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797 lines
32 KiB
Plaintext
@c This is part of the Emacs manual.
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@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@node Building, Abbrevs, Programs, Top
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@chapter Compiling and Testing Programs
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@cindex building programs
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@cindex program building
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@cindex running Lisp functions
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The previous chapter discusses the Emacs commands that are useful for
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making changes in programs. This chapter deals with commands that assist
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in the larger process of developing and maintaining programs.
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@menu
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* Compilation:: Compiling programs in languages other
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than Lisp (C, Pascal, etc.).
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* Grep Searching:: Running grep as if it were a compiler.
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* Compilation Mode:: The mode for visiting compiler errors.
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* Compilation Shell:: Customizing your shell properly
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for use in the compilation buffer.
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* Debuggers:: Running symbolic debuggers for non-Lisp programs.
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* Executing Lisp:: Various modes for editing Lisp programs,
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with different facilities for running
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the Lisp programs.
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* Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs.
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* Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer.
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* Eval: Lisp Eval. Executing a single Lisp expression in Emacs.
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* External Lisp:: Communicating through Emacs with a separate Lisp.
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@end menu
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@node Compilation
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@section Running Compilations under Emacs
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@cindex inferior process
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@cindex make
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@cindex compilation errors
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@cindex error log
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Emacs can run compilers for noninteractive languages such as C and
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Fortran as inferior processes, feeding the error log into an Emacs buffer.
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It can also parse the error messages and show you the source lines where
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compilation errors occurred.
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@table @kbd
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@item M-x compile
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Run a compiler asynchronously under Emacs, with error messages to
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@samp{*compilation*} buffer.
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@item M-x grep
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Run @code{grep} asynchronously under Emacs, with matching lines
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listed in the buffer named @samp{*grep*}.
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@item M-x grep-find
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Run @code{grep} via @code{find}, with user-specified arguments, and
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collect output in the buffer named @samp{*grep*}.
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@item M-x kill-compilation
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@itemx M-x kill-grep
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Kill the running compilation or @code{grep} subprocess.
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@end table
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@findex compile
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To run @code{make} or another compilation command, do @kbd{M-x
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compile}. This command reads a shell command line using the minibuffer,
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and then executes the command in an inferior shell, putting output in
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the buffer named @samp{*compilation*}. The current buffer's default
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directory is used as the working directory for the execution of the
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command; normally, therefore, the compilation happens in this
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directory.
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@vindex compile-command
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When the shell command line is read, the minibuffer appears containing
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a default command line, which is the command you used the last time you
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did @kbd{M-x compile}. If you type just @key{RET}, the same command
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line is used again. For the first @kbd{M-x compile}, the default is
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@samp{make -k}. The default compilation command comes from the variable
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@code{compile-command}; if the appropriate compilation command for a
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file is something other than @samp{make -k}, it can be useful for the
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file to specify a local value for @code{compile-command} (@pxref{File
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Variables}).
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Starting a compilation displays the buffer @samp{*compilation*} in
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another window but does not select it. The buffer's mode line tells you
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whether compilation is finished, with the word @samp{run} or @samp{exit}
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inside the parentheses. You do not have to keep this buffer visible;
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compilation continues in any case. While a compilation is going on, the
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string @samp{Compiling} appears in the mode lines of all windows. When
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this string disappears, the compilation is finished.
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If you want to watch the compilation transcript as it appears, switch
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to the @samp{*compilation*} buffer and move point to the end of the
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buffer. When point is at the end, new compilation output is inserted
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above point, which remains at the end. If point is not at the end of
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the buffer, it remains fixed while more compilation output is added at
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the end of the buffer.
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@vindex compilation-scroll-output
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If you set the variable @code{compilation-scroll-output} to a
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non-@code{nil} value, then the compilation buffer always scrolls to
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follow output as it comes in.
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@findex kill-compilation
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To kill the compilation process, do @kbd{M-x kill-compilation}. When
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the compiler process terminates, the mode line of the
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@samp{*compilation*} buffer changes to say @samp{signal} instead of
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@samp{run}. Starting a new compilation also kills any running
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compilation, as only one can exist at any time. However, @kbd{M-x
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compile} asks for confirmation before actually killing a compilation
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that is running.
