(format-write-file): Add optional argument CONFIRM and make it behave

[emacs.git] / man / cmdargs.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985,86,87,93,94,95,97,2001,03,2004 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Command Arguments, X Resources, Service, Top
@appendix Command Line Arguments
@cindex command line arguments
@cindex arguments (command line)
@cindex options (command line)
@cindex switches (command line)
@cindex startup (command line arguments)

  GNU Emacs supports command line arguments to request various actions
when invoking Emacs.  These are for compatibility with other editors and
for sophisticated activities.  We don't recommend using them for
ordinary editing.

  Arguments starting with @samp{-} are @dfn{options}.  Other arguments
specify files to visit.  Emacs visits the specified files while it
starts up.  The last file name on your command line becomes the
current buffer; the other files are also visited in other buffers.  If
there are two files, they are both displayed; otherwise the last file
is displayed along with a buffer list that shows what other buffers
there are.  As with most programs, the special argument @samp{--} says
that all subsequent arguments are file names, not options, even if
they start with @samp{-}.

  Emacs command options can specify many things, such as the size and
position of the X window Emacs uses, its colors, and so on.  A few
options support advanced usage, such as running Lisp functions on files
in batch mode.  The sections of this chapter describe the available
options, arranged according to their purpose.

  There are two ways of writing options: the short forms that start with
a single @samp{-}, and the long forms that start with @samp{--}.  For
example, @samp{-d} is a short form and @samp{--display} is the
corresponding long form.

  The long forms with @samp{--} are easier to remember, but longer to
type.  However, you don't have to spell out the whole option name; any
unambiguous abbreviation is enough.  When a long option takes an
argument, you can use either a space or an equal sign to separate the
option name and the argument.  Thus, you can write either
@samp{--display sugar-bombs:0.0} or @samp{--display=sugar-bombs:0.0}.
We recommend an equal sign because it makes the relationship clearer,
and the tables below always show an equal sign.

@cindex initial options (command line)
@cindex action options (command line)
@vindex command-line-args
  Most options specify how to initialize Emacs, or set parameters for
the Emacs session.  We call them @dfn{initial options}.  A few options
specify things to do: for example, load libraries, call functions, or
terminate Emacs.  These are called @dfn{action options}.  These and file
names together are called @dfn{action arguments}.  Emacs processes all
the action arguments in the order they are written.  The @file{.emacs} file
can access the values of the action arguments as the elements of a list in
the variable @code{command-line-args}.



@menu
* Action Arguments::    Arguments to visit files, load libraries,
                          and call functions.
* Initial Options::     Arguments that take effect while starting Emacs.
* Command Example::     Examples of using command line arguments.
* Resume Arguments::    Specifying arguments when you resume a running Emacs.
* Environment::         Environment variables that Emacs uses.
* Display X::           Changing the default display and using remote login.
* Font X::              Choosing a font for text, under X.
* Colors::              Choosing display colors.
* Window Size X::       Start-up window size, under X.
* Borders X::           Internal and external borders, under X.
* Title X::             Specifying the initial frame's title.
* Icons X::             Choosing what sort of icon to use, under X.
* Misc X::              Other display options.
@end menu

@node Action Arguments
@appendixsec Action Arguments

  Here is a table of the action arguments and options:

@table @samp
@item @var{file}
@opindex --file
@itemx --file=@var{file}
@opindex --find-file
@itemx --find-file=@var{file}
@opindex --visit
@itemx --visit=@var{file}
@cindex visiting files, command-line argument
@vindex inhibit-startup-buffer-menu
Visit @var{file} using @code{find-file}.  @xref{Visiting}.
If you visit several files at startup in this way, Emacs
also displays a Buffer Menu buffer to show you what files it
has visited.  You can inhibit that by setting @code{inhibit-startup-buffer-menu} to @code{t}.

@item +@var{linenum} @var{file}
@opindex +@var{linenum}
Visit @var{file} using @code{find-file}, then go to line number
@var{linenum} in it.

@item +@var{linenum}:@var{columnnum} @var{file}
Visit @var{file} using @code{find-file}, then go to line number
@var{linenum} and put point at column number @var{columnnum}.

@need 3000
@item -l @var{file}
@opindex -l
@itemx --load=@var{file}
@opindex --load
@cindex loading Lisp libraries, command-line argument
Load a Lisp library named @var{file} with the function @code{load}.
@xref{Lisp Libraries}.  The library can be found either in the current
directory, or in the Emacs library search path as specified
with @env{EMACSLOADPATH} (@pxref{General Variables}).

@item -L @var{dir}
@opindex -L
@itemx --directory=@var{dir}
@opindex --directory
Add directory @var{dir} to the variable @code{load-path}.

@item -f @var{function}
@opindex -f
@itemx --funcall=@var{function}
@opindex --funcall
@cindex call Lisp functions, command-line argument
Call Lisp function @var{function}.  If it is an interactive function
(a command), it reads the arguments interactively just as if you had
called the same function with a key sequence.  Otherwise, it calls the
function with no arguments.

@item --eval=@var{expression}
@opindex --eval
@itemx --execute=@var{expression}
@opindex --execute
@cindex evaluate expression, command-line argument
Evaluate Lisp expression @var{expression}.

@item --insert=@var{file}
@opindex --insert
@cindex insert file contents, command-line argument
Insert the contents of @var{file} into the current buffer.  This is like
what @kbd{M-x insert-file} does.  @xref{Misc File Ops}.

@item --kill
@opindex --kill
Exit from Emacs without asking for confirmation.

