167 lines
6.5 KiB
Plaintext
Executable File
167 lines
6.5 KiB
Plaintext
Executable File
_dnl__ -*- Texinfo -*-
|
|
_dnl__ Copyright (c) 1988 1989 1990 1991 Free Software Foundation, Inc.
|
|
_dnl__ This file is part of the source for the GDB manual.
|
|
_dnl__ $Id$
|
|
@node Emacs, _GDBN__ Bugs, Sequences, Top
|
|
@chapter Using _GDBN__ under GNU Emacs
|
|
|
|
@cindex emacs
|
|
A special interface allows you to use GNU Emacs to view (and
|
|
edit) the source files for the program you are debugging with
|
|
_GDBN__.
|
|
|
|
To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the
|
|
executable file you want to debug as an argument. This command starts
|
|
_GDBN__ as a subprocess of Emacs, with input and output through a newly
|
|
created Emacs buffer.
|
|
|
|
Using _GDBN__ under Emacs is just like using _GDBN__ normally except for two
|
|
things:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
All ``terminal'' input and output goes through the Emacs buffer.
|
|
@end itemize
|
|
|
|
This applies both to _GDBN__ commands and their output, and to the input
|
|
and output done by the program you are debugging.
|
|
|
|
This is useful because it means that you can copy the text of previous
|
|
commands and input them again; you can even use parts of the output
|
|
in this way.
|
|
|
|
All the facilities of Emacs' Shell mode are available for this purpose.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
_GDBN__ displays source code through Emacs.
|
|
@end itemize
|
|
|
|
Each time _GDBN__ displays a stack frame, Emacs automatically finds the
|
|
source file for that frame and puts an arrow (_0__@samp{=>}_1__) at the
|
|
left margin of the current line. Emacs uses a separate buffer for
|
|
source display, and splits the window to show both your _GDBN__ session
|
|
and the source.
|
|
|
|
Explicit _GDBN__ @code{list} or search commands still produce output as
|
|
usual, but you probably will have no reason to use them.
|
|
|
|
@quotation
|
|
@emph{Warning:} If the directory where your program resides is not your
|
|
current directory, it can be easy to confuse Emacs about the location of
|
|
the source files, in which case the auxiliary display buffer will not
|
|
appear to show your source. _GDBN__ can find programs by searching your
|
|
environment's @code{PATH} variable, so the _GDBN__ input and output
|
|
session will proceed normally; but Emacs doesn't get enough information
|
|
back from _GDBN__ to locate the source files in this situation. To
|
|
avoid this problem, either start _GDBN__ mode from the directory where
|
|
your program resides, or specify a full path name when prompted for the
|
|
@kbd{M-x gdb} argument.
|
|
|
|
A similar confusion can result if you use the _GDBN__ @code{file} command to
|
|
switch to debugging a program in some other location, from an existing
|
|
_GDBN__ buffer in Emacs.
|
|
@end quotation
|
|
|
|
By default, @kbd{M-x gdb} calls the program called @file{gdb}. If
|
|
you need to call _GDBN__ by a different name (for example, if you keep
|
|
several configurations around, with different names) you can set the
|
|
Emacs variable @code{gdb-command-name}; for example,
|
|
@example
|
|
(setq gdb-command-name "mygdb")
|
|
@end example
|
|
@noindent
|
|
(preceded by @kbd{ESC ESC}, or typed in the @code{*scratch*} buffer, or
|
|
in your @file{.emacs} file) will make Emacs call the program named
|
|
``@code{mygdb}'' instead.
|
|
|
|
In the _GDBN__ I/O buffer, you can use these special Emacs commands in
|
|
addition to the standard Shell mode commands:
|
|
|
|
@table @kbd
|
|
@item C-h m
|
|
Describe the features of Emacs' _GDBN__ Mode.
|
|
|
|
@item M-s
|
|
Execute to another source line, like the _GDBN__ @code{step} command; also
|
|
update the display window to show the current file and location.
|
|
|
|
@item M-n
|
|
Execute to next source line in this function, skipping all function
|
|
calls, like the _GDBN__ @code{next} command. Then update the display window
|
|
to show the current file and location.
|
|
|
|
@item M-i
|
|
Execute one instruction, like the _GDBN__ @code{stepi} command; update
|
|
display window accordingly.
|
|
|
|
@item M-x gdb-nexti
|
|
Execute to next instruction, using the _GDBN__ @code{nexti} command; update
|
|
display window accordingly.
|
|
|
|
@item C-c C-f
|
|
Execute until exit from the selected stack frame, like the _GDBN__
|
|
@code{finish} command.
|
|
|
|
@item M-c
|
|
Continue execution of the program, like the _GDBN__ @code{continue}
|
|
command. @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}.
|
|
|
|
@item M-u
|
|
Go up the number of frames indicated by the numeric argument
|
|
(@pxref{Arguments, , Numeric Arguments, emacs, The GNU Emacs Manual}),
|
|
like the _GDBN__ @code{up} command. @emph{Warning:} In Emacs v19, this
|
|
command is @kbd{C-c C-u}.@refill
|
|
|
|
@item M-d
|
|
Go down the number of frames indicated by the numeric argument, like the
|
|
_GDBN__ @code{down} command. @emph{Warning:} In Emacs v19, this command
|
|
is @kbd{C-c C-d}.
|
|
|
|
@item C-x &
|
|
Read the number where the cursor is positioned, and insert it at the end
|
|
of the _GDBN__ I/O buffer. For example, if you wish to disassemble code
|
|
around an address that was displayed earlier, type @kbd{disassemble};
|
|
then move the cursor to the address display, and pick up the
|
|
argument for @code{disassemble} by typing @kbd{C-x &}.
|
|
|
|
You can customize this further on the fly by defining elements of the list
|
|
@code{gdb-print-command}; once it is defined, you can format or
|
|
otherwise process numbers picked up by @kbd{C-x &} before they are
|
|
inserted. A numeric argument to @kbd{C-x &} will both flag that you
|
|
wish special formatting, and act as an index to pick an element of the
|
|
list. If the list element is a string, the number to be inserted is
|
|
formatted using the Emacs function @code{format}; otherwise the number
|
|
is passed as an argument to the corresponding list element.
|
|
|
|
@end table
|
|
|
|
In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break})
|
|
tells _GDBN__ to set a breakpoint on the source line point is on.
|
|
|
|
If you accidentally delete the source-display buffer, an easy way to get
|
|
it back is to type the command @code{f} in the _GDBN__ buffer, to
|
|
request a frame display; when you run under Emacs, this will recreate
|
|
the source buffer if necessary to show you the context of the current
|
|
frame.
|
|
|
|
The source files displayed in Emacs are in ordinary Emacs buffers
|
|
which are visiting the source files in the usual way. You can edit
|
|
the files with these buffers if you wish; but keep in mind that _GDBN__
|
|
communicates with Emacs in terms of line numbers. If you add or
|
|
delete lines from the text, the line numbers that _GDBN__ knows will cease
|
|
to correspond properly to the code.
|
|
|
|
@c The following dropped because Epoch is nonstandard. Reactivate
|
|
@c if/when v19 does something similar. ---pesch@cygnus.com 19dec1990
|
|
@ignore
|
|
@kindex emacs epoch environment
|
|
@kindex epoch
|
|
@kindex inspect
|
|
|
|
Version 18 of Emacs has a built-in window system called the @code{epoch}
|
|
environment. Users of this environment can use a new command,
|
|
@code{inspect} which performs identically to @code{print} except that
|
|
each value is printed in its own window.
|
|
@end ignore
|