This is ../info/emacs, produced by makeinfo version 4.0 from emacs.texi.
This is the thirteenth edition of the `GNU Emacs Manual', updated
for Emacs version 20.7.
INFO-DIR-SECTION Editors
START-INFO-DIR-ENTRY
* Emacs: (emacs). The extensible self-documenting text editor.
END-INFO-DIR-ENTRY
Published by the Free Software Foundation 59 Temple Place, Suite 330
Boston, MA 02111-1307 USA
Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1996, 1997, 1998,
1999 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the sections entitled "The GNU Manifesto", "Distribution" and "GNU
General Public License" are included exactly as in the original, and
provided that the entire resulting derived work is distributed under the
terms of a permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the sections entitled "The GNU Manifesto",
"Distribution" and "GNU General Public License" may be included in a
translation approved by the Free Software Foundation instead of in the
original English.
File: emacs, Node: Checklist, Next: Sending Patches, Prev: Understanding Bug Reporting, Up: Bugs
Checklist for Bug Reports
-------------------------
The best way to send a bug report is to mail it electronically to the
Emacs maintainers at `bug-gnu-emacs@gnu.org'. (If you want to suggest
a change as an improvement, use the same address.)
If you'd like to read the bug reports, you can find them on the
newsgroup `gnu.emacs.bug'; keep in mind, however, that as a spectator
you should not criticize anything about what you see there. The
purpose of bug reports is to give information to the Emacs maintainers.
Spectators are welcome only as long as they do not interfere with
this. In particular, some bug reports contain large amounts of data;
spectators should not complain about this.
Please do not post bug reports using netnews; mail is more reliable
than netnews about reporting your correct address, which we may need in
order to ask you for more information.
If you can't send electronic mail, then mail the bug report on paper
or machine-readable media to this address:
GNU Emacs Bugs
Free Software Foundation
59 Temple Place, Suite 330
Boston, MA 02111-1307 USA
We do not promise to fix the bug; but if the bug is serious, or
ugly, or easy to fix, chances are we will want to.
A convenient way to send a bug report for Emacs is to use the command
`M-x report-emacs-bug'. This sets up a mail buffer (*note Sending
Mail::) and automatically inserts _some_ of the essential information.
However, it cannot supply all the necessary information; you should
still read and follow the guidelines below, so you can enter the other
crucial information by hand before you send the message.
To enable maintainers to investigate a bug, your report should
include all these things:
* The version number of Emacs. Without this, we won't know whether
there is any point in looking for the bug in the current version
of GNU Emacs.
You can get the version number by typing `M-x emacs-version
<RET>'. If that command does not work, you probably have something
other than GNU Emacs, so you will have to report the bug somewhere
else.
* The type of machine you are using, and the operating system name
and version number. `M-x emacs-version <RET>' provides this
information too. Copy its output from the `*Messages*' buffer, so
that you get it all and get it accurately.
* The operands given to the `configure' command when Emacs was
installed.
* A complete list of any modifications you have made to the Emacs
source. (We may not have time to investigate the bug unless it
happens in an unmodified Emacs. But if you've made modifications
and you don't tell us, you are sending us on a wild goose chase.)
Be precise about these changes. A description in English is not
enough--send a context diff for them.
Adding files of your own, or porting to another machine, is a
modification of the source.
* Details of any other deviations from the standard procedure for
installing GNU Emacs.
* The complete text of any files needed to reproduce the bug.
If you can tell us a way to cause the problem without visiting any
files, please do so. This makes it much easier to debug. If you
do need files, make sure you arrange for us to see their exact
contents. For example, it can often matter whether there are
spaces at the ends of lines, or a newline after the last line in
the buffer (nothing ought to care whether the last line is
terminated, but try telling the bugs that).
* The precise commands we need to type to reproduce the bug.
The easy way to record the input to Emacs precisely is to write a
dribble file. To start the file, execute the Lisp expression
(open-dribble-file "~/dribble")
using `M-:' or from the `*scratch*' buffer just after starting
Emacs. From then on, Emacs copies all your input to the specified
dribble file until the Emacs process is killed.
* For possible display bugs, the terminal type (the value of
environment variable `TERM'), the complete termcap entry for the
terminal from `/etc/termcap' (since that file is not identical on
all machines), and the output that Emacs actually sent to the
terminal.
The way to collect the terminal output is to execute the Lisp
expression
(open-termscript "~/termscript")
using `M-:' or from the `*scratch*' buffer just after starting
Emacs. From then on, Emacs copies all terminal output to the
specified termscript file as well, until the Emacs process is
killed. If the problem happens when Emacs starts up, put this
expression into your `.emacs' file so that the termscript file
will be open when Emacs displays the screen for the first time.