@item --help
@opindex --help
Print a usage message listing all available options, then exit
successfully.

@item --version
@opindex --version
Print Emacs version, then exit successfully.
@end table

@node Initial Options
@appendixsec Initial Options

  The initial options specify parameters for the Emacs session.  This
section describes the more general initial options; some other options
specifically related to the X Window System appear in the following
sections.

  Some initial options affect the loading of init files.  The normal
actions of Emacs are to first load @file{site-start.el} if it exists,
then your own init file @file{~/.emacs} if it exists, and finally
@file{default.el} if it exists; certain options prevent loading of some
of these files or substitute other files for them.

@table @samp
@item -t @var{device}
@opindex -t
@itemx --terminal=@var{device}
@opindex --terminal
@cindex device for Emacs terminal I/O
Use @var{device} as the device for terminal input and output.
@samp{--terminal} implies @samp{--no-window-system}.

@item -d @var{display}
@opindex -d
@itemx --display=@var{display}
@opindex --display
@cindex display for Emacs frame
Use the X Window System and use the display named @var{display} to open
the initial Emacs frame.  @xref{Display X}, for more details.

@item -nw
@opindex -nw
@itemx --no-window-system
@opindex --no-window-system
@cindex disable window system
Don't communicate directly with the window system, disregarding the
@env{DISPLAY} environment variable even if it is set.  This means that
Emacs uses the terminal from which it was launched for all its display
and input.

@need 3000
@cindex batch mode
@item -batch
@opindex --batch
@itemx --batch
Run Emacs in @dfn{batch mode}, which means that the text being edited is
not displayed and the standard terminal interrupt characters such as
@kbd{C-z} and @kbd{C-c} continue to have their normal effect.  Emacs in
batch mode outputs to @code{stderr} only what would normally be displayed
in the echo area under program control, and functions which would
normally read from the minibuffer take their input from @code{stdin}.

Batch mode is used for running programs written in Emacs Lisp from
shell scripts, makefiles, and so on.  Normally the @samp{-l} option
or @samp{-f} option will be used as well, to invoke a Lisp program
to do the batch processing.

@samp{--batch} implies @samp{-q} (do not load an init file).  It also
causes Emacs to exit after processing all the command options.  In
addition, it disables auto-saving except in buffers for which it has
been explicitly requested.

@item --script @var{file}
@opindex --script
@cindex script mode
Run Emacs in batch mode, like @samp{--batch}, and then read and
execute the Lisp code in @var{file}.

The normal use of this option is in executable script files that run
Emacs.  They can start with this text on the first line

@example
#!/usr/bin/emacs --script
@end example

@noindent
which will invoke Emacs with @samp{--script} and supply the name of
the script file as @var{file}.  Emacs Lisp then treats @samp{#!}  as a
comment delimiter.

@item -q
@opindex -q
@itemx --no-init-file
@opindex --no-init-file
@cindex bypassing init and @file{default.el} file
@cindex init file, not loading
@cindex @file{default.el} file, not loading
Do not load your Emacs init file @file{~/.emacs}, or @file{default.el}
either.  Regardless of this switch, @file{site-start.el} is still loaded.
When invoked like this, Emacs does not allow saving options
changed with the @kbd{M-x customize} command and its variants.
@xref{Easy Customization}.

@item --no-site-file
@opindex --no-site-file
@cindex @file{site-start.el} file, not loading
Do not load @file{site-start.el}.  The options @samp{-q}, @samp{-u}
and @samp{--batch} have no effect on the loading of this file---this is
the only option that blocks it.

@item --no-splash
@opindex --no-splash
@vindex inhibit-startup-message
Do not display a splash screen on startup; this is equivalent to
setting the variable @code{inhibit-startup-message} to non-@code{nil}.

@item --no-desktop
@opindex --no-desktop
Do not reload any saved desktop.  @xref{Saving Emacs Sessions}.

@item -u @var{user}
@opindex -u
@itemx --user=@var{user}
@opindex --user
@cindex load init file of another user
Load @var{user}'s Emacs init file @file{~@var{user}/.emacs} instead of
your own.

@item --debug-init
@opindex --debug-init
@cindex errors in init file
Enable the Emacs Lisp debugger for errors in the init file.

@item --unibyte
@opindex --unibyte
@itemx --no-multibyte
@opindex --no-multibyte
@cindex unibyte operation, command-line argument
Do almost everything with single-byte buffers and strings.
All buffers and strings are unibyte unless you (or a Lisp program)
explicitly ask for a multibyte buffer or string.  (Note that Emacs
always loads Lisp files in multibyte mode, even if @samp{--unibyte} is
specified; see @ref{Enabling Multibyte}.)  Setting the environment
variable @env{EMACS_UNIBYTE} has the same effect.

@item --multibyte
@opindex --multibyte
@itemx --no-unibyte
@opindex --no-unibyte
Inhibit the effect of @env{EMACS_UNIBYTE}, so that Emacs
uses multibyte characters by default, as usual.
@end table

@node Command Example
@appendixsec Command Argument Example

  Here is an example of using Emacs with arguments and options.  It
assumes you have a Lisp program file called @file{hack-c.el} which, when
loaded, performs some useful operation on the current buffer, expected
to be a C program.

