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* docs/grub.texi (Simple configuration): Document GRUB_CMDLINE_XEN

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and GRUB_CMDLINE_XEN_DEFAULT.  Recommend setting
GRUB_GFXPAYLOAD_LINUX=text rather than unsetting it in order to
disable gfxpayload.
(Shell-like scripting): Add real content.
(Serial terminal): Suggest `terminal_input serial; terminal_output
serial' rather than putting the two commands on separate lines,
since console input will be inoperative after the first command.
(menuentry): Document --class, --users, and --hotkey options.
(terminfo): Describe what `visually-ordered UTF-8' means (thanks,
Vladimir Serbinenko).
This commit is contained in:
Colin Watson 2010-08-01 11:25:09 -05:00
parent 7decd202a7
commit 2cfb45df5e
2 changed files with 186 additions and 10 deletions

14
ChangeLog
View file

@ -1,3 +1,17 @@
2010-08-01 Colin Watson <cjwatson@ubuntu.com>
* docs/grub.texi (Simple configuration): Document GRUB_CMDLINE_XEN
and GRUB_CMDLINE_XEN_DEFAULT. Recommend setting
GRUB_GFXPAYLOAD_LINUX=text rather than unsetting it in order to
disable gfxpayload.
(Shell-like scripting): Add real content.
(Serial terminal): Suggest `terminal_input serial; terminal_output
serial' rather than putting the two commands on separate lines,
since console input will be inoperative after the first command.
(menuentry): Document --class, --users, and --hotkey options.
(terminfo): Describe what `visually-ordered UTF-8' means (thanks,
Vladimir Serbinenko).
2010-08-01 Vladimir Serbinenko <phcoder@gmail.com>
2010-08-01 Colin Watson <cjwatson@ubuntu.com>