Be warned: it is often difficult, and sometimes impossible, to fix
a terminal-dependent bug without access to a terminal of the type
that stimulates the bug.
* A description of what behavior you observe that you believe is
incorrect. For example, "The Emacs process gets a fatal signal,"
or, "The resulting text is as follows, which I think is wrong."
Of course, if the bug is that Emacs gets a fatal signal, then one
can't miss it. But if the bug is incorrect text, the maintainer
might fail to notice what is wrong. Why leave it to chance?
Even if the problem you experience is a fatal signal, you should
still say so explicitly. Suppose something strange is going on,
such as, your copy of the source is out of sync, or you have
encountered a bug in the C library on your system. (This has
happened!) Your copy might crash and the copy here might not. If
you _said_ to expect a crash, then when Emacs here fails to crash,
we would know that the bug was not happening. If you don't say to
expect a crash, then we would not know whether the bug was
happening--we would not be able to draw any conclusion from our
observations.
* If the manifestation of the bug is an Emacs error message, it is
important to report the precise text of the error message, and a
backtrace showing how the Lisp program in Emacs arrived at the
error.
To get the error message text accurately, copy it from the
`*Messages*' buffer into the bug report. Copy all of it, not just
part.
To make a backtrace for the error, evaluate the Lisp expression
`(setq debug-on-error t)' before the error happens (that is to
say, you must execute that expression and then make the bug
happen). This causes the error to run the Lisp debugger, which
shows you a backtrace. Copy the text of the debugger's backtrace
into the bug report.
This use of the debugger is possible only if you know how to make
the bug happen again. If you can't make it happen again, at least
copy the whole error message.
* Check whether any programs you have loaded into the Lisp world,
including your `.emacs' file, set any variables that may affect the
functioning of Emacs. Also, see whether the problem happens in a
freshly started Emacs without loading your `.emacs' file (start
Emacs with the `-q' switch to prevent loading the init file). If
the problem does _not_ occur then, you must report the precise
contents of any programs that you must load into the Lisp world in
order to cause the problem to occur.
* If the problem does depend on an init file or other Lisp programs
that are not part of the standard Emacs system, then you should
make sure it is not a bug in those programs by complaining to
their maintainers first. After they verify that they are using
Emacs in a way that is supposed to work, they should report the
bug.
* If you wish to mention something in the GNU Emacs source, show the
line of code with a few lines of context. Don't just give a line
number.
The line numbers in the development sources don't match those in
your sources. It would take extra work for the maintainers to
determine what code is in your version at a given line number, and
we could not be certain.
* Additional information from a C debugger such as GDB might enable
someone to find a problem on a machine which he does not have
available. If you don't know how to use GDB, please read the GDB
manual--it is not very long, and using GDB is easy. You can find
the GDB distribution, including the GDB manual in online form, in
most of the same places you can find the Emacs distribution. To
run Emacs under GDB, you should switch to the `src' subdirectory
in which Emacs was compiled, then do `gdb emacs'. It is important
for the directory `src' to be current so that GDB will read the
`.gdbinit' file in this directory.
However, you need to think when you collect the additional
information if you want it to show what causes the bug.
For example, many people send just a backtrace, but that is not
very useful by itself. A simple backtrace with arguments often
conveys little about what is happening inside GNU Emacs, because
most of the arguments listed in the backtrace are pointers to Lisp
objects. The numeric values of these pointers have no
significance whatever; all that matters is the contents of the
objects they point to (and most of the contents are themselves
pointers).
To provide useful information, you need to show the values of Lisp
objects in Lisp notation. Do this for each variable which is a
Lisp object, in several stack frames near the bottom of the stack.
Look at the source to see which variables are Lisp objects,
because the debugger thinks of them as integers.
To show a variable's value in Lisp syntax, first print its value,
then use the user-defined GDB command `pr' to print the Lisp
object in Lisp syntax. (If you must use another debugger, call
the function `debug_print' with the object as an argument.) The
`pr' command is defined by the file `.gdbinit', and it works only
if you are debugging a running process (not with a core dump).
To make Lisp errors stop Emacs and return to GDB, put a breakpoint
at `Fsignal'.
For a short listing of Lisp functions running, type the GDB
command `xbacktrace'.
If you want to examine Lisp function arguments, move up the stack,
and each time you get to a frame for the function `Ffuncall', type
these GDB commands:
p *args
pr
To print the first argument that the function received, use these
commands:
p args[1]
pr
You can print the other arguments likewise. The argument `nargs'
of `Ffuncall' says how many arguments `Ffuncall' received; these
include the Lisp function itself and the arguments for that
function.
