@c This is part of the Emacs manual.
-@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
+@c Copyright (C) 1985,86,87,93,94,95,1997,2001 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@iftex
@chapter Dealing with Common Problems
where the waiting occurs. We have done this for the system calls that
users are likely to want to quit from, but it's possible you will find
another. In one very common case---waiting for file input or output
-using NFS---Emacs itself knows how to quit, but most NFS implementations
+using NFS---Emacs itself knows how to quit, but many NFS implementations
simply do not allow user programs to stop waiting for NFS when the NFS
server is hung.
@kbd{C-x u} (@code{undo}) is not strictly speaking a way of canceling
a command, but you can think of it as canceling a command that already
-finished executing. @xref{Undo}.
+finished executing. @xref{Undo}, for more information
+about the undo facility.
@node Lossage, Bugs, Quitting, Top
@section Dealing with Emacs Trouble
This section describes various conditions in which Emacs fails to work
-normally, and how to recognize them and correct them.
+normally, and how to recognize them and correct them. For a list of
+additional problems you might encounter, see @ref{Bugs and problems, ,
+Bugs and problems, efaq, GNU Emacs FAQ}, and the file @file{etc/PROBLEMS}
+in the Emacs distribution. Type @kbd{C-h F} to read the FAQ; type
+@kbd{C-h P} to read the @file{PROBLEMS} file.
@menu
-* DEL Gets Help:: What to do if @key{DEL} doesn't delete.
-* Stuck Recursive:: `[...]' in mode line around the parentheses.
-* Screen Garbled:: Garbage on the screen.
-* Text Garbled:: Garbage in the text.
-* Unasked-for Search:: Spontaneous entry to incremental search.
-* Memory Full:: How to cope when you run out of memory.
-* After a Crash:: Recovering editing in an Emacs session that crashed.
-* Emergency Escape:: Emergency escape---
- What to do if Emacs stops responding.
-* Total Frustration:: When you are at your wits' end.
+* DEL Does Not Delete:: What to do if @key{DEL} doesn't delete.
+* Stuck Recursive:: `[...]' in mode line around the parentheses.
+* Screen Garbled:: Garbage on the screen.
+* Text Garbled:: Garbage in the text.
+* Unasked-for Search:: Spontaneous entry to incremental search.
+* Memory Full:: How to cope when you run out of memory.
+* After a Crash:: Recovering editing in an Emacs session that crashed.
+* Emergency Escape:: Emergency escape---
+ What to do if Emacs stops responding.
+* Total Frustration:: When you are at your wits' end.
@end menu
-@node DEL Gets Help
+@node DEL Does Not Delete
@subsection If @key{DEL} Fails to Delete
@cindex @key{DEL} vs @key{BACKSPACE}
@cindex @key{BACKSPACE} vs @key{DEL}
+@cindex usual erasure key
- Every keyboard has a large key, a little ways above the @key{RET}
-or @key{ENTER} key, which you normally use outside Emacs to erase
-the last character that you typed. We call this key @key{DEL}.
+ Every keyboard has a large key, a little ways above the @key{RET} or
+@key{ENTER} key, which you normally use outside Emacs to erase the
+last character that you typed. We call this key @dfn{the usual
+erasure key}. In Emacs, it is supposed to be equivalent to @key{DEL},
+and when Emacs is properly configured for your terminal, it translates
+that key into the character @key{DEL}.
When Emacs starts up using a window system, it determines
automatically which key should be @key{DEL}. In some unusual cases
-Emacs gets the wrong information from the system. If the @key{DEL}
-key deletes forwards instead of backwards, that is probably what
-happened---Emacs ought to be treating the @key{DELETE} key as
+Emacs gets the wrong information from the system. If the usual
+erasure key deletes forwards instead of backwards, that is probably
+what happened---Emacs ought to be treating the @key{DELETE} key as
@key{DEL}, but it isn't.
- With a window system, if the @key{DEL} key says @key{BACKSPACE} and
-there is a @key{DELETE} key elsewhere, but the @key{DELETE} key
-deletes backward instead of forward, that too suggests Emacs got the
-wrong information---but in the opposite sense. It ought to be
-treating the @key{BACKSPACE} key as @key{DEL}, but it isn't.