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@node Grep Searching
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@section Searching with Grep under Emacs
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@findex grep
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Just as you can run a compiler from Emacs and then visit the lines
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where there were compilation errors, you can also run @code{grep} and
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then visit the lines on which matches were found. This works by
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treating the matches reported by @code{grep} as if they were ``errors.''
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To do this, type @kbd{M-x grep}, then enter a command line that
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specifies how to run @code{grep}. Use the same arguments you would give
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@code{grep} when running it normally: a @code{grep}-style regexp
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(usually in single-quotes to quote the shell's special characters)
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followed by file names, which may use wildcards. The output from
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@code{grep} goes in the @samp{*grep*} buffer. You can find the
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corresponding lines in the original files using @kbd{C-x `} and
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@key{RET}, as with compilation errors.
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If you specify a prefix argument for @kbd{M-x grep}, it figures out
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the tag (@pxref{Tags}) around point, and puts that into the default
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@code{grep} command.
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@findex grep-find
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The command @kbd{M-x grep-find} is similar to @kbd{M-x grep}, but it
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supplies a different initial default for the command---one that runs
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both @code{find} and @code{grep}, so as to search every file in a
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directory tree. See also the @code{find-grep-dired} command,
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in @ref{Dired and Find}.
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@node Compilation Mode
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@section Compilation Mode
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@findex compile-goto-error
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@cindex Compilation mode
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@cindex mode, Compilation
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The @samp{*compilation*} buffer uses a special major mode, Compilation
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mode, whose main feature is to provide a convenient way to look at the
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source line where the error happened.
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@table @kbd
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@item C-x `
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Visit the locus of the next compiler error message or @code{grep} match.
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@item @key{RET}
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Visit the locus of the error message that point is on.
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This command is used in the compilation buffer.
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@item Mouse-2
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Visit the locus of the error message that you click on.
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@end table
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@kindex C-x `
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@findex next-error
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You can visit the source for any particular error message by moving
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point in @samp{*compilation*} to that error message and typing @key{RET}
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(@code{compile-goto-error}). Or click @kbd{Mouse-2} on the error message;
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you need not switch to the @samp{*compilation*} buffer first.
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To parse the compiler error messages sequentially, type @kbd{C-x `}
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(@code{next-error}). The character following the @kbd{C-x} is the
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backquote or ``grave accent,'' not the single-quote. This command is
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available in all buffers, not just in @samp{*compilation*}; it displays
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the next error message at the top of one window and source location of
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the error in another window.
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The first time @kbd{C-x `} is used after the start of a compilation,
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it moves to the first error's location. Subsequent uses of @kbd{C-x `}
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advance down to subsequent errors. If you visit a specific error
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message with @key{RET} or @kbd{Mouse-2}, subsequent @kbd{C-x `}
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commands advance from there. When @kbd{C-x `} gets to the end of the
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buffer and finds no more error messages to visit, it fails and signals
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an Emacs error.
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@kbd{C-u C-x `} starts scanning from the beginning of the compilation
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buffer. This is one way to process the same set of errors again.
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Compilation mode also redefines the keys @key{SPC} and @key{DEL} to
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scroll by screenfuls, and @kbd{M-n} and @kbd{M-p} to move to the next or
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previous error message. You can also use @kbd{M-@{} and @kbd{M-@}} to
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move up or down to an error message for a different source file.
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The features of Compilation mode are also available in a minor mode
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called Compilation Minor mode. This lets you parse error messages in
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any buffer, not just a normal compilation output buffer. Type @kbd{M-x
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compilation-minor-mode} to enable the minor mode. This defines the keys
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@key{RET} and @kbd{Mouse-2}, as in the Compilation major mode.
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Compilation minor mode works in any buffer, as long as the contents
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are in a format that it understands. In an Rlogin buffer (@pxref{Remote
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Host}), Compilation minor mode automatically accesses remote source
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files by FTP (@pxref{File Names}).
