* Compilation Mode:: The mode for visiting compiler errors.
* Compilation Shell:: Customizing your shell properly
for use in the compilation buffer.
-* Debuggers:: Running symbolic debuggers for non-Lisp programs.
-* Executing Lisp:: Various modes for editing Lisp programs,
+* Debuggers:: Running symbolic debuggers for non-Lisp programs.
+* Executing Lisp:: Various modes for editing Lisp programs,
with different facilities for running
- the Lisp programs.
+ the Lisp programs.
* Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs.
-* Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer.
* Eval: Lisp Eval. Executing a single Lisp expression in Emacs.
-* External Lisp:: Communicating through Emacs with a separate Lisp.
+* Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer.
+* External Lisp:: Communicating through Emacs with a separate Lisp.
@end menu
@node Compilation
directory.
@vindex compile-command
- When the shell command line is read, the minibuffer appears containing
-a default command line, which is the command you used the last time you
-did @kbd{M-x compile}. If you type just @key{RET}, the same command
-line is used again. For the first @kbd{M-x compile}, the default is
-@samp{make -k}. The default compilation command comes from the variable
+ When the shell command line is read, the minibuffer appears
+containing a default command line, which is the command you used the
+last time you did @kbd{M-x compile}. If you type just @key{RET}, the
+same command line is used again. For the first @kbd{M-x compile}, the
+default is @samp{make -k}, which is correct most of the time for
+nontrivial programs. (@xref{Top,, Make, make, GNU Make Manual}.)
+The default compilation command comes from the variable
@code{compile-command}; if the appropriate compilation command for a
file is something other than @samp{make -k}, it can be useful for the
file to specify a local value for @code{compile-command} (@pxref{File
follow output as it comes in.
@findex kill-compilation
- To kill the compilation process, do @kbd{M-x kill-compilation}. When
-the compiler process terminates, the mode line of the
-@samp{*compilation*} buffer changes to say @samp{signal} instead of
-@samp{run}. Starting a new compilation also kills any running
-compilation, as only one can exist at any time. However, @kbd{M-x
-compile} asks for confirmation before actually killing a compilation
-that is running.
+ When the compiler process terminates, for whatever reason, the mode
+line of the @samp{*compilation*} buffer changes to say @samp{signal}
+instead of @samp{run}. Starting a new compilation also kills any
+running compilation, as only one can exist at any time. However,
+@kbd{M-x compile} asks for confirmation before actually killing a
+compilation that is running. You can also kill the compilation
+process with @kbd{M-x kill-compilation}.
@findex recompile
To rerun the last compilation with the same command, type @kbd{M-x
recompile}. This automatically reuses the compilation command from the
last invocation of @kbd{M-x compile}.
+ Emacs does not expect a compiler process to launch asynchronous
+subprocesses; if it does, and they keep running after the main
+compiler process has terminated, Emacs may kill them or their output
+may not arrive in Emacs. To avoid this problem, make the main process
+wait for its subprocesses to finish. In a shell script, you can do this
+using @samp{$!} and @samp{wait}, like this:
+
+@example
+(sleep 10; echo 2nd)& pid=$! # @r{Record pid of subprocess}
+echo first message
+wait $pid # @r{Wait for subprocess}
+@end example
+
+ If the background process does not output to the compilation buffer,
+so you only need to prevent it from being killed when the main
+compilation process terminates, this is sufficient:
+
+@example
+nohup @var{command}; sleep 1
+@end example
+
+@vindex compilation-environment
+ You can control the environment passed to the compilation command
+with the variable @code{compilation-environment}. Its value is a list
+of environment variable settings; each element should be a string of
+the form @code{"@var{envvarname}=@var{value}"}. These environment
+variable settings override the usual ones.
+
@node Grep Searching
@section Searching with Grep under Emacs
buffer and finds no more error messages to visit, it fails and signals
an Emacs error.
+ You don't have to be in the compilation buffer in order to use
+@code{next-error}. If one window on the selected frame can be the
+target of the @code{next-error} call, it is used. Else, if a buffer
+previously had @code{next-error} called on it, it is used. Else,
+if the current buffer can be the target of @code{next-error}, it is
+used. Else, all the buffers Emacs manages are tried for
+@code{next-error} support.
+
@kbd{C-u C-x `} starts scanning from the beginning of the compilation
buffer. This is one way to process the same set of errors again.