+ With a window system, if the usual erasure key is labeled
+@key{BACKSPACE} and there is a @key{DELETE} key elsewhere, but the
+@key{DELETE} key deletes backward instead of forward, that too
+suggests Emacs got the wrong information---but in the opposite sense.
+It ought to be treating the @key{BACKSPACE} key as @key{DEL}, and
+treating @key{DELETE} differently, but it isn't.
- On a text-only terminal, if you find the @key{DEL} key prompts for a
-Help command like @kbd{Control-h}, instead of deleting a character, it
-means that key is actually sending the @key{BS} character. Emacs
-ought to be treating @key{BS} as @key{DEL}, but it isn't.
+ On a text-only terminal, if you find the usual erasure key prompts
+for a Help command, like @kbd{Control-h}, instead of deleting a
+character, it means that key is actually sending the @key{BS}
+character. Emacs ought to be treating @key{BS} as @key{DEL}, but it
+isn't.
In all of those cases, the immediate remedy is the same: use the
-command @kbd{M-x normal-erase-is-backspace-mode}. That should make
-the proper @key{DEL} key work. On a text-only terminal, if you do
-want to ask for help, use @key{F1} or @kbd{C-?}.
+command @kbd{M-x normal-erase-is-backspace-mode}. This toggles
+between the two modes that Emacs supports for handling @key{DEL}, so
+if Emacs starts in the wrong mode, it should switch to the right mode.
+On a text-only terminal, if you want to ask for help when @key{BS} is
+treated as @key{DEL}, use @key{F1}; @kbd{C-?} may also work, if it
+sends character code 127.
@findex normal-erase-is-backspace-mode
To fix the problem automatically for every Emacs session, you can
put one of the following lines into your @file{.emacs} file
-(@pxref{Init File}). For the first case above, where @key{DEL}
-deletes forwards instead of backwards, use this line:
+(@pxref{Init File}). For the first case above, where @key{DELETE}
+deletes forwards instead of backwards, use this line to make
+@key{DELETE} act as @key{DEL} (resulting in behavior compatible
+with Emacs 20 and previous versions):
@lisp
(normal-erase-is-backspace-mode 0)
@end lisp
@noindent
-For the other two cases, use this line:
+For the other two cases, where @key{BACKSPACE} ought to act as
+@key{DEL}, use this line:
@lisp
(normal-erase-is-backspace-mode 1)
@key{DEL}, and @code{nil} specifies the other mode. @xref{Easy
Customization}.
+ With a window system, it can also happen that the usual erasure key
+is labeled @key{BACKSPACE}, there is a @key{DELETE} key elsewhere, and
+both keys delete forward. This probably means that someone has
+redefined your @key{BACKSPACE} key as a @key{DELETE} key. With X,
+this is typically done with a command to the @code{xmodmap} program
+when you start the server or log in. The most likely motive for this
+customization was to support old versions of Emacs, so we recommend
+you simply remove it now.
+
@node Stuck Recursive
@subsection Recursive Editing Levels
If the data on the screen looks wrong, the first thing to do is see
whether the text is really wrong. Type @kbd{C-l} to redisplay the
entire screen. If the screen appears correct after this, the problem
-was entirely in the previous screen update. (Otherwise, see @ref{Text
-Garbled}.)
+was entirely in the previous screen update. (Otherwise, see the following
+section.)
Display updating problems often result from an incorrect termcap entry
for the terminal you are using. The file @file{etc/TERMS} in the Emacs
available, in case you run out of memory another time.
Do not use @kbd{M-x buffer-menu} to save or kill buffers when you run
-out of memory, because the buffer menu needs a fair amount memory
+out of memory, because the buffer menu needs a fair amount of memory
itself, and the reserve supply may not be enough.
@node After a Crash
@kbd{n} to both questions, and you will arrive at your former state.
Presumably the quit you requested will happen soon.
- The double-@kbd{C-g} feature is turned off when Emacs is running under
+ The double @kbd{C-g} feature is turned off when Emacs is running under
the X Window System, since you can use the window manager to kill Emacs
or to create another window and run another program.
To make it possible for us to fix a bug, you must report it. In order
to do so effectively, you must know when and how to do it.
