121 lines
4 KiB
Text
121 lines
4 KiB
Text
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14 GRUB's user interface
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************************
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GRUB has both a simple menu interface for choosing preset entries from a
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configuration file, and a highly flexible command-line for performing
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any desired combination of boot commands.
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GRUB looks for its configuration file as soon as it is loaded. If
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one is found, then the full menu interface is activated using whatever
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entries were found in the file. If you choose the "command-line" menu
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option, or if the configuration file was not found, then GRUB drops to
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the command-line interface.
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14.1 The flexible command-line interface
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========================================
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The command-line interface provides a prompt and after it an editable
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text area much like a command-line in Unix or DOS. Each command is
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immediately executed after it is entered(1) (*note Command-line
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interface-Footnote-1::). The commands (*note Command-line and menu
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entry commands::) are a subset of those available in the configuration
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file, used with exactly the same syntax.
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Cursor movement and editing of the text on the line can be done via a
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subset of the functions available in the Bash shell:
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<C-f>
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<PC right key>
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Move forward one character.
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<C-b>
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<PC left key>
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Move back one character.
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<C-a>
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<HOME>
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Move to the start of the line.
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<C-e>
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<END>
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Move the the end of the line.
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<C-d>
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<DEL>
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Delete the character underneath the cursor.
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<C-h>
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<BS>
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Delete the character to the left of the cursor.
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<C-k>
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Kill the text from the current cursor position to the end of the
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line.
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<C-u>
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Kill backward from the cursor to the beginning of the line.
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<C-y>
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Yank the killed text back into the buffer at the cursor.
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<C-p>
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<PC up key>
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Move up through the history list.
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<C-n>
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<PC down key>
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Move down through the history list.
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When typing commands interactively, if the cursor is within or before
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the first word in the command-line, pressing the <TAB> key (or <C-i>)
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will display a listing of the available commands, and if the cursor is
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after the first word, the '<TAB>' will provide a completion listing of
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disks, partitions, and file names depending on the context. Note that
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to obtain a list of drives, one must open a parenthesis, as 'root ('.
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Note that you cannot use the completion functionality in the TFTP
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filesystem. This is because TFTP doesn't support file name listing for
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the security.
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(1) However, this behavior will be changed in the future version, in
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a user-invisible way.
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14.2 The simple menu interface
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==============================
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The menu interface is quite easy to use. Its commands are both
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reasonably intuitive and described on screen.
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Basically, the menu interface provides a list of "boot entries" to
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the user to choose from. Use the arrow keys to select the entry of
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choice, then press <RET> to run it. An optional timeout is available to
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boot the default entry (the first one if not set), which is aborted by
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pressing any key.
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Commands are available to enter a bare command-line by pressing <c>
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(which operates exactly like the non-config-file version of GRUB, but
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allows one to return to the menu if desired by pressing <ESC>) or to
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edit any of the "boot entries" by pressing <e>.
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If you protect the menu interface with a password (*note Security::),
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all you can do is choose an entry by pressing <RET>, or press <p> to
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enter the password.
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14.3 Editing a menu entry
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=========================
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The menu entry editor looks much like the main menu interface, but the
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lines in the menu are individual commands in the selected entry instead
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of entry names.
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If an <ESC> is pressed in the editor, it aborts all the changes made
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to the configuration entry and returns to the main menu interface.
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Each line in the menu entry can be edited freely, and you can add new
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lines by pressing <RET> at the end of a line. To boot the edited entry,
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press <Ctrl-x>.
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Although GRUB unfortunately does not support "undo", you can do
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almost the same thing by just returning to the main menu using <ESC>.
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