@example
emacs -batch foo.c -l hack-c -f save-buffer >& log
@end example

@noindent
This says to visit @file{foo.c}, load @file{hack-c.el} (which makes
changes in the visited file), save @file{foo.c} (note that
@code{save-buffer} is the function that @kbd{C-x C-s} is bound to), and
then exit back to the shell (because of @samp{--batch}).  @samp{--batch}
also guarantees there will be no problem redirecting output to
@file{log}, because Emacs will not assume that it has a display terminal
to work with.

@node Resume Arguments
@appendixsec Resuming Emacs with Arguments

  You can specify action arguments for Emacs when you resume it after
a suspension.  To prepare for this, put the following code in your
@file{.emacs} file (@pxref{Hooks}):

@c `resume-suspend-hook' is correct.  It is the name of a function.
@example
(add-hook 'suspend-hook 'resume-suspend-hook)
(add-hook 'suspend-resume-hook 'resume-process-args)
@end example

  As further preparation, you must execute the shell script
@file{emacs.csh} (if you use csh as your shell) or @file{emacs.bash}
(if you use bash as your shell).  These scripts define an alias named
@code{edit}, which will resume Emacs giving it new command line
arguments such as files to visit.  The scripts are found in the
@file{etc} subdirectory of the Emacs distribution.

  Only action arguments work properly when you resume Emacs.  Initial
arguments are not recognized---it's too late to execute them anyway.

  Note that resuming Emacs (with or without arguments) must be done from
within the shell that is the parent of the Emacs job.  This is why
@code{edit} is an alias rather than a program or a shell script.  It is
not possible to implement a resumption command that could be run from
other subjobs of the shell; there is no way to define a command that could
be made the value of @env{EDITOR}, for example.  Therefore, this feature
does not take the place of the Emacs Server feature (@pxref{Emacs
Server}).

  The aliases use the Emacs Server feature if you appear to have a
server Emacs running.  However, they cannot determine this with complete
accuracy.  They may think that a server is still running when in
actuality you have killed that Emacs, because the file
@file{/tmp/esrv@dots{}} still exists.  If this happens, find that
file and delete it.

@node Environment
@appendixsec Environment Variables
@cindex environment variables

  The @dfn{environment} is a feature of the operating system; it
consists of a collection of variables with names and values.  Each
variable is called an @dfn{environment variable}; environment variable
names are case-sensitive, and it is conventional to use upper case
letters only.  The values are all text strings.

  What makes the environment useful is that subprocesses inherit the
environment automatically from their parent process.  This means you
can set up an environment variable in your login shell, and all the
programs you run (including Emacs) will automatically see it.
Subprocesses of Emacs (such as shells, compilers, and version-control
software) inherit the environment from Emacs, too.

@findex setenv
@findex getenv
  Inside Emacs, the command @kbd{M-x getenv} gets the value of an
environment variable.  @kbd{M-x setenv} sets a variable in the Emacs
environment.  (Environment variable substitutions with @samp{$} work
in the value just as in file names; see @ref{File Names with $}.)

  The way to set environment variables outside of Emacs depends on the
operating system, and especially the shell that you are using.  For
example, here's how to set the environment variable @env{ORGANIZATION}
to @samp{not very much} using Bash:

@example
export ORGANIZATION="not very much"
@end example

@noindent
and here's how to do it in csh or tcsh:

@example
setenv ORGANIZATION "not very much"
@end example

  When Emacs is using the X Window System, various environment
variables that control X work for Emacs as well.  See the X
documentation for more information.

@menu
* General Variables::   Environment variables that all versions of Emacs use.
* Misc Variables::      Certain system-specific variables.
* MS-Windows Registry:: An alternative to the environment on MS-Windows.
@end menu

@node General Variables
@appendixsubsec General Variables

  Here is an alphabetical list of specific environment variables that
have special meanings in Emacs, giving the name of each variable and
its meaning.  Most of these variables are also used by some other
programs.  Emacs does not require any of these environment variables
to be set, but it uses their values if they are set.

@table @env
@item CDPATH
Used by the @code{cd} command to search for the directory you specify,
when you specify a relative directory name.
@item EMACS_UNIBYTE
@cindex unibyte operation, environment variable
Defining this environment variable with a nonempty value directs Emacs
to do almost everything with single-byte buffers and strings.  It is
equivalent to using the @samp{--unibyte} command-line option on each
invocation.  @xref{Initial Options}.
@item EMACSDATA
Directory for the architecture-independent files that come with Emacs.
This is used to initialize the Lisp variable @code{data-directory}.
@item EMACSDOC
Directory for the documentation string file,
@file{DOC-@var{emacsversion}}.  This is used to initialize the Lisp
variable @code{doc-directory}.
@item EMACSLOADPATH
A colon-separated list of directories@footnote{
Here and below, whenever we say ``colon-separated list of directories'',
it pertains to Unix and GNU/Linux systems.  On MS-DOS and MS-Windows,
the directories are separated by semi-colons instead, since DOS/Windows
file names might include a colon after a drive letter.}
to search for Emacs Lisp files---used to initialize @code{load-path}.
@item EMACSPATH
A colon-separated list of directories to search for executable
files---used to initialize @code{exec-path}.
@item ESHELL
Used for shell-mode to override the @env{SHELL} environment variable.
@item HISTFILE
The name of the file that shell commands are saved in between logins.
This variable defaults to @file{~/.bash_history} if you use Bash, to
@file{~/.sh_history} if you use ksh, and to @file{~/.history}
otherwise.
@item HOME
The location of the user's files in the directory tree; used for
expansion of file names starting with a tilde (@file{~}).  On MS-DOS, it
defaults to the directory from which Emacs was started, with @samp{/bin}
removed from the end if it was present.  On Windows, the default value
of @env{HOME} is @file{C:/}, the root directory of drive @file{C:}.
@item HOSTNAME
The name of the machine that Emacs is running on.
@item INCPATH
A colon-separated list of directories.  Used by the @code{complete} package
to search for files.
@item INFOPATH
A colon-separated list of directories in which to search for Info files.
@item LC_ALL
@itemx LC_COLLATE
@itemx LC_CTYPE
@itemx LC_MESSAGES
@itemx LC_MONETARY
@itemx LC_NUMERIC
@itemx LC_TIME
@itemx LANG
The user's preferred locale.  The locale has six categories, specified
by the environment variables @env{LC_COLLATE} for sorting,
@env{LC_CTYPE} for character encoding, @env{LC_MESSAGES} for system
messages, @env{LC_MONETARY} for monetary formats, @env{LC_NUMERIC} for
numbers, and @env{LC_TIME} for dates and times.  If one of these
variables is not set, the category defaults to the value of the
@env{LANG} environment variable, or to the default @samp{C} locale if
@env{LANG} is not set.  But if @env{LC_ALL} is specified, it overrides
the settings of all the other locale environment variables.