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@node Compilation Shell
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@section Subshells for Compilation
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Emacs uses a shell to run the compilation command, but specifies
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the option for a noninteractive shell. This means, in particular, that
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the shell should start with no prompt. If you find your usual shell
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prompt making an unsightly appearance in the @samp{*compilation*}
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buffer, it means you have made a mistake in your shell's init file by
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setting the prompt unconditionally. (This init file's name may be
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@file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or various
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other things, depending on the shell you use.) The shell init file
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should set the prompt only if there already is a prompt. In csh, here
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is how to do it:
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@example
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if ($?prompt) set prompt = @dots{}
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@end example
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@noindent
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And here's how to do it in bash:
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@example
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if [ "$@{PS1+set@}" = set ]
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then PS1=@dots{}
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fi
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@end example
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There may well be other things that your shell's init file
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ought to do only for an interactive shell. You can use the same
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method to conditionalize them.
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The MS-DOS ``operating system'' does not support asynchronous
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subprocesses; to work around this lack, @kbd{M-x compile} runs the
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compilation command synchronously on MS-DOS. As a consequence, you must
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wait until the command finishes before you can do anything else in
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Emacs. @xref{MS-DOS}.
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@node Debuggers
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@section Running Debuggers Under Emacs
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@cindex debuggers
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@cindex GUD library
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@cindex GDB
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@cindex DBX
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@cindex SDB
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@cindex XDB
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@cindex Perldb
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@cindex JDB
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@cindex PDB
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@c Do you believe in GUD?
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The GUD (Grand Unified Debugger) library provides an interface to
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various symbolic debuggers from within Emacs. We recommend the debugger
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GDB, which is free software, but you can also run DBX, SDB or XDB if you
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have them. GUD can also serve as an interface to the Perl's debugging
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mode, the Python debugger PDB, and to JDB, the Java Debugger.
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@menu
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* Starting GUD:: How to start a debugger subprocess.
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* Debugger Operation:: Connection between the debugger and source buffers.
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* Commands of GUD:: Key bindings for common commands.
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* GUD Customization:: Defining your own commands for GUD.
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@end menu
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@node Starting GUD
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@subsection Starting GUD
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There are several commands for starting a debugger, each corresponding
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to a particular debugger program.
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@table @kbd
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@item M-x gdb @key{RET} @var{file} @key{RET}
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@findex gdb
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Run GDB as a subprocess of Emacs. This command creates a buffer for
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input and output to GDB, and switches to it. If a GDB buffer already
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exists, it just switches to that buffer.
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@item M-x dbx @key{RET} @var{file} @key{RET}
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@findex dbx
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Similar, but run DBX instead of GDB.
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@item M-x xdb @key{RET} @var{file} @key{RET}
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@findex xdb
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@vindex gud-xdb-directories
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Similar, but run XDB instead of GDB. Use the variable
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@code{gud-xdb-directories} to specify directories to search for source
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files.
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@item M-x sdb @key{RET} @var{file} @key{RET}
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@findex sdb
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Similar, but run SDB instead of GDB.
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Some versions of SDB do not mention source file names in their
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messages. When you use them, you need to have a valid tags table
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(@pxref{Tags}) in order for GUD to find functions in the source code.
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If you have not visited a tags table or the tags table doesn't list one
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of the functions, you get a message saying @samp{The sdb support
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requires a valid tags table to work}. If this happens, generate a valid
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tags table in the working directory and try again.
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@item M-x perldb @key{RET} @var{file} @key{RET}
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@findex perldb
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Run the Perl interpreter in debug mode to debug @var{file}, a Perl program.
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@item M-x jdb @key{RET} @var{file} @key{RET}
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@findex jdb
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Run the Java debugger to debug @var{file}.
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@item M-x pdb @key{RET} @var{file} @key{RET}
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@findex pdb
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Run the Python debugger to debug @var{file}.