The GUD (Grand Unified Debugger) library provides an interface to
various symbolic debuggers from within Emacs. We recommend the debugger
GDB, which is free software, but you can also run DBX, SDB or XDB if you
-have them. GUD can also serve as an interface to the Perl's debugging
+have them. GUD can also serve as an interface to Perl's debugging
mode, the Python debugger PDB, and to JDB, the Java Debugger.
-@xref{Debugger,, The Lisp Debugger, elisp, the Emacs Lisp Reference Manual},
+@xref{Debugging,, The Lisp Debugger, elisp, the Emacs Lisp Reference Manual},
for information on debugging Emacs Lisp programs.
@menu
* Commands of GUD:: Key bindings for common commands.
* GUD Customization:: Defining your own commands for GUD.
* GUD Tooltips:: Showing variable values by pointing with the mouse.
+* GDB Graphical Interface:: An enhanced mode that uses GDB features to
+ implement a graphical debugging environment through
+ Emacs.
@end menu
@node Starting GUD
@table @kbd
@item M-x gdb @key{RET} @var{file} @key{RET}
@findex gdb
-Run GDB as a subprocess of Emacs. This command creates a buffer
+Run GDB as a subprocess of Emacs. If the variable
+@code{gud-gdb-command-name} is ``gdb --annotate=3'' (the default
+value) then GDB starts as for @kbd{M-x gdba} below. If you want GDB
+to start as in Emacs 21.3 and earlier then edit the string in the
+minibuffer or set @code{gud-gdb-command-name} to ``gdb --fullname''.
+You need to do this if you want to run multiple debugging sessions
+within one Emacs session. In this case, the command creates a buffer
for input and output to GDB, and switches to it. If a GDB buffer
already exists, it just switches to that buffer.
+@item M-x gdba @key{RET} @var{file} @key{RET}
+Run GDB as a subprocess of Emacs, providing a graphical interface
+to GDB features through Emacs. @xref{GDB Graphical Interface}.
+
@item M-x dbx @key{RET} @var{file} @key{RET}
@findex dbx
Similar, but run DBX instead of GDB.
also provides commands for setting and clearing breakpoints, for
selecting stack frames, and for stepping through the program. These
commands are available both in the GUD buffer and globally, but with
-different key bindings.
+different key bindings. It also has its own toolbar from which you
+can invoke the more common commands by clicking on the appropriate
+icon. This is particularly useful for repetitive commands like
+gud-next and gud-step and allows the user to hide the GUD buffer.
The breakpoint commands are normally used in source file buffers,
because that is the easiest way to specify where to set or clear the
If you are using GDB, these additional key bindings are available:
@table @kbd
+@item C-c C-r
+@kindex C-c C-r @r{(GUD)}
+@itemx C-x C-a C-r
+@findex gud-run
+Start execution of the program (@code{gud-run}).
+
+@item C-c C-u
+@kindex C-c C-u @r{(GUD)}
+@itemx C-x C-a C-u
+@findex gud-until
+Continue execution to the current line. The program will run until
+it hits a breakpoint, terminates, gets a signal that the debugger is
+checking for, or reaches the line on which the cursor currently sits
+(@code{gud-until}).
+
@item @key{TAB}
@kindex TAB @r{(GUD)}
@findex gud-gdb-complete-command
@findex gud-finish
Run the program until the selected stack frame returns (or until it
stops for some other reason).
+
+@item C-x C-a C-j
+@kindex C-x C-a C-j @r{(GUD)}
+@findex gud-jump
+Only useful in a source buffer, (@code{gud-jump}) transfers the
+program's execution point to the current line. In other words, the
+next line that the program executes will be the one where you gave the
+command. If the new execution line is in a different function from
+the previously one, GDB prompts for confirmation since the results may
+be bizarre. See the GDB manual entry regarding @code{jump} for
+details.
@end table
+If you started GDB with the command @code{gdba}, you can click
+@kbd{Mouse-1} on a line of the source buffer, in the fringe or display
+margin, to set a breakpoint there. If a breakpoint already exists on
+that line, this action will remove it.
+(@code{gdb-mouse-toggle-breakpoint}).
+
These commands interpret a numeric argument as a repeat count, when
that makes sense.
the mouse in the GUD buffer or in source buffers with major modes in the
customizable list @code{tooltip-gud-modes}.