On MS-Windows, if @env{LANG} is not already set in the environment
when Emacs starts, Emacs sets it based on the system-wide default
language, which you can set in the @samp{Regional Settings} Control Panel
on some versions of MS-Windows.

The value of the @env{LC_CTYPE} category is
matched against entries in @code{locale-language-names},
@code{locale-charset-language-names}, and
@code{locale-preferred-coding-systems}, to select a default language
environment and coding system.  @xref{Language Environments}.
@item LOGNAME
The user's login name.  See also @env{USER}.
@item MAIL
The name of the user's system mail inbox.
@item MH
Name of setup file for the mh system.  (The default is @file{~/.mh_profile}.)
@item NAME
The real-world name of the user.
@item NNTPSERVER
The name of the news server.  Used by the mh and Gnus packages.
@item ORGANIZATION
The name of the organization to which you belong.  Used for setting the
`Organization:' header in your posts from the Gnus package.
@item PATH
A colon-separated list of directories in which executables reside.  This
is used to initialize the Emacs Lisp variable @code{exec-path}.
@item PWD
If set, this should be the default directory when Emacs was started.
@item REPLYTO
If set, this specifies an initial value for the variable
@code{mail-default-reply-to}.  @xref{Mail Headers}.
@item SAVEDIR
The name of a directory in which news articles are saved by default.
Used by the Gnus package.
@item SHELL
The name of an interpreter used to parse and execute programs run from
inside Emacs.
@item SMTPSERVER
The name of the outgoing mail server.  Used by the SMTP library
(@pxref{Top,,Sending mail via SMTP,smtpmail}).
@cindex background mode, on @command{xterm}
@item TERM
The type of the terminal that Emacs is using.  This variable must be
set unless Emacs is run in batch mode.  On MS-DOS, it defaults to
@samp{internal}, which specifies a built-in terminal emulation that
handles the machine's own display.  If the value of @env{TERM} indicates
that Emacs runs in non-windowed mode from @command{xterm} or a similar
terminal emulator, the background mode defaults to @samp{light}, and
Emacs will choose colors that are appropriate for a light background.
@item TERMCAP
The name of the termcap library file describing how to program the
terminal specified by the @env{TERM} variable.  This defaults to
@file{/etc/termcap}.
@item TMPDIR
Used by the Emerge package as a prefix for temporary files.
@item TZ
This specifies the current time zone and possibly also daylight
saving time information.  On MS-DOS, if @env{TZ} is not set in the
environment when Emacs starts, Emacs defines a default value as
appropriate for the country code returned by DOS.  On MS-Windows, Emacs
does not use @env{TZ} at all.
@item USER
The user's login name.  See also @env{LOGNAME}.  On MS-DOS, this
defaults to @samp{root}.
@item VERSION_CONTROL
Used to initialize the @code{version-control} variable (@pxref{Backup
Names}).
@end table

@node Misc Variables
@appendixsubsec Miscellaneous Variables

These variables are used only on particular configurations:

@table @env
@item COMSPEC
On MS-DOS and MS-Windows, the name of the command interpreter to use
when invoking batch files and commands internal to the shell.  On MS-DOS
this is also used to make a default value for the @env{SHELL} environment
variable.

@item NAME
On MS-DOS, this variable defaults to the value of the @env{USER}
variable.

@item TEMP
@itemx TMP
On MS-DOS and MS-Windows, these specify the name of the directory for
storing temporary files in.

@item EMACSTEST
On MS-DOS, this specifies a file to use to log the operation of the
internal terminal emulator.  This feature is useful for submitting bug
reports.

@item EMACSCOLORS
On MS-DOS, this specifies the screen colors.  It is useful to set them
this way, since otherwise Emacs would display the default colors
momentarily when it starts up.

The value of this variable should be the two-character encoding of the
foreground (the first character) and the background (the second
character) colors of the default face.  Each character should be the
hexadecimal code for the desired color on a standard PC text-mode
display.  For example, to get blue text on a light gray background,
specify @samp{EMACSCOLORS=17}, since 1 is the code of the blue color and
7 is the code of the light gray color.

The PC display usually supports only eight background colors.  However,
Emacs switches the DOS display to a mode where all 16 colors can be used
for the background, so all four bits of the background color are
actually used.

@item WINDOW_GFX
Used when initializing the Sun windows system.