The file `.gdbinit' defines several other commands that are useful
for examining the data types and contents of Lisp objects. Their
names begin with `x'. These commands work at a lower level than
`pr', and are less convenient, but they may work even when `pr'
does not, such as when debugging a core dump or when Emacs has had
a fatal signal.
* If the symptom of the bug is that Emacs fails to respond, don't
assume Emacs is "hung"--it may instead be in an infinite loop. To
find out which, make the problem happen under GDB and stop Emacs
once it is not responding. (If Emacs is using X Windows directly,
you can stop Emacs by typing `C-z' at the GDB job.) Then try
stepping with `step'. If Emacs is hung, the `step' command won't
return. If it is looping, `step' will return.
If this shows Emacs is hung in a system call, stop it again and
examine the arguments of the call. In your bug report, state
exactly where in the source the system call is, and what the
arguments are.
If Emacs is in an infinite loop, please determine where the loop
starts and ends. The easiest way to do this is to use the GDB
command `finish'. Each time you use it, Emacs resumes execution
until it exits one stack frame. Keep typing `finish' until it
doesn't return--that means the infinite loop is in the stack frame
which you just tried to finish.
Stop Emacs again, and use `finish' repeatedly again until you get
_back to_ that frame. Then use `next' to step through that frame.
By stepping, you will see where the loop starts and ends. Also
please examine the data being used in the loop and try to
determine why the loop does not exit when it should. Include all
of this information in your bug report.
Here are some things that are not necessary in a bug report:
* A description of the envelope of the bug--this is not necessary
for a reproducible bug.
Often people who encounter a bug spend a lot of time investigating
which changes to the input file will make the bug go away and which
changes will not affect it.
This is often time-consuming and not very useful, because the way
we will find the bug is by running a single example under the
debugger with breakpoints, not by pure deduction from a series of
examples. You might as well save time by not searching for
additional examples.
Of course, if you can find a simpler example to report _instead_ of
the original one, that is a convenience. Errors in the output
will be easier to spot, running under the debugger will take less
time, etc.
However, simplification is not vital; if you can't do this or
don't have time to try, please report the bug with your original
test case.
* A system-call trace of Emacs execution.
System-call traces are very useful for certain special kinds of
debugging, but in most cases they give little useful information.
It is therefore strange that many people seem to think that _the_
way to report information about a crash is to send a system-call
trace. Perhaps this is a habit formed from experience debugging
programs that don't have source code or debugging symbols.
In most programs, a backtrace is normally far, far more
informative than a system-call trace. Even in Emacs, a simple
backtrace is generally more informative, though to give full
information you should supplement the backtrace by displaying
variable values and printing them as Lisp objects with `pr' (see
above).
* A patch for the bug.
A patch for the bug is useful if it is a good one. But don't omit
the other information that a bug report needs, such as the test
case, on the assumption that a patch is sufficient. We might see
problems with your patch and decide to fix the problem another
way, or we might not understand it at all. And if we can't
understand what bug you are trying to fix, or why your patch
should be an improvement, we mustn't install it.
*Note Sending Patches::, for guidelines on how to make it easy for
us to understand and install your patches.
* A guess about what the bug is or what it depends on.
Such guesses are usually wrong. Even experts can't guess right
about such things without first using the debugger to find the
facts.
File: emacs, Node: Sending Patches, Prev: Checklist, Up: Bugs
Sending Patches for GNU Emacs
-----------------------------
If you would like to write bug fixes or improvements for GNU Emacs,
that is very helpful. When you send your changes, please follow these
guidelines to make it easy for the maintainers to use them. If you
don't follow these guidelines, your information might still be useful,
but using it will take extra work. Maintaining GNU Emacs is a lot of
work in the best of circumstances, and we can't keep up unless you do
your best to help.
* Send an explanation with your changes of what problem they fix or
what improvement they bring about. For a bug fix, just include a
copy of the bug report, and explain why the change fixes the bug.
(Referring to a bug report is not as good as including it, because
then we will have to look it up, and we have probably already
deleted it if we've already fixed the bug.)
* Always include a proper bug report for the problem you think you
have fixed. We need to convince ourselves that the change is
right before installing it. Even if it is correct, we might have
trouble understanding it if we don't have a way to reproduce the
problem.
* Include all the comments that are appropriate to help people
reading the source in the future understand why this change was
needed.
* Don't mix together changes made for different reasons. Send them
_individually_.
