FreeBSD/Linux Kernel Cross Reference
sys/boot/common/help.common

     ################################################################################
     # 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.
    
    ################################################################################
    # T? DList available commands
    
            ?
    
            Lists all available commands.
    
    ################################################################################
    # 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.
    
    ################################################################################
    # 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.
    
    ################################################################################
    # Tbcachestat DGet disk block cache stats
    
            bcachestat
    
            Displays statistics about disk cache usage.  For debugging only.
    
    ################################################################################
    # 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.
    
    ################################################################################
    # 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.
    
    ################################################################################
    # 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 devices
    
            lsdev [-v]
    
            List all of the devices from which it may be possible to load modules.
            If -v is specified, print more details.
    
    ################################################################################
    # Tlsmod DList modules
    
            lsmod [-v]
    
            List loaded modules. If [-v] is specified, print more details.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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 variable
   
           set <variable name>
           set <variable name>=<value>
   
           The set command is used to set variables.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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".
   
   ################################################################################
   # 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 DMount root file system from CD-ROM
   
           set boot_cdrom
   
           Instructs the kernel to try to mount the root file system from CD-ROM.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # Tset Sboot_dfltroot DUse default root file system
   
           set boot_dfltroot
   
           Instructs the kernel to mount the statically compiled-in root
           file system.
   
   ################################################################################
   # Tset Sboot_gdb DSelect gdb-remote mode for the kernel debugger
   
           set boot_gdb
   
           Selects gdb-remote mode for the kernel debugger by default.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # Tset Sboot_pause DPause after each line during device probing
   
           set boot_pause
   
           During the device probe, pause after each line is printed.
   
   ################################################################################
   # Tset Sboot_serial DUse serial console
   
           set boot_serial
   
           Force the use of a serial console even when an internal console
           is present.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # Tset Scurrdev DSet the current device
   
           set currdev=<device>
   
           Selects the default device.  See lsdev for available devices.
   
   ################################################################################
   # 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.
   
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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}
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # 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.
   
   ################################################################################
   # Tunload DRemove all modules from memory
   
           unload
   
           This command removes any kernel and all loaded modules from memory.
   
   ################################################################################
   # 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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