Extensible firmware interface (EFI) brings new flexibility and opportunities to users by allowing them to work in the layer between their OS and BIOS, without altering either one.
EFI SHELL COMMANDS
Shell Boot Commands
==================================================
autoboot -- View or set autoboot timeout variable
bcfg -- Displays/modifies the driver/boot configuration
boottest -- Set/View BootTest bits
clearlogs -- Clears FPL and SEL logs
dblk -- Displays the contents of blocks from a block device
lanboot -- Performs boot over lan from EFI Shell
mount -- Mounts a file system on a block device
reset -- Resets the system
tftp -- Tftp to a bootp/dhcp enabled unix boot server
vol -- Displays volume information of the file system
Shell Configuration Commands
==================================================
cpuconfig -- Deconfigure or reconfigure cpus
date -- Displays the current date or sets the systemdate
err -- Displays or changes the error level
esiproc -- Make an ESI call
errdump -- View/Clear logs
info -- Display hardware information
monarch -- View or set the monarch processor
palproc -- Make a PAL call
salproc -- Make a SAL call
time -- Displays the current time or sets the system time
ver -- Displays the version information
Shell Device Commands
=================================================
baud -- Set serial port com settings
connect -- Binds an EFI driver to a device and starts the driver
devices -- Displays the devices being managed by EFI drivers
devtree -- Displays the tree of devices of the EFI Driver Model
disconnect -- Disconnects one or more drivers from a device
dh -- Displays the handles in the EFI environment
drivers -- Displays the list of drivers of the EFI Driver Model
drvcfg -- Invokes the Driver Configuration Protocol
drvdiag -- Invokes the Driver Diagnostics Protocol
guid -- Displays all the GUIDs in the EFI environment
lanaddress -- Display LAN MAC addresses
load -- Loads and optionally connected EFI drivers
loadpcirom -- Loads a PCI Option ROM
map -- Displays or defines mappings
openinfo -- Displays the protocols on a handle and the agents
optload -- Lists all optional ROM-based efi drivers and apps
pci -- Displays PCI devices or PCI function config space
reconnect -- Reconnects one or more drivers from a device
unload -- Unloads a protocol image
Shell Memory Commands
=================================================
default -- Sets, Resets, or Clears default NVM values
dmpstore -- Displays all NVRAM variables
dmem -- Displays the contents of memory
memmap -- Displays the memory map
mm -- Displays or modifies MEM/IO/PCI
pdt -- View or set page deallocation table
Generic Shell Commands
===================================================
alias -- Displays, creates, or deletes aliases in the EFI shell
attrib -- Displays or changes the attributes of files or directories
cd -- Displays or changes the current directory
cls -- Clears the standard output with an optional background color
comp -- Compares the contents of two files
cp -- Copies one or more files/directories to another location
edit -- Edits an ASCII or UNICODE file in full screen
eficompress -- Compress a file
efidecompress -- Compress a file
exit -- Exits the EFI Shell
help -- Displays help menus, command list, or verbose help of a command
hexedit -- Edits with hex mode in full screen
ls -- Displays a list of files and subdirectories in a directory
mkdir -- Creates one or more directories
mode -- Displays or changes the mode of the console output device
mv -- Moves one or more files/directories to destination
rm -- Deletes one or more files or directories
set -- Displays, creates, changes or deletes
EFI environment variables
==================================================
setsize -- Sets the size of the file
touch -- Updates time with current time
type -- Displays the contents of a file
xchar -- Turn on/off extended character features
Shell Script Commands
====================================================
echo -- Displays messages or turns command echoing on or off for/endfor -- Executes commands for each item in a set of items
goto -- Makes batch file execution jump to another location if/endif -- Executes commands in specified conditions
pause -- Prints a message and suspends for keyboard input
stall -- Stalls the processor for some microseconds
If you get a ¨Damaged Superblock¨ error message at filesystem (fsck) check in Linux Server, Usually fsck will not be able to repair the file system due to bad super block. In these situations, we can recover the damaged super block from the backup.
Solution:
There are backups of the Superblock located on several positions and we can restore them with a simple command in a Linux server
By default in Linux, the file system creates the backup of super block in the following locations:
8193, 32768, 98304, 163840, 229376 and 294912.
Note: 8193 is only on older systems in many cases. 32768 is the most current position for the first backup
When you get this "damaged superblock or bad superblock error" and if you get a root-prompt in a recovery console, then issue the following command:
# e2fsck -b 32768 /dev/hda5
Now the System will check the filesystem with the information stored in that backup superblock and if the check was successful it will restore the backup to position 0.
If this is not successful, then try using the other copy of Superblock backup (Refer the backup location of superblock above)
Solution:
There are backups of the Superblock located on several positions and we can restore them with a simple command in a Linux server
By default in Linux, the file system creates the backup of super block in the following locations:
8193, 32768, 98304, 163840, 229376 and 294912.
Note: 8193 is only on older systems in many cases. 32768 is the most current position for the first backup
When you get this "damaged superblock or bad superblock error" and if you get a root-prompt in a recovery console, then issue the following command:
# e2fsck -b 32768 /dev/hda5
Now the System will check the filesystem with the information stored in that backup superblock and if the check was successful it will restore the backup to position 0.
If this is not successful, then try using the other copy of Superblock backup (Refer the backup location of superblock above)
No comments:
Post a Comment