If you make two changes for separate reasons, then we might not
want to install them both. We might want to install just one. If
you send them all jumbled together in a single set of diffs, we
have to do extra work to disentangle them--to figure out which
parts of the change serve which purpose. If we don't have time
for this, we might have to ignore your changes entirely.
If you send each change as soon as you have written it, with its
own explanation, then two changes never get tangled up, and we can
consider each one properly without any extra work to disentangle
them.
* Send each change as soon as that change is finished. Sometimes
people think they are helping us by accumulating many changes to
send them all together. As explained above, this is absolutely
the worst thing you could do.
Since you should send each change separately, you might as well
send it right away. That gives us the option of installing it
immediately if it is important.
* Use `diff -c' to make your diffs. Diffs without context are hard
to install reliably. More than that, they are hard to study; we
must always study a patch to decide whether we want to install it.
Unidiff format is better than contextless diffs, but not as easy
to read as `-c' format.
If you have GNU diff, use `diff -c -F'^[_a-zA-Z0-9$]+ *('' when
making diffs of C code. This shows the name of the function that
each change occurs in.
* Avoid any ambiguity as to which is the old version and which is
the new. Please make the old version the first argument to diff,
and the new version the second argument. And please give one
version or the other a name that indicates whether it is the old
version or your new changed one.
* Write the change log entries for your changes. This is both to
save us the extra work of writing them, and to help explain your
changes so we can understand them.
The purpose of the change log is to show people where to find what
was changed. So you need to be specific about what functions you
changed; in large functions, it's often helpful to indicate where
within the function the change was.
On the other hand, once you have shown people where to find the
change, you need not explain its purpose in the change log. Thus,
if you add a new function, all you need to say about it is that it
is new. If you feel that the purpose needs explaining, it
probably does--but put the explanation in comments in the code.
It will be more useful there.
Please read the `ChangeLog' files in the `src' and `lisp'
directories to see what sorts of information to put in, and to
learn the style that we use. If you would like your name to
appear in the header line, showing who made the change, send us
the header line. *Note Change Log::.
* When you write the fix, keep in mind that we can't install a
change that would break other systems. Please think about what
effect your change will have if compiled on another type of system.
Sometimes people send fixes that _might_ be an improvement in
general--but it is hard to be sure of this. It's hard to install
such changes because we have to study them very carefully. Of
course, a good explanation of the reasoning by which you concluded
the change was correct can help convince us.
The safest changes are changes to the configuration files for a
particular machine. These are safe because they can't create new
bugs on other machines.
Please help us keep up with the workload by designing the patch in
a form that is clearly safe to install.
File: emacs, Node: Contributing, Next: Service, Prev: Bugs, Up: Top
Contributing to Emacs Development
=================================
If you would like to help pretest Emacs releases to assure they work
well, or if you would like to work on improving Emacs, please contact
the maintainers at `bug-gnu-emacs@gnu.org'. A pretester should be
prepared to investigate bugs as well as report them. If you'd like to
work on improving Emacs, please ask for suggested projects or suggest
your own ideas.
If you have already written an improvement, please tell us about it.
If you have not yet started work, it is useful to contact
`bug-gnu-emacs@gnu.org' before you start; it might be possible to
suggest ways to make your extension fit in better with the rest of
Emacs.
File: emacs, Node: Service, Next: Command Arguments, Prev: Contributing, Up: Top
How To Get Help with GNU Emacs
==============================
If you need help installing, using or changing GNU Emacs, there are
two ways to find it:
* Send a message to the mailing list `help-gnu-emacs@gnu.org', or
post your request on newsgroup `gnu.emacs.help'. (This mailing
list and newsgroup interconnect, so it does not matter which one
you use.)
* Look in the service directory for someone who might help you for a
fee. The service directory is found in the file named
`etc/SERVICE' in the Emacs distribution.
File: emacs, Node: Command Arguments, Next: Antinews, Prev: Service, Up: Top
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 `-' are "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 present in other buffers. As usual, the special
argument `--' says that all subsequent arguments are file names, not
options, even if they start with `-'.
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 `-', and the long forms that start with `--'. For
example, `-d' is a short form and `--display' is the corresponding long
form.
The long forms with `--' 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 `--display
sugar-bombs:0.0' or `--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.
Most options specify how to initialize Emacs, or set parameters for
the Emacs session. We call them "initial options". A few options
specify things to do: for example, load libraries, call functions, or
exit Emacs. These are called "action options". These and file names
together are called "action arguments". Emacs processes all the action
arguments in the order they are written.
* 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 X:: Choosing colors, under X.