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@end table
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Each of these commands takes one argument: a command line to invoke
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the debugger. In the simplest case, specify just the name of the
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executable file you want to debug. You may also use options that the
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debugger supports. However, shell wildcards and variables are not
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allowed. GUD assumes that the first argument not starting with a
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@samp{-} is the executable file name.
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Emacs can only run one debugger process at a time.
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@node Debugger Operation
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@subsection Debugger Operation
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When you run a debugger with GUD, the debugger uses an Emacs buffer
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for its ordinary input and output. This is called the GUD buffer. The
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debugger displays the source files of the program by visiting them in
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Emacs buffers. An arrow (@samp{=>}) in one of these buffers indicates
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the current execution line. Moving point in this buffer does not move
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the arrow.
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You can start editing these source files at any time in the buffers
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that were made to display them. The arrow is not part of the file's
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text; it appears only on the screen. If you do modify a source file,
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keep in mind that inserting or deleting lines will throw off the arrow's
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positioning; GUD has no way of figuring out which line corresponded
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before your changes to the line number in a debugger message. Also,
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you'll typically have to recompile and restart the program for your
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changes to be reflected in the debugger's tables.
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If you wish, you can control your debugger process entirely through the
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debugger buffer, which uses a variant of Shell mode. All the usual
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commands for your debugger are available, and you can use the Shell mode
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history commands to repeat them. @xref{Shell Mode}.
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@node Commands of GUD
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@subsection Commands of GUD
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The GUD interaction buffer uses a variant of Shell mode, so the
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commands of Shell mode are available (@pxref{Shell Mode}). GUD mode
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also provides commands for setting and clearing breakpoints, for
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selecting stack frames, and for stepping through the program. These
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commands are available both in the GUD buffer and globally, but with
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different key bindings.
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The breakpoint commands are usually used in source file buffers,
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because that is the way to specify where to set or clear the breakpoint.
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Here's the global command to set a breakpoint:
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@table @kbd
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@item C-x @key{SPC}
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@kindex C-x SPC
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Set a breakpoint on the source line that point is on.
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@end table
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@kindex C-x C-a @r{(GUD)}
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Here are the other special commands provided by GUD. The keys
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starting with @kbd{C-c} are available only in the GUD interaction
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buffer. The key bindings that start with @kbd{C-x C-a} are available in
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the GUD interaction buffer and also in source files.
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@table @kbd
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@item C-c C-l
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@kindex C-c C-l @r{(GUD)}
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@itemx C-x C-a C-l
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@findex gud-refresh
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Display in another window the last line referred to in the GUD
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buffer (that is, the line indicated in the last location message).
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This runs the command @code{gud-refresh}.
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@item C-c C-s
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@kindex C-c C-s @r{(GUD)}
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@itemx C-x C-a C-s
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@findex gud-step
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Execute a single line of code (@code{gud-step}). If the line contains
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a function call, execution stops after entering the called function.
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@item C-c C-n
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@kindex C-c C-n @r{(GUD)}
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@itemx C-x C-a C-n
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@findex gud-next
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Execute a single line of code, stepping across entire function calls
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at full speed (@code{gud-next}).
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@item C-c C-i
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@kindex C-c C-i @r{(GUD)}
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@itemx C-x C-a C-i
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@findex gud-stepi
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Execute a single machine instruction (@code{gud-stepi}).
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@need 3000
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@item C-c C-r
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@kindex C-c C-r @r{(GUD)}
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@itemx C-x C-a C-r
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@findex gud-cont
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Continue execution without specifying any stopping point. The program
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will run until it hits a breakpoint, terminates, or gets a signal that
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the debugger is checking for (@code{gud-cont}).
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@need 1000
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@item C-c C-d
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@kindex C-c C-d @r{(GUD)}
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@itemx C-x C-a C-d
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@findex gud-remove
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Delete the breakpoint(s) on the current source line, if any
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(@code{gud-remove}). If you use this command in the GUD interaction
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buffer, it applies to the line where the program last stopped.
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@item C-c C-t
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@kindex C-c C-t @r{(GUD)}
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@itemx C-x C-a C-t
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@findex gud-tbreak
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Set a temporary breakpoint on the current source line, if any.