@item PRELOAD_WINSOCK
On MS-Windows, if you set this variable, Emacs will load and initialize
the network library at startup, instead of waiting until the first
time it is required.

@item emacs_dir
On MS-Windows, @env{emacs_dir} is a special environment variable, which
indicates the full path of the directory in which Emacs is installed.
If Emacs is installed in the standard directory structure, it
calculates this value automatically.  It is not much use setting this
variable yourself unless your installation is non-standard, since
unlike other environment variables, it will be overridden by Emacs at
startup.  When setting other environment variables, such as
@env{EMACSLOADPATH}, you may find it useful to use @env{emacs_dir}
rather than hard-coding an absolute path.  This allows multiple
versions of Emacs to share the same environment variable settings, and
it allows you to move the Emacs installation directory, without
changing any environment or registry settings.
@end table

@node MS-Windows Registry
@appendixsubsec The MS-Windows System Registry
@pindex addpm, MS-Windows installation program
@cindex registry, setting environment variables and resources on MS-Windows

On MS-Windows, the installation program @command{addpm.exe} adds values
for @env{emacs_dir}, @env{EMACSLOADPATH}, @env{EMACSDATA},
@env{EMACSPATH}, @env{EMACSDOC}, @env{SHELL} and @env{TERM} to the
@file{HKEY_LOCAL_MACHINE} section of the system registry, under
@file{/Software/GNU/Emacs}.  It does this because there is no standard
place to set environment variables across different versions of
Windows.  Running @command{addpm.exe} is no longer strictly
necessary in recent versions of Emacs, but if you are upgrading from
an older version, running @command{addpm.exe} ensures that you do not have
older registry entries from a previous installation, which may not be
compatible with the latest version of Emacs.

When Emacs starts, as well as checking the environment, it also checks
the System Registry for those variables and for @env{HOME}, @env{LANG}
and @env{PRELOAD_WINSOCK}.

To determine the value of those variables, Emacs goes through the
following procedure.  First, the environment is checked.  If the
variable is not found there, Emacs looks for registry keys by that
name under @file{/Software/GNU/Emacs}; first in the
@file{HKEY_CURRENT_USER} section of the registry, and if not found
there, in the @file{HKEY_LOCAL_MACHINE} section.  Finally, if Emacs
still cannot determine the values, compiled-in defaults are used.

In addition to the environment variables above, you can also add many
of the settings which on X belong in the @file{.Xdefaults} file
(@pxref{X Resources}) to the @file{/Software/GNU/Emacs} registry key.
Settings you add to the @file{HKEY_LOCAL_MACHINE} section will affect
all users of the machine.  Settings you add to the
@file{HKEY_CURRENT_USER} section will only affect you, and will
override machine wide settings.

@node Display X
@appendixsec Specifying the Display Name
@cindex display name (X Window System)
@cindex @env{DISPLAY} environment variable

  The environment variable @env{DISPLAY} tells all X clients, including
Emacs, where to display their windows.  Its value is set by default
in ordinary circumstances, when you start an X server and run jobs
locally.  Occasionally you may need to specify the display yourself; for
example, if you do a remote login and want to run a client program
remotely, displaying on your local screen.

  With Emacs, the main reason people change the default display is to
let them log into another system, run Emacs on that system, but have the
window displayed at their local terminal.  You might need to log in
to another system because the files you want to edit are there, or
because the Emacs executable file you want to run is there.

  The syntax of the @env{DISPLAY} environment variable is
@samp{@var{host}:@var{display}.@var{screen}}, where @var{host} is the
host name of the X Window System server machine, @var{display} is an
arbitrarily-assigned number that distinguishes your server (X terminal)
from other servers on the same machine, and @var{screen} is a
rarely-used field that allows an X server to control multiple terminal
screens.  The period and the @var{screen} field are optional.  If
included, @var{screen} is usually zero.

  For example, if your host is named @samp{glasperle} and your server is
the first (or perhaps the only) server listed in the configuration, your
@env{DISPLAY} is @samp{glasperle:0.0}.

  You can specify the display name explicitly when you run Emacs, either
by changing the @env{DISPLAY} variable, or with the option @samp{-d
@var{display}} or @samp{--display=@var{display}}.  Here is an example:

@smallexample
emacs --display=glasperle:0 &
@end smallexample

  You can inhibit the direct use of the window system and GUI with the
@samp{-nw} option.  It tells Emacs to display using ordinary @acronym{ASCII} on
its controlling terminal.  This is also an initial option.

  Sometimes, security arrangements prevent a program on a remote system
from displaying on your local system.  In this case, trying to run Emacs
produces messages like this:

@smallexample
Xlib:  connection to "glasperle:0.0" refused by server
@end smallexample

@noindent
You might be able to overcome this problem by using the @command{xhost}
command on the local system to give permission for access from your
remote machine.

@node Font X
@appendixsec Font Specification Options
@cindex font name (X Window System)

  By default, Emacs displays text in a twelve point Courier font (when
using X).  You can specify a different font on your command line
through the option @samp{-fn @var{name}} (or @samp{--font}, which is
an alias for @samp{-fn}).