* 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.
* Resources X:: Advanced use of classes and resources, under X.
* Lucid Resources:: X resources for Lucid menus.
* Motif Resources:: X resources for Motif menus.
File: emacs, Node: Action Arguments, Next: Initial Options, Up: Command Arguments
Action Arguments
================
Here is a table of the action arguments and options:
`FILE'
Visit FILE using `find-file'. *Note Visiting::.
`+LINENUM FILE'
Visit FILE using `find-file', then go to line number LINENUM in it.
`-l FILE'
`--load=FILE'
Load a Lisp library named FILE with the function `load'. *Note
Lisp Libraries::. The library can be found either in the current
directory, or in the Emacs library search path as specified with
`EMACSLOADPATH' (*note General Variables::).
`-f FUNCTION'
`--funcall=FUNCTION'
Call Lisp function FUNCTION with no arguments.
`--eval EXPRESSION'
Evaluate Lisp expression EXPRESSION.
`--insert=FILE'
Insert the contents of FILE into the current buffer. This is like
what `M-x insert-file' does. *Note Misc File Ops::.
`--kill'
Exit from Emacs without asking for confirmation.
The init file can access the values of the action arguments as the
elements of a list in the variable `command-line-args'. The init file
can override the normal processing of the action arguments, or define
new ones, by reading and setting this variable.
File: emacs, Node: Initial Options, Next: Command Example, Prev: Action Arguments, Up: Command Arguments
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 X Windows appear in the following sections.
Some initial options affect the loading of init files. The normal
actions of Emacs are to first load `site-start.el' if it exists, then
your own init file `~/.emacs' if it exists, and finally `default.el' if
it exists; certain options prevent loading of some of these files or
substitute other files for them.
`-t DEVICE'
`--terminal=DEVICE'
Use DEVICE as the device for terminal input and output.
`-d DISPLAY'
`--display=DISPLAY'
Use the X Window System and use the display named DISPLAY to open
the initial Emacs frame.
`-nw'
`--no-windows'
Don't communicate directly with X, disregarding the `DISPLAY'
environment variable even if it is set.
`-batch'
`--batch'
Run Emacs in "batch mode", which means that the text being edited
is not displayed and the standard terminal interrupt characters
such as `C-z' and `C-c' continue to have their normal effect.
Emacs in batch mode outputs to `stderr' only what would normally
be printed in the echo area under program control.
Batch mode is used for running programs written in Emacs Lisp from
shell scripts, makefiles, and so on. Normally the `-l' option or
`-f' option will be used as well, to invoke a Lisp program to do
the batch processing.
`-batch' implies `-q' (do not load an init file). It also causes
Emacs to kill itself after all command options have been
processed. In addition, auto-saving is not done except in buffers
for which it has been explicitly requested.
`-q'
`--no-init-file'
Do not load your Emacs init file `~/.emacs', or `default.el'
either.
`--no-site-file'
Do not load `site-start.el'. The options `-q', `-u' and `-batch'
have no effect on the loading of this file--this is the only
option that blocks it.
`-u USER'
`--user=USER'
Load USER's Emacs init file `~USER/.emacs' instead of your own.
`--debug-init'
Enable the Emacs Lisp debugger for errors in the init file.
`--unibyte'
Set up to 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.
Setting the environment variable `EMACS_UNIBYTE' has the same
effect.
`--multibyte'
Inhibit the effect of `EMACS_UNIBYTE', so that Emacs uses
multibyte characters by default, as usual.
File: emacs, Node: Command Example, Next: Resume Arguments, Prev: Initial Options, Up: Command Arguments
Command Argument Example
========================
Here is an example of using Emacs with arguments and options. It
assumes you have a Lisp program file called `hack-c.el' which, when
loaded, performs some useful operation on the current buffer, expected
to be a C program.
emacs -batch foo.c -l hack-c -f save-buffer >& log
This says to visit `foo.c', load `hack-c.el' (which makes changes in
the visited file), save `foo.c' (note that `save-buffer' is the
function that `C-x C-s' is bound to), and then exit back to the shell
(because of `-batch'). `-batch' also guarantees there will be no
problem redirecting output to `log', because Emacs will not assume that
it has a display terminal to work with.
File: emacs, Node: Resume Arguments, Next: Environment, Prev: Command Example, Up: Command Arguments
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
`.emacs' file (*note Hooks::):
(add-hook 'suspend-hook 'resume-suspend-hook)
(add-hook 'suspend-resume-hook 'resume-process-args)
As further preparation, you must execute the shell script
`emacs.csh' (if you use csh as your shell) or `emacs.bash' (if you use
bash as your shell). These scripts define an alias named `edit', which
will resume Emacs giving it new command line arguments such as files to
visit.