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If you use this command in the GUD interaction buffer,
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it applies to the line where the program last stopped.
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@end table
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The above commands are common to all supported debuggers. If you are
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using GDB or (some versions of) DBX, these additional commands are available:
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@table @kbd
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@item C-c <
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@kindex C-c < @r{(GUD)}
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@itemx C-x C-a <
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@findex gud-up
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Select the next enclosing stack frame (@code{gud-up}). This is
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equivalent to the @samp{up} command.
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@item C-c >
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@kindex C-c > @r{(GUD)}
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@itemx C-x C-a >
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@findex gud-down
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Select the next inner stack frame (@code{gud-down}). This is
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equivalent to the @samp{down} command.
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@end table
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If you are using GDB, these additional key bindings are available:
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@table @kbd
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@item @key{TAB}
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@kindex TAB @r{(GUD)}
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@findex gud-gdb-complete-command
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With GDB, complete a symbol name (@code{gud-gdb-complete-command}).
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This key is available only in the GUD interaction buffer, and requires
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GDB versions 4.13 and later.
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@item C-c C-f
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@kindex C-c C-f @r{(GUD)}
|
|
@itemx C-x C-a C-f
|
|
@findex gud-finish
|
|
Run the program until the selected stack frame returns (or until it
|
|
stops for some other reason).
|
|
@end table
|
|
|
|
These commands interpret a numeric argument as a repeat count, when
|
|
that makes sense.
|
|
|
|
Because @key{TAB} serves as a completion command, you can't use it to
|
|
enter a tab as input to the program you are debugging with GDB.
|
|
Instead, type @kbd{C-q @key{TAB}} to enter a tab.
|
|
|
|
@node GUD Customization
|
|
@subsection GUD Customization
|
|
|
|
@vindex gdb-mode-hook
|
|
@vindex dbx-mode-hook
|
|
@vindex sdb-mode-hook
|
|
@vindex xdb-mode-hook
|
|
@vindex perldb-mode-hook
|
|
@vindex pdb-mode-hook
|
|
@vindex jdb-mode-hook
|
|
On startup, GUD runs one of the following hooks: @code{gdb-mode-hook},
|
|
if you are using GDB; @code{dbx-mode-hook}, if you are using DBX;
|
|
@code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you
|
|
are using XDB; @code{perldb-mode-hook}, for Perl debugging mode;
|
|
@code{jdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB. You can
|
|
use these hooks to define custom key bindings for the debugger
|
|
interaction buffer. @xref{Hooks}.
|
|
|
|
Here is a convenient way to define a command that sends a particular
|
|
command string to the debugger, and set up a key binding for it in the
|
|
debugger interaction buffer:
|
|
|
|
@findex gud-def
|
|
@example
|
|
(gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring})
|
|
@end example
|
|
|
|
This defines a command named @var{function} which sends
|
|
@var{cmdstring} to the debugger process, and gives it the documentation
|
|
string @var{docstring}. You can use the command thus defined in any
|
|
buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds
|
|
the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to
|
|
@kbd{C-x C-a @var{binding}} generally.
|
|
|
|
The command string @var{cmdstring} may contain certain
|
|
@samp{%}-sequences that stand for data to be filled in at the time
|
|
@var{function} is called:
|
|
|
|
@table @samp
|
|
@item %f
|
|
The name of the current source file. If the current buffer is the GUD
|
|
buffer, then the ``current source file'' is the file that the program
|
|
stopped in.
|
|
@c This said, ``the name of the file the program counter was in at the last breakpoint.''
|
|
@c But I suspect it is really the last stop file.
|
|
|
|
@item %l
|
|
The number of the current source line. If the current buffer is the GUD
|
|
buffer, then the ``current source line'' is the line that the program
|
|
stopped in.
|
|
|
|
@item %e
|
|
The text of the C lvalue or function-call expression at or adjacent to point.
|
|
|
|
@item %a
|
|
The text of the hexadecimal address at or adjacent to point.