182
docs/grub.texi
View file

@ -1062,6 +1062,11 @@ only to the default menu entry, after those listed in
As @samp{GRUB_CMDLINE_LINUX} and @samp{GRUB_CMDLINE_LINUX_DEFAULT}, but for
NetBSD.
@item GRUB_CMDLINE_XEN
@itemx GRUB_CMDLINE_XEN_DEFAULT
As @samp{GRUB_CMDLINE_LINUX} and @samp{GRUB_CMDLINE_LINUX_DEFAULT}, but for
Linux and Xen.
@item GRUB_DISABLE_LINUX_UUID
Normally, @command{grub-mkconfig} will generate menu entries that use
universally-unique identifiers (UUIDs) to identify the root filesystem to
@ -1113,8 +1118,8 @@ try several modes in sequence.
Depending on your kernel, your distribution, your graphics card, and the
phase of the moon, note that using this option may cause GNU/Linux to suffer
from various display problems, particularly during the early part of the
boot sequence. If you have problems, simply unset this option and GRUB will
tell Linux to boot in normal text mode.
boot sequence. If you have problems, set this option to @samp{text} and
GRUB will tell Linux to boot in normal text mode.
@item GRUB_DISABLE_OS_PROBER
Normally, @command{grub-mkconfig} will try to use the external
@ -1143,6 +1148,142 @@ that file, making sure to leave at least the first two lines intact.
@node Shell-like scripting
@section Writing full configuration files directly
@c Some of this section is derived from the GNU Bash manual page, also
@c copyrighted by the FSF.
@file{grub.cfg} is written in GRUB's built-in scripting language, which has
a syntax quite similar to that of GNU Bash and other Bourne shell
derivatives.
@heading Words
A @dfn{word} is a sequence of characters considered as a single unit by
GRUB. Words are separated by @dfn{metacharacters}, which are the following
plus space, tab, and newline:
@example
@{ @} | & $ ; < >
@end example
Quoting may be used to include metacharacters in words; see below.
@heading Reserved words
Reserved words have a special meaning to GRUB. The following words are
recognised as reserved when unquoted and either the first word of a simple
command or the third word of a @code{for} command:
@example
! [[ ]] @{ @}
case do done elif else esac fi for function
if in menuentry select then time until while
@end example
Not all of these reserved words have a useful purpose yet; some are reserved
for future expansion.
@heading Quoting
Quoting is used to remove the special meaning of certain characters or
words. It can be used to treat metacharacters as part of a word, to prevent
reserved words from being recognised as such, and to prevent variable
expansion.
There are three quoting mechanisms: the escape character, single quotes, and
double quotes.
A non-quoted backslash (\) is the @dfn{escape character}. It preserves the
literal value of the next character that follows, with the exception of
newline.
Enclosing characters in single quotes preserves the literal value of each
character within the quotes. A single quote may not occur between single
quotes, even when preceded by a backslash.
Enclosing characters in double quotes preserves the literal value of all
characters within the quotes, with the exception of @samp{$} and @samp{\}.
The @samp{$} character retains its special meaning within double quotes.
The backslash retains its special meaning only when followed by one of the
following characters: @samp{$}, @samp{"}, @samp{\}, or newline. A
backslash-newline pair is treated as a line continuation (that is, it is
removed from the input stream and effectively ignored). A double quote may
be quoted within double quotes by preceding it with a backslash.
@heading Variable expansion
The @samp{$} character introduces variable expansion. The variable name to
be expanded may be enclosed in braces, which are optional but serve to
protect the variable to be expanded from characters immediately following it
which could be interpreted as part of the name.
Normal variable names begin with an alphabetic character, followed by zero
or more alphanumeric characters.
Positional variable names consist of one or more digits. These are reserved
for future expansion.
The special variable name @samp{?} expands to the exit status of the most
recently executed command.
@heading Comments
A word beginning with @samp{#} causes that word and all remaining characters
on that line to be ignored.
@heading Simple commands
A @dfn{simple command} is a sequence of words separated by spaces or tabs
and terminated by a semicolon or a newline. The first word specifies the
command to be executed. The remaining words are passed as arguments to the
invoked command.
The return value of a simple command is its exit status.
@heading Compound commands
A @dfn{compound command} is one of the following:
@table @asis
@item for @var{name} in @var{word} @dots{}; do @var{list}; done
The list of words following @code{in} is expanded, generating a list of
items. The variable @var{name} is set to each element of this list in turn,
and @var{list} is executed each time. The return value is the exit status
of the last command that executes. If the expansion of the items following
@code{in} results in an empty list, no commands are executed, and the return
status is 0.
@item if @var{list}; then @var{list}; [elif @var{list}; then @var{list};] @dots{} [else @var{list};] fi
The @code{if} @var{list} is executed. If its exit status is zero, the
@code{then} @var{list} is executed. Otherwise, each @code{elif} @var{list}
is executed in turn, and if its exit status is zero, the corresponding
@code{then} @var{list} is executed and the command completes. Otherwise,
the @code{else} @var{list} is executed, if present. The exit status is the
exit status of the last command executed, or zero if no condition tested
true.
@item while @var{cond}; do @var{list}; done
@itemx until @var{cond}; do @var{list}; done
The @code{while} command continuously executes the @code{do} @var{list} as
long as the last command in @var{cond} returns an exit status of zero. The
@code{until} command is identical to the @code{while} command, except that
the test is negated; the @code{do} @var{list} is executed as long as the
last command in @var{cond} returns a non-zero exit status. The exit status
of the @code{while} and @code{until} commands is the exit status of the last
@code{do} @var{list} command executed, or zero if none was executed.
@item function @var{name} @{ @var{command}; @dots{} @}
This defines a function named @var{name}. The @dfn{body} of the function is
the list of commands within braces, each of which must be terminated with a
semicolon or a newline. This list of commands will be executed whenever
@var{name} is specified as the name of a simple command. Function
definitions do not affect the exit status in @code{$?}. When executed, the
exit status of a function is the exit status of the last command executed in
the body.
@item menuentry @var{title} [@option{--class=class} @dots{}] [@option{--users=users}] [@option{--hotkey=key}] @{ @var{command}; @dots{} @}
@xref{menuentry}.
@end table
@node Embedded configuration
@section Embedding a configuration file into GRUB
@ -1308,8 +1449,7 @@ simple. Here is an example:
@example
@group
grub> @kbd{serial --unit=0 --speed=9600}
grub> @kbd{terminal_input serial}
grub> @kbd{terminal_output serial}
grub> @kbd{terminal_input serial; terminal_output serial}
@end group
@end example
@ -1320,11 +1460,14 @@ command accepts many other options, so please refer to @ref{serial},
for more details.
The commands @command{terminal_input} (@pxref{terminal_input}) and
@command{terminal_output} (@pxref{terminal_output} choose which type of
@command{terminal_output} (@pxref{terminal_output}) choose which type of
terminal you want to use. In the case above, the terminal will be a
serial terminal, but you can also pass @code{console} to the command,
as @samp{terminal serial console}. In this case, a terminal in which
you press any key will be selected as a GRUB terminal.
you press any key will be selected as a GRUB terminal. In the example above,
note that you need to put both commands on the same command line, as you
will lose the ability to type commands on the console after the first
command.
However, note that GRUB assumes that your terminal emulator is
compatible with VT100 by default. This is true for most terminal
@ -1789,9 +1932,26 @@ These commands can only be used in the menu:
@node menuentry
@subsection menuentry
@deffn Command title name @dots{}
Start a new boot entry, and set its name to the contents of the rest of
the line, starting with the first non-space character.
@deffn Command menuentry @var{title} @
[@option{--class=class} @dots{}] [@option{--users=users}] @
[@option{--hotkey=key}] @
@{ @var{command}; @dots{} @}
This defines a GRUB menu entry named @var{title}. When this entry is
selected from the menu, GRUB will set the @var{chosen} environment variable
to @var{title}, execute the list of commands given within braces, and if the
last command in the list returned successfully and a kernel was loaded it
will execute the @command{boot} command.
The @option{--class} option may be used any number of times to group menu
entries into classes. Menu themes may display different classes using
different styles.
The @option{--users} option grants specific users access to specific menu
entries. @xref{Security}.
The @option{--hotkey} option associates a hotkey with a menu entry.
@var{key} may be a single letter, or one of the aliases @samp{backspace},
@samp{tab}, or @samp{delete}.
@end deffn
@ -1885,7 +2045,9 @@ The @option{-a} (@option{--ascii}), @option{-u} (@option{--utf8}), and
@option{-v} (@option{--visual-utf8}) options control how non-ASCII text is
displayed. @option{-a} specifies an ASCII-only terminal; @option{-u}
specifies logically-ordered UTF-8; and @option{-v} specifies
visually-ordered UTF-8.
"visually-ordered UTF-8" (in other words, arranged such that a terminal
emulator without bidirectional text support will display right-to-left text
in the proper order; this is not really proper UTF-8, but a workaround).
If no option or terminal type is specified, the current terminal type is
printed.