@table @samp
@item -fn @var{name}
@opindex -fn
@itemx --font=@var{name}
@opindex --font
@cindex specify default font from the command line
Use font @var{name} as the default font.
@end table

  Under X, each font has a long name which consists of fourteen words
or numbers, separated by dashes.  Some fonts also have shorter
nicknames.  For instance, @samp{9x15} is such a nickname.  This font
makes each character nine pixels wide and fifteen pixels high.  You
can use either kind of name.  Case is insignificant in both kinds.
You can use wildcard patterns for the font name; then Emacs lets X
choose one of the fonts that match the pattern.  The wildcard
character @samp{*} matches any sequence of characters (including none)
and @samp{?} matches any single character.  However, matching is
implementation-dependent, and can be inaccurate when wildcards match
dashes in a long name.  For reliable results, supply all 14 dashes and
use wildcards only within a field.  Here is an example, which happens
to specify the font whose nickname is @samp{6x13}:

@smallexample
emacs -fn \
  "-misc-fixed-medium-r-semicondensed--13-*-*-*-c-60-iso8859-1" &
@end smallexample

@noindent
You can also specify the font in your @file{.Xdefaults} file:

@smallexample
emacs.font: -misc-fixed-medium-r-semicondensed--13-*-*-*-c-60-iso8859-1
@end smallexample

  Note that if you use a wildcard pattern on the command line, you
need to enclose it in single or double quotes, to prevent the shell
from accidentally expanding it into a list of file names.  On the
other hand, you should not quote the name in the @file{.Xdefaults}
file.

The default font used by Emacs (under X) is:

@smallexample
-adobe-courier-medium-r-*-*-*-120-*-*-*-*-iso8859-1
@end smallexample

  A long font name has the following form:

@smallexample
-@var{maker}-@var{family}-@var{weight}-@var{slant}-@var{widthtype}-@var{style}@dots{}
@dots{}-@var{pixels}-@var{height}-@var{horiz}-@var{vert}-@var{spacing}-@var{width}-@var{registry}-@var{encoding}
@end smallexample

@table @var
@item maker
This is the name of the font manufacturer.
@item family
This is the name of the font family---for example, @samp{courier}.
@item weight
This is normally @samp{bold}, @samp{medium} or @samp{light}.  Other
words may appear here in some font names.
@item slant
This is @samp{r} (roman), @samp{i} (italic), @samp{o} (oblique),
@samp{ri} (reverse italic), or @samp{ot} (other).
@item widthtype
This is normally @samp{condensed}, @samp{extended}, @samp{semicondensed}
or @samp{normal}.  Other words may appear here in some font names.
@item style
This is an optional additional style name.  Usually it is empty---most
long font names have two hyphens in a row at this point.
@item pixels
This is the font height, in pixels.
@item height
This is the font height on the screen, measured in tenths of a printer's
point---approximately 1/720 of an inch.  In other words, it is the point
size of the font, times ten.  For a given vertical resolution,
@var{height} and @var{pixels} are proportional; therefore, it is common
to specify just one of them and use @samp{*} for the other.
@item horiz
This is the horizontal resolution, in pixels per inch, of the screen for
which the font is intended.
@item vert
This is the vertical resolution, in pixels per inch, of the screen for
which the font is intended.  Normally the resolution of the fonts on
your system is the right value for your screen; therefore, you normally
specify @samp{*} for this and @var{horiz}.
@item spacing
This is @samp{m} (monospace), @samp{p} (proportional) or @samp{c}
(character cell).
@item width
This is the average character width, in pixels, multiplied by ten.
@item registry
@itemx encoding
These together make up the X font character set that the font depicts.
(X font character sets are not the same as Emacs charsets, but they
are solutions for the same problem.)  You can use the
@command{xfontsel} program to check which choices you have.  However,
normally you should use @samp{iso8859} for @var{registry} and @samp{1}
for @var{encoding}.
@end table

@cindex listing system fonts
  You will probably want to use a fixed-width default font---that is,
a font in which all characters have the same width.  Any font with
@samp{m} or @samp{c} in the @var{spacing} field of the long name is a
fixed-width font.  Here's how to use the @command{xlsfonts} program to
list all the fixed-width fonts available on your system:

@example
xlsfonts -fn '*x*' | egrep "^[0-9]+x[0-9]+"
xlsfonts -fn '*-*-*-*-*-*-*-*-*-*-*-m*'
xlsfonts -fn '*-*-*-*-*-*-*-*-*-*-*-c*'
@end example

@noindent
To see what a particular font looks like, use the @command{xfd} command.
For example:

@example
xfd -fn 6x13
@end example

@noindent
displays the entire font @samp{6x13}.

  While running Emacs, you can set the font of the current frame
(@pxref{Frame Parameters}) or for a specific kind of text
(@pxref{Faces}).

@node Colors
@appendixsec Window Color Options
@cindex color of window
@cindex text colors, from command line

@findex list-colors-display
@cindex available colors
  On a color display, you can specify which color to use for various
parts of the Emacs display.  To find out what colors are available on
your system, type @kbd{M-x list-colors-display}, or press
@kbd{C-Mouse-2} and select @samp{Display Colors} from the pop-up menu.
If you do not specify colors, on windowed displays the default for the
background is white and the default for all other colors is black.  On a
monochrome display, the foreground is black, the background is white,
and the border is gray if the display supports that.  On terminals, the
background is usually black and the foreground is white.