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
`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; no way to define a command that could be made the
value of `EDITOR', for example. Therefore, this feature does not take
the place of the Emacs Server feature (*note 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 `/tmp/.esrv...'
still exists. If this happens, find that file and delete it.
File: emacs, Node: Environment, Next: Display X, Prev: Resume Arguments, Up: Command Arguments
Environment Variables
=====================
This appendix describes how Emacs uses environment variables. An
environment variable is a string passed from the operating system to
Emacs, and the collection of environment variables is known as the
environment. Environment variable names are case sensitive and it is
conventional to use upper case letters only.
Because environment variables come from the operating system there
is no general way to set them; it depends on the operating system and
especially the shell that you are using. For example, here's how to set
the environment variable `ORGANIZATION' to `not very much' using bash:
export ORGANIZATION="not very much"
and here's how to do it in csh or tcsh:
setenv ORGANIZATION "not very much"
When Emacs is set-up to use the X windowing system, it inherits the
use of a large number of environment variables from the X library. See
the X documentation for more information.
* Menu:
* General Variables:: Environment variables that all versions of Emacs use.
* Misc Variables:: Certain system-specific variables.
File: emacs, Node: General Variables, Next: Misc Variables, Up: Environment
General Variables
-----------------
`AUTHORCOPY'
The name of a file used to archive news articles posted with the
GNUS package.
`CDPATH'
Used by the `cd' command to search for the directory you specify,
when you specify a relative directory name.
`DOMAINNAME'
The name of the Internet domain that the machine running Emacs is
located in. Used by the GNUS package.
`EMACS_UNIBYTE'
Defining this environment variable directs Emacs to do almost
everything with single-byte buffers and strings. It is equivalent
to using the `--unibyte' command-line option on each invocation.
*Note Initial Options::.
`EMACSDATA'
Used to initialize the variable `data-directory' used to locate the
architecture-independent files that come with Emacs. Setting this
variable overrides the setting in `paths.h' when Emacs was built.
`EMACSLOADPATH'
A colon-separated list of directories from which to load Emacs Lisp
files. Setting this variable overrides the setting in `paths.h'
when Emacs was built.
`EMACSLOCKDIR'
The directory that Emacs places lock files--files used to protect
users from editing the same files simultaneously. Setting this
variable overrides the setting in `paths.h' when Emacs was built.
`EMACSPATH'
The location of Emacs-specific binaries. Setting this variable
overrides the setting in `paths.h' when Emacs was built.
`ESHELL'
Used for shell-mode to override the `SHELL' environment variable.
`HISTFILE'
The name of the file that shell commands are saved in between
logins. This variable defaults to `~/.history' if you use (t)csh
as shell, to `~/.bash_history' if you use bash, to `~/.sh_history'
if you use ksh, and to `~/.history' otherwise.
`HOME'
The location of the user's files in the directory tree; used for
expansion of file names starting with a tilde (`~'). On MS-DOS, it
defaults to the directory from which Emacs was started, with `/bin'
removed from the end if it was present.
`HOSTNAME'
The name of the machine that Emacs is running on.
`INCPATH'
A colon-separated list of directories. Used by the `complete'
package to search for files.
`INFOPATH'
A colon-separated list of directories holding info files. Setting
this variable overrides the setting in `paths.el' when Emacs was
built.
`LANG'
`LC_ALL'
`LC_CTYPE'
The user's preferred locale. A locale name which contains
`8859-N', `8859_N' or `8859N', where N is between 1 and 4,
automatically specifies the `Latin-N' language environment when
Emacs starts up. If N is 9, that specifies `Latin-5'.
`LOGNAME'
The user's login name. See also `USER'.
`MAIL'
The name of the user's system mail inbox.
`MAILRC'
Name of file containing mail aliases. This defaults to
`~/.mailrc'.
`MH'
Name of setup file for the mh system. This defaults to
`~/.mh_profile'.
`NAME'
The real-world name of the user.
`NNTPSERVER'
The name of the news server. Used by the mh and GNUS packages.
`ORGANIZATION'
The name of the organization to which you belong. Used for
setting the `Organization:' header in your posts from the GNUS
package.
`PATH'
A colon-separated list of directories in which executables reside.
(On MS-DOS, it is semicolon-separated instead.) This variable is
used to set the Emacs Lisp variable `exec-path' which you should
consider to use instead.
`PWD'
If set, this should be the default directory when Emacs was
started.