+@node GDB Graphical Interface
+@subsection GDB Graphical Interface
+
+@findex gdba
+The command @code{gdba} starts GDB using a graphical interface where
+you view and control the program's data using Emacs windows. You can
+still interact with GDB through the GUD buffer, but the point of this
+mode is that you can do it through menus and clicks, without needing
+to know GDB commands.
+
+@menu
+* Layout:: Control the number of displayed buffers.
+* Breakpoints Buffer:: A breakpoint control panel.
+* Stack Buffer:: Select a frame from the call stack.
+* Watch Expressions:: Monitor variable values in the speedbar.
+* Other Buffers:: Input/output, locals, registers and assembler buffers.
+@end menu
+
+@node Layout
+@subsubsection Layout
+@cindex GDB User Interface layout
+
+@findex gdb-many-windows
+@vindex gdb-many-windows
+
+If the variable @code{gdb-many-windows} is @code{nil} (the default
+value) then gdb just pops up the GUD buffer unless the variable
+@code{gdb-show-main} is non-@code{nil}. In this case it starts with
+two windows: one displaying the GUD buffer and the other with the
+source file with the main routine of the inferior.
+
+If @code{gdb-many-windows} is non-@code{nil}, regardless of the value of
+@code{gdb-show-main}, the layout below will appear unless
+@code{gdb-use-inferior-io-buffer} is @code{nil}. In this case the
+source buffer occupies the full width of the frame.
+
+@multitable @columnfractions .5 .5
+@item GUD buffer (I/O of GDB)
+@tab Locals buffer
+@item
+@tab
+@item Source buffer
+@tab Input/Output (of inferior) buffer
+@item
+@tab
+@item Stack buffer
+@tab Breakpoints buffer
+@end multitable
+
+To toggle this layout, do @kbd{M-x gdb-many-windows}.
+
+@findex gdb-restore-windows
+If you change the window layout, for example, while editing and
+re-compiling your program, then you can restore it with the command
+@code{gdb-restore-windows}.
+
+You may also choose which additional buffers you want to display,
+either in the same frame or a different one. Select GDB-windows or
+GDB-Frames from the menu-bar under the heading GUD. If the menu-bar
+is unavailable, type @code{M-x
+gdb-display-@var{buffertype}-buffer} or @code{M-x
+gdb-frame-@var{buffertype}-buffer} respectively, where @var{buffertype}
+is the relevant buffer type e.g breakpoints.
+
+@node Breakpoints Buffer
+@subsubsection Breakpoints Buffer
+
+The breakpoints buffer shows the existing breakpoints and watchpoints
+(@pxref{Breakpoints,,, gdb, The GNU debugger}). It has three special
+commands:
+
+@table @kbd
+@item @key{SPC}
+@kindex SPC @r{(GDB breakpoints buffer)}
+@findex gdb-toggle-breakpoint
+Enable/disable the breakpoint at the current line
+(@code{gdb-toggle-breakpoint}). On a graphical display, this changes
+the color of a bullet in the margin of the source buffer at the
+relevant line. This is red when the breakpoint is enabled and grey
+when it is disabled. Text-only terminals correspondingly display
+a @samp{B} or @samp{b}.
+
+@item @kbd{d}
+@kindex d @r{(GDB breakpoints buffer)}
+@findex gdb-delete-breakpoint
+Delete the breakpoint at the current line (@code{gdb-delete-breakpoint}).
+
+@item @key{RET}
+@kindex RET @r{(GDB breakpoints buffer)}
+@findex gdb-goto-breakpoint
+Display the file in the source buffer at the breakpoint specified at
+the current line (@code{gdb-goto-breakpoint}). Alternatively, click @kbd{Mouse-2} on the breakpoint that you wish to visit.
+@end table
+
+@node Stack Buffer
+@subsubsection Stack Buffer
+
+The stack buffer displays a @dfn{call stack}, with one line for each
+of the nested subroutine calls (@dfn{stack frames}) now active in the
+program. @xref{Backtrace,,info stack, gdb, The GNU debugger}.
+
+Move point to any frame in the stack and type @key{RET} to make it
+become the current frame (@code{gdb-frames-select}) and display the
+associated source in the source buffer. Alternatively, click
+@kbd{Mouse-2} to make the selected frame become the current one. If the
+locals buffer is displayed then its contents update to display the
+variables that are local to the new frame.