  Here is a list of the command-line options for specifying colors:

@table @samp
@item -fg @var{color}
@opindex -fg
@itemx --foreground-color=@var{color}
@opindex --foreground-color
@cindex foreground color, command-line argument
Specify the foreground color.  @var{color} should be a standard color
name, or a numeric specification of the color's red, green, and blue
components as in @samp{#4682B4} or @samp{RGB:46/82/B4}.
@item -bg @var{color}
@opindex -bg
@itemx --background-color=@var{color}
@opindex --background-color
@cindex background color, command-line argument
Specify the background color.
@item -bd @var{color}
@opindex -bd
@itemx --border-color=@var{color}
@opindex --border-color
@cindex border color, command-line argument
Specify the color of the border of the X window.
@item -cr @var{color}
@opindex -cr
@itemx --cursor-color=@var{color}
@opindex --cursor-color
@cindex cursor color, command-line argument
Specify the color of the Emacs cursor which indicates where point is.
@item -ms @var{color}
@opindex -ms
@itemx --mouse-color=@var{color}
@opindex --mouse-color
@cindex mouse pointer color, command-line argument
Specify the color for the mouse cursor when the mouse is in the Emacs window.
@item -r
@opindex -r
@itemx -rv
@opindex -rv
@itemx --reverse-video
@opindex --reverse-video
@cindex reverse video, command-line argument
Reverse video---swap the foreground and background colors.
@item --color=@var{mode}
@opindex --color
@cindex standard colors on a character terminal
For a character terminal only, specify the mode of color support.  The
parameter @var{mode} can be one of the following:
@table @samp
@item never
@itemx no
Don't use colors even if the terminal's capabilities specify color
support.
@item default
@itemx auto
Same as when @option{--color} is not used at all: Emacs detects at
startup whether the terminal supports colors, and if it does, turns on
colored display.
@item always
@itemx yes
@itemx ansi8
Turn on the color support unconditionally, and use color commands
specified by the ANSI escape sequences for the 8 standard colors.
@item @var{num}
Use color mode for @var{num} colors.  If @var{num} is -1, turn off
color support (equivalent to @samp{never}); if it is 0, use the
default color support for this terminal (equivalent to @samp{auto});
otherwise use an appropriate standard mode for @var{num} colors.  If
there is no mode that supports @var{num} colors, Emacs acts as if
@var{num} were 0, i.e.@: it uses the terminal's default color support
mode.
@end table
If @var{mode} is omitted, it defaults to @var{ansi8}.
@end table

  For example, to use a coral mouse cursor and a slate blue text cursor,
enter:

@example
emacs -ms coral -cr 'slate blue' &
@end example

  You can reverse the foreground and background colors through the
@samp{-rv} option or with the X resource @samp{reverseVideo}.

  The @samp{-fg}, @samp{-bg}, and @samp{-rv} options function on
text-only terminals as well as on window systems.

@node Window Size X
@appendixsec Options for Window Size and Position
@cindex geometry of Emacs window
@cindex position and size of Emacs frame
@cindex width and height of Emacs frame
@cindex specifying fullscreen for Emacs frame

  Here is a list of the command-line options for specifying size and
position of the initial Emacs frame:

@table @samp
@item -g @var{width}x@var{height}@r{[@{}+-@r{@}}@var{xoffset}@r{@{}+-@r{@}}@var{yoffset}@r{]]}
@opindex -g
@itemx --geometry=@var{width}x@var{height}@r{[@{}+-@r{@}}@var{xoffset}@r{@{}+-@r{@}}@var{yoffset}@r{]]}
@opindex --geometry
@cindex geometry, command-line argument
Specify the size @var{width} and @var{height} (measured in character
columns and lines), and positions @var{xoffset} and @var{yoffset}
(measured in pixels).  This applies to all frames.

@item -fs
@opindex -fs
@itemx --fullscreen
@opindex --fullscreen
@cindex fullscreen, command-line argument
Specify that width and height shall be the size of the screen.

@item -fh
@opindex -fh
@itemx --fullheight
@opindex --fullheight
@cindex fullheight, command-line argument
Specify that the height shall be the height of the screen.

@item -fw
@opindex -fw
@itemx --fullwidth
@opindex --fullwidth
@cindex fullwidth, command-line argument
Specify that the width shall be the width of the screen.
@end table


@noindent
In the @samp{--geometry} option, @code{@r{@{}+-@r{@}}} means either a plus
 sign or a minus sign.  A plus
sign before @var{xoffset} means it is the distance from the left side of
the screen; a minus sign means it counts from the right side.  A plus
sign before @var{yoffset} means it is the distance from the top of the
screen, and a minus sign there indicates the distance from the bottom.
The values @var{xoffset} and @var{yoffset} may themselves be positive or
negative, but that doesn't change their meaning, only their direction.

  Emacs uses the same units as @command{xterm} does to interpret the geometry.
The @var{width} and @var{height} are measured in characters, so a large font
creates a larger frame than a small font.  (If you specify a proportional
font, Emacs uses its maximum bounds width as the width unit.)  The
@var{xoffset} and @var{yoffset} are measured in pixels.

  You do not have to specify all of the fields in the geometry
specification.  If you omit both @var{xoffset} and @var{yoffset}, the
window manager decides where to put the Emacs frame, possibly by
letting you place it with the mouse.  For example, @samp{164x55}
specifies a window 164 columns wide, enough for two ordinary width
windows side by side, and 55 lines tall.

  The default width for Emacs is 80 characters and the default height is
40 lines.  You can omit either the width or the height or both.  If
you start the geometry with an integer, Emacs interprets it as the
width.  If you start with an @samp{x} followed by an integer, Emacs
interprets it as the height.  Thus, @samp{81} specifies just the width;
@samp{x45} specifies just the height.