`REPLYTO'
If set, this specifies an initial value for the variable
`mail-default-reply-to'. *Note Mail Headers::.
`SAVEDIR'
The name of a directory in which news articles are saved by
default. Used by the GNUS package.
`SHELL'
The name of an interpreter used to parse and execute programs run
from inside Emacs.
`TERM'
The name of the terminal that Emacs is running on. The variable
must be set unless Emacs is run in batch mode. On MS-DOS, it
defaults to `internal', which specifies a built-in terminal
emulation that handles the machine's own display.
`TERMCAP'
The name of the termcap library file describing how to program the
terminal specified by the `TERM' variable. This defaults to
`/etc/termcap'.
`TMPDIR'
Used by the Emerge package as a prefix for temporary files.
`TZ'
This specifies the current time zone and possibly also daylight
savings information. On MS-DOS, the default is based on country
code; see the file `msdos.c' for details.
`USER'
The user's login name. See also `LOGNAME'. On MS-DOS, this
defaults to `root'.
`VERSION_CONTROL'
Used to initialize the `version-control' variable (*note Backup
Names::).
File: emacs, Node: Misc Variables, Prev: General Variables, Up: Environment
Miscellaneous Variables
-----------------------
These variables are used only on particular configurations:
`COMSPEC'
On MS-DOS, the name of the command interpreter to use. This is
used to make a default value for the `SHELL' environment variable.
`NAME'
On MS-DOS, this variable defaults to the value of the `USER'
variable.
`TEMP'
`TMP'
On MS-DOS, these specify the name of the directory for storing
temporary files in.
`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.
`EMACSCOLORS'
Used on MS-DOS systems to set screen colors early, so that the
screen won't momentarily flash the default colors when Emacs
starts up. The value of this variable should be 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.
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.
`WINDOW_GFX'
Used when initializing the Sun windows system.
File: emacs, Node: Display X, Next: Font X, Prev: Environment, Up: Command Arguments
Specifying the Display Name
===========================
The environment variable `DISPLAY' tells all X clients, including
Emacs, where to display their windows. Its value is set up 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 use login
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 `DISPLAY' environment variable is
`HOST:DISPLAY.SCREEN', where HOST is the host name of the X Window
System server machine, DISPLAY is an arbitrarily-assigned number that
distinguishes your server (X terminal) from other servers on the same
machine, and SCREEN is a rarely-used field that allows an X server to
control multiple terminal screens. The period and the SCREEN field are
optional. If included, SCREEN is usually zero.
For example, if your host is named `glasperle' and your server is
the first (or perhaps the only) server listed in the configuration, your
`DISPLAY' is `glasperle:0.0'.
You can specify the display name explicitly when you run Emacs,
either by changing the `DISPLAY' variable, or with the option `-d
DISPLAY' or `--display=DISPLAY'. Here is an example:
emacs --display=glasperle:0 &
You can inhibit the direct use of X with the `-nw' option. This is
also an initial option. It tells Emacs to display using ordinary ASCII
on its controlling terminal.
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:
Xlib: connection to "glasperle:0.0" refused by server
You might be able to overcome this problem by using the `xhost' command
on the local system to give permission for access from your remote
machine.
File: emacs, Node: Font X, Next: Colors X, Prev: Display X, Up: Command Arguments
Font Specification Options
==========================
By default, Emacs displays text in the font named `9x15', which
makes each character nine pixels wide and fifteen pixels high. You can
specify a different font on your command line through the option `-fn
NAME'.
`-fn NAME'
Use font NAME as the default font.
`--font=NAME'
`--font' is an alias for `-fn'.
Under X, each font has a long name which consists of eleven words or
numbers, separated by dashes. Some fonts also have shorter
nicknames--`9x15' is such a nickname. You can use either kind of name.
You can use wildcard patterns for the font name; then Emacs lets X
choose one of the fonts that match the pattern. Here is an example,
which happens to specify the font whose nickname is `6x13':
emacs -fn "-misc-fixed-medium-r-semicondensed--13-*-*-*-c-60-iso8859-1" &
You can also specify the font in your `.Xdefaults' file:
emacs.font: -misc-fixed-medium-r-semicondensed--13-*-*-*-c-60-iso8859-1
A long font name has the following form:
-MAKER-FAMILY-WEIGHT-SLANT-WIDTHTYPE-STYLE...
...-PIXELS-HEIGHT-HORIZ-VERT-SPACING-WIDTH-CHARSET
FAMILY
This is the name of the font family--for example, `courier'.
WEIGHT
This is normally `bold', `medium' or `light'. Other words may
appear here in some font names.