+
+@node Watch Expressions
+@subsubsection Watch Expressions
+@cindex Watching expressions in GDB
+
+If you want to see how a variable changes each time your program stops
+then place the cursor over the variable name and click on the watch
+icon in the toolbar (@code{gud-watch}).
+
+Each watch expression is displayed in the speedbar. Complex data
+types, such as arrays, structures and unions are represented in a tree
+format. To expand or contract a complex data type, click @kbd{Mouse-2}
+on the tag to the left of the expression.
+
+@kindex RET @r{(GDB speedbar)}
+@findex gdb-var-delete
+With the cursor over the root expression of a complex data type, type
+@kbd{D} to delete it from the speedbar
+(@code{gdb-var-delete}).
+
+@findex gdb-edit-value
+With the cursor over a simple data type or an element of a complex
+data type which holds a value, type @key{RET} or click @kbd{Mouse-2} to edit
+its value. A prompt for a new value appears in the mini-buffer
+(@code{gdb-edit-value}).
+
+If you set the variable @code{gdb-show-changed-values} to
+non-@code{nil} (the default value), then Emacs will use
+font-lock-warning-face to display values that have recently changed in
+the speedbar.
+
+If you set the variable @code{gdb-use-colon-colon-notation} to a
+non-@code{nil} value, then, in C, Emacs will use the
+FUNCTION::VARIABLE format to display variables in the speedbar.
+Since this does not work for variables defined in compound statements,
+the default value is @code{nil}.
+
+@node Other Buffers
+@subsubsection Other Buffers
+
+@table @asis
+@item Input/Output Buffer
+If the variable @code{gdb-use-inferior-io-buffer} is non-@code{nil},
+the executable program that is being debugged takes its input and
+displays its output here. Some of the commands from shell mode are
+available here. @xref{Shell Mode}.
+
+@item Locals Buffer
+The locals buffer displays the values of local variables of the
+current frame for simple data types (@pxref{Frame Info,,, gdb, The GNU
+debugger}).
+
+Arrays and structures display their type only. You must display them
+separately to examine their values. @ref{Watch Expressions}.
+
+@item Registers Buffer
+The registers buffer displays the values held by the registers
+(@pxref{Registers,,, gdb, The GNU debugger}).
+
+@item Assembler Buffer
+The assembler buffer displays the current frame as machine code. An
+overlay arrow points to the current instruction and you can set and
+remove breakpoints as with the source buffer. Breakpoints also
+appear in the margin.
+
+@item Threads Buffer
+
+The threads buffer displays a summary of all threads currently in your
+program.(@pxref{Threads,,, gdb, The GNU debugger}). Move point to
+any thread in the list and type @key{RET} to make it become the
+current thread (@code{gdb-threads-select}) and display the associated
+source in the source buffer. Alternatively, click @kbd{Mouse-2} to
+make the selected thread become the current one.
+
+@end table
+
@node Executing Lisp
@section Executing Lisp Expressions
@code{t} if you want to try loading them.
@node Lisp Eval
-@section Evaluating Emacs-Lisp Expressions
+@section Evaluating Emacs Lisp Expressions
@cindex Emacs-Lisp mode
@cindex mode, Emacs-Lisp
Evaluate all the Lisp expressions in the buffer.
@end table
+@ifinfo
+@c This uses ``colon'' instead of a literal `:' because Info cannot
+@c cope with a `:' in a menu
+@kindex M-@key{colon}
+@end ifinfo
+@ifnotinfo
@kindex M-:
+@end ifnotinfo
@findex eval-expression
@kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating
a Lisp expression interactively. It reads the expression using the
variable to the initial value specified in the @code{defvar} expression.
@code{defcustom} expressions are treated similarly.
This special feature is convenient for debugging Lisp programs.
+Typing @kbd{C-M-x} on a @code{defface} expression reinitializes
+the face according to the @code{defface} specification.
@kindex C-x C-e
@findex eval-last-sexp
the function definition that point is in, but the way of doing so is
different according to where the relevant Lisp environment is found.
@xref{Executing Lisp}.
+
+@ignore
+ arch-tag: 9c3c2f71-b332-4144-8500-3ff9945a50ed
+@end ignore