  If you start with @samp{+} or @samp{-}, that introduces an offset,
which means both sizes are omitted.  Thus, @samp{-3} specifies the
@var{xoffset} only.  (If you give just one offset, it is always
@var{xoffset}.)  @samp{+3-3} specifies both the @var{xoffset} and the
@var{yoffset}, placing the frame near the bottom left of the screen.

  You can specify a default for any or all of the fields in
@file{.Xdefaults} file, and then override selected fields with a
@samp{--geometry} option.

  Since the mode line and the echo area occupy the last 2 lines of the
frame, the height of the initial text window is 2 less than the height
specified in your geometry.  In non-X-toolkit versions of Emacs, the
menu bar also takes one line of the specified number.  But in the X
toolkit version, the menu bar is additional and does not count against
the specified height.  The tool bar, if present, is also additional.

  Enabling or disabling the menu bar or tool bar alters the amount of
space available for ordinary text.  Therefore, if Emacs starts up with
a tool bar (which is the default), and handles the geometry
specification assuming there is a tool bar, and then your
@file{~/.emacs} file disables the tool bar, you will end up with a
frame geometry different from what you asked for.  To get the intended
size with no tool bar, use an X resource to specify ``no tool bar''
(@pxref{Table of Resources}); then Emacs will already know there's no
tool bar when it processes the specified geometry.

  When using one of @samp{--fullscreen}, @samp{--fullwidth} or
@samp{--fullheight} there may be some space around the frame
anyway.  That is because Emacs rounds the sizes so they are an
even number of character heights and widths.

 Some window managers have options that can make them ignore both
program-specified and user-specified positions (sawfish is one).
If these are set, Emacs fails to position the window correctly.

@node Borders X
@appendixsec Internal and External Borders
@cindex borders (X Window System)

  An Emacs frame has an internal border and an external border.  The
internal border is an extra strip of the background color around the
text portion of the frame.  Emacs itself draws the internal border.
The external border is added by the window manager outside the frame;
depending on the window manager you use, it may contain various boxes
you can click on to move or iconify the window.

@table @samp
@item -ib @var{width}
@opindex -ib
@itemx --internal-border=@var{width}
@opindex --internal-border
@cindex internal border width, command-line argument
Specify @var{width} as the width of the internal border (between the text
and the main border), in pixels.

@item -bw @var{width}
@opindex -bw
@itemx --border-width=@var{width}
@opindex --border-width
@cindex main border width, command-line argument
Specify @var{width} as the width of the main border, in pixels.
@end table

  When you specify the size of the frame, that does not count the
borders.  The frame's position is measured from the outside edge of the
external border.

  Use the @samp{-ib @var{n}} option to specify an internal border
@var{n} pixels wide.  The default is 1.  Use @samp{-bw @var{n}} to
specify the width of the external border (though the window manager may
not pay attention to what you specify).  The default width of the
external border is 2.

@node Title X
@appendixsec Frame Titles

  An Emacs frame may or may not have a specified title.  The frame
title, if specified, appears in window decorations and icons as the
name of the frame.  If an Emacs frame has no specified title, the
default title has the form @samp{@var{invocation-name}@@@var{machine}}
(if there is only one frame) or the selected window's buffer name (if
there is more than one frame).

  You can specify a title for the initial Emacs frame with a command
line option:

@table @samp
@item -T @var{title}
@opindex -T
@itemx --title=@var{title}
@opindex --title
@cindex frame title, command-line argument
Specify @var{title} as the title for the initial Emacs frame.
@end table

  The @samp{--name} option (@pxref{Resources}) also specifies the title
for the initial Emacs frame.

@node Icons X
@appendixsec Icons
@cindex icons (X Window System)

  Most window managers allow the user to ``iconify'' a frame, removing
it from sight, and leaving a small, distinctive ``icon'' window in its
place.  Clicking on the icon window makes the frame itself appear again.
If you have many clients running at once, you can avoid cluttering up
the screen by iconifying most of the clients.

@table @samp
@item -i
@opindex -i
@itemx --icon-type
@opindex --icon-type
@cindex Emacs icon, a gnu
Use a picture of a gnu as the Emacs icon.

@item -iconic
@opindex --iconic
@itemx --iconic
@cindex start iconified, command-line argument
Start Emacs in iconified state.
@end table

  The @samp{-i} or @samp{--icon-type} option tells Emacs to use an icon
window containing a picture of the GNU gnu.  If omitted, Emacs lets the
window manager choose what sort of icon to use---usually just a small
rectangle containing the frame's title.

  The @samp{-iconic} option tells Emacs to begin running as an icon,
rather than showing a frame right away.  In this situation, the icon
is the only indication that Emacs has started; the text frame doesn't
appear until you deiconify it.

@node Misc X
@appendixsec Other Display Options

@table @samp
@item -hb
@opindex -hb
@itemx --horizontal-scroll-bars
@opindex --horizontal-scroll-bars
@cindex horizontal scroll bars, command-line argument
Enable horizontal scroll bars.

@item -vb
@opindex -vb
@itemx --vertical-scroll-bars
@opindex --vertical-scroll-bars
@cindex vertical scroll bars, command-line argument
Enable vertical scroll bars.

@item -lsp @var{pixels}
@opindex -lsp
@itemx --line-spacing=@var{pixels}
@opindex --line-spacing
@cindex line spacing, command-line argument
Specify @var{pixels} as additional space to put between lines, in pixels.
@end table

  The @samp{--xrm} option (@pxref{Resources}) specifies additional
X resource values.

@ignore
   arch-tag: fffecd9e-7329-4a51-a3cc-dd4a9889340e
@end ignore