SLANT
This is `r' (roman), `i' (italic), `o' (oblique), `ri' (reverse
italic), or `ot' (other).
WIDTHTYPE
This is normally `condensed', `extended', `semicondensed' or
`normal'. Other words may appear here in some font names.
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.
PIXELS
This is the font height, in pixels.
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, HEIGHT and PIXELS are proportional; therefore, it is
common to specify just one of them and use `*' for the other.
HORIZ
This is the horizontal resolution, in pixels per inch, of the
screen for which the font is intended.
VERT
This is the vertical resolution, in dots 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 `*' for this and HORIZ.
SPACING
This is `m' (monospace), `p' (proportional) or `c' (character
cell). Emacs can use `m' and `c' fonts.
WIDTH
This is the average character width, in pixels, multiplied by ten.
CHARSET
This is the character set that the font depicts. Normally you
should use `iso8859-1'.
Use only fixed-width fonts--that is, fonts in which all characters
have the same width; Emacs cannot yet handle display properly for
variable-width fonts. Any font with `m' or `c' in the SPACING field of
the long name is a fixed-width font. Here's how to use the `xlsfonts'
program to list all the fixed-width fonts available on your system:
xlsfonts -fn '*x*' | egrep "^[0-9]+x[0-9]+"
xlsfonts -fn '*-*-*-*-*-*-*-*-*-*-*-m*'
xlsfonts -fn '*-*-*-*-*-*-*-*-*-*-*-c*'
To see what a particular font looks like, use the `xfd' command. For
example:
xfd -fn 6x13
displays the entire font `6x13'.
While running Emacs, you can set the font of the current frame
(*note Frame Parameters::) or for a specific kind of text (*note
Faces::).
File: emacs, Node: Colors X, Next: Window Size X, Prev: Font X, Up: Command Arguments
Window Color Options
====================
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, look at the `/usr/lib/X11/rgb.txt' file. If you do not
specify colors, 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.
Here is a list of the options for specifying colors:
`-fg COLOR'
`--foreground-color=COLOR'
Specify the foreground color.
`-bg COLOR'
`--background-color=COLOR'
Specify the background color.
`-bd COLOR'
`--border-color=COLOR'
Specify the color of the border of the X window.
`-cr COLOR'
`--cursor-color=COLOR'
Specify the color of the Emacs cursor which indicates where point
is.
`-ms COLOR'
`--mouse-color=COLOR'
Specify the color for the mouse cursor when the mouse is in the
Emacs window.
`-r'
`--reverse-video'
Reverse video--swap the foreground and background colors.
For example, to use a coral mouse cursor and a slate blue text
cursor, enter:
emacs -ms coral -cr 'slate blue' &
You can reverse the foreground and background colors through the
`-r' option or with the X resource `reverseVideo'.
File: emacs, Node: Window Size X, Next: Borders X, Prev: Colors X, Up: Command Arguments
Options for Window Geometry
===========================
The `-geometry' option controls the size and position of the initial
Emacs frame. Here is the format for specifying the window geometry:
`-g WIDTHxHEIGHT{+-}XOFFSET{+-}YOFFSET'
Specify window size WIDTH and HEIGHT (measured in character
columns and lines), and positions XOFFSET and YOFFSET (measured in
pixels).
`--geometry=WIDTHxHEIGHT{+-}XOFFSET{+-}YOFFSET'
This is another way of writing the same thing.
`{+-}' means either a plus sign or a minus sign. A plus sign before
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
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
XOFFSET and YOFFSET may themselves be positive or negative, but that
doesn't change their meaning, only their direction.
Emacs uses the same units as `xterm' does to interpret the geometry.
The WIDTH and HEIGHT are measured in characters, so a large font
creates a larger frame than a small font. The XOFFSET and YOFFSET are
measured in pixels.
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.
You do not have to specify all of the fields in the geometry
specification.
If you omit both XOFFSET and YOFFSET, the window manager decides
where to put the Emacs frame, possibly by letting you place it with the
mouse. For example, `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 `x' followed by an integer, Emacs
interprets it as the height. Thus, `81' specifies just the width;
`x45' specifies just the height.
If you start with `+' or `-', that introduces an offset, which means
both sizes are omitted. Thus, `-3' specifies the XOFFSET only. (If
you give just one offset, it is always XOFFSET.) `+3-3' specifies both
the XOFFSET and the YOFFSET, placing the frame near the bottom left of
the screen.
You can specify a default for any or all of the fields in
`.Xdefaults' file, and then override selected fields with a
`--geometry' option.