return nothing if no input has been
	received after <value> seconds.  Any keypress will cancel the timeout.

	If <kenv_variable> is supplied, the kernel environment variable is set
	to the value read, less any terminating newline.

################################################################################
# Tunload DRemove all modules from memory

	unload

	This command removes any kernel and all loaded modules from memory.

################################################################################
# Tunset DUnset a kernel environment variable

	unset <kenv_variable>

	If allowed, the named kernel environment variable's value is discarded
	and the variable is removed.

	See also `<variable>=<value>' command for distinction on local and
	kernel environment variables.

################################################################################