+ Before reporting a bug, it is a good idea to see if it is already
+known. You can find the list of known problems in the file
+@file{etc/PROBLEMS} in the Emacs distribution; type @kbd{C-h P} to read
+it. Some additional user-level problems can be found in @ref{Bugs and
+problems, , Bugs and problems, efaq, GNU Emacs FAQ}. Looking up your
+problem in these two documents might provide you with a solution or a
+work-around, or give you additional information about related issues.
+
@menu
* Criteria: Bug Criteria. Have you really found a bug?
* Understanding Bug Reporting:: How to report a bug effectively.
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.
+interfere with this. In particular, some bug reports contain fairly
+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.
+than netnews about reporting your correct address, which we may need
+in order to ask you for more information. If your data is more than
+500,000 bytes, please don't include it directly in the bug report;
+instead, offer to send it on request, or make it available by ftp and
+say where.
If you can't send electronic mail, then mail the bug report on paper
or machine-readable media to this address:
@item
If non-ASCII text or internationalization is relevant, the locale that
was current when you started Emacs. On GNU/Linux and Unix systems, or
-if you use a Unix-style shell such as Bash, you can use this shell
+if you use a Posix-style shell such as Bash, you can use this shell
command to view the relevant values:
-@example
-echo LC_ALL=$LC_ALL LC_CTYPE=$LC_CTYPE LANG=$LANG
-@end example
+@smallexample
+echo LC_ALL=$LC_ALL LC_COLLATE=$LC_COLLATE LC_CTYPE=$LC_CTYPE \
+ LC_MESSAGES=$LC_MESSAGES LC_TIME=$LC_TIME LANG=$LANG
+@end smallexample
Alternatively, use the @command{locale} command, if your system has it,
to display your locale settings.
You can use the @kbd{M-!} command to execute these commands from
Emacs, and then copy the output from the @samp{*Messages*} buffer into
the bug report. Alternatively, @kbd{M-x getenv @key{RET} LC_ALL
-@key{RET}} will print the value of @code{LC_ALL} in the echo area, and
+@key{RET}} will display the value of @code{LC_ALL} in the echo area, and
you can copy its output from the @samp{*Messages*} buffer.
@item
@samp{*Messages*} buffer into the bug report. Copy all of it, not just
part.
-To make a backtrace for the error, evaluate the Lisp expression
-@code{(setq @w{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.
+@findex toggle-debug-on-error
+@pindex Edebug
+To make a backtrace for the error, use @kbd{M-x toggle-debug-on-error}
+before the error happens (that is to say, you must give that command
+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. @xref{Debugger,, The Lisp
+Debugger, elisp, the Emacs Lisp Reference Manual}, for information on
+debugging Emacs Lisp programs with the Edebug package.
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
@code{Fsignal}.
For a short listing of Lisp functions running, type the GDB
-command @code{xbacktrace}.
+command @code{xbacktrace}.
The file @file{.gdbinit} defines several other commands that are useful
for examining the data types and contents of Lisp objects. Their names
whereby Emacs stops responding (many people assume that Emacs is
``hung,'' whereas in fact it might be in an infinite loop).
-In an installed Emacs, the file @file{etc/DEBUG} is in the same
-directory where the Emacs on-line documentation file @file{DOC},
-typically in the @file{/usr/local/share/emacs/@var{version}/etc/}
-directory. The directory for your installation is stored in the
-variable @code{data-directory}.
+To find the file @file{etc/DEBUG} in your Emacs installation, use the
+directory name stored in the variable @code{data-directory}.
@end itemize
Here are some things that are not necessary in a bug report:
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.
+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.
+It is better to send the bug report right away, go back to editing,
+and find another bug to report.
Of course, if you can find a simpler example to report @emph{instead} of
the original one, that is a convenience. Errors in the output will be
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.
+@item
+A core dump file.
+
+Debugging the core dump might be useful, but it can only be done on
+your machine, with your Emacs executable. Therefore, sending the core
+dump file to the Emacs maintainers won't be useful. Above all, don't
+include the core file in an email bug report! Such a large message
+can be extremely inconvenient.
+
@item
A system-call trace of Emacs execution.
HCoop / bpt / emacs.git / blobdiff