|
|
|
|
@item %p
|
|
The numeric argument of the called function, as a decimal number. If
|
|
the command is used without a numeric argument, @samp{%p} stands for the
|
|
empty string.
|
|
|
|
If you don't use @samp{%p} in the command string, the command you define
|
|
ignores any numeric argument.
|
|
@end table
|
|
|
|
@node Executing Lisp
|
|
@section Executing Lisp Expressions
|
|
|
|
Emacs has several different major modes for Lisp and Scheme. They are
|
|
the same in terms of editing commands, but differ in the commands for
|
|
executing Lisp expressions. Each mode has its own purpose.
|
|
|
|
@table @asis
|
|
@item Emacs-Lisp mode
|
|
The mode for editing source files of programs to run in Emacs Lisp.
|
|
This mode defines @kbd{C-M-x} to evaluate the current defun.
|
|
@xref{Lisp Libraries}.
|
|
@item Lisp Interaction mode
|
|
The mode for an interactive session with Emacs Lisp. It defines
|
|
@kbd{C-j} to evaluate the sexp before point and insert its value in the
|
|
buffer. @xref{Lisp Interaction}.
|
|
@item Lisp mode
|
|
The mode for editing source files of programs that run in Lisps other
|
|
than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun
|
|
to an inferior Lisp process. @xref{External Lisp}.
|
|
@item Inferior Lisp mode
|
|
The mode for an interactive session with an inferior Lisp process.
|
|
This mode combines the special features of Lisp mode and Shell mode
|
|
(@pxref{Shell Mode}).
|
|
@item Scheme mode
|
|
Like Lisp mode but for Scheme programs.
|
|
@item Inferior Scheme mode
|
|
The mode for an interactive session with an inferior Scheme process.
|
|
@end table
|
|
|
|
Most editing commands for working with Lisp programs are in fact
|
|
available globally. @xref{Programs}.
|
|
|
|
@node Lisp Libraries
|
|
@section Libraries of Lisp Code for Emacs
|
|
@cindex libraries
|
|
@cindex loading Lisp code
|
|
|
|
Lisp code for Emacs editing commands is stored in files whose names
|
|
conventionally end in @file{.el}. This ending tells Emacs to edit them in
|
|
Emacs-Lisp mode (@pxref{Executing Lisp}).
|
|
|
|
@findex load-file
|
|
To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This
|
|
command reads a file name using the minibuffer and then executes the
|
|
contents of that file as Lisp code. It is not necessary to visit the
|
|
file first; in any case, this command reads the file as found on disk,
|
|
not text in an Emacs buffer.
|
|
|
|
@findex load
|
|
@findex load-library
|
|
Once a file of Lisp code is installed in the Emacs Lisp library
|
|
directories, users can load it using @kbd{M-x load-library}. Programs can
|
|
load it by calling @code{load-library}, or with @code{load}, a more primitive
|
|
function that is similar but accepts some additional arguments.
|
|
|
|
@kbd{M-x load-library} differs from @kbd{M-x load-file} in that it
|
|
searches a sequence of directories and tries three file names in each
|
|
directory. Suppose your argument is @var{lib}; the three names are
|
|
@file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just
|
|
@file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention
|
|
the result of compiling @file{@var{lib}.el}; it is better to load the
|
|
compiled file, since it will load and run faster.
|
|
|
|
If @code{load-library} finds that @file{@var{lib}.el} is newer than
|
|
@file{@var{lib}.elc} file, it prints a warning, because it's likely that
|
|
somebody made changes to the @file{.el} file and forgot to recompile
|
|
it.
|
|
|
|
Because the argument to @code{load-library} is usually not in itself
|
|
a valid file name, file name completion is not available. Indeed, when
|
|
using this command, you usually do not know exactly what file name
|
|
will be used.
|
|
|
|
@vindex load-path
|
|
The sequence of directories searched by @kbd{M-x load-library} is
|
|
specified by the variable @code{load-path}, a list of strings that are
|
|
directory names. The default value of the list contains the directory where
|
|
the Lisp code for Emacs itself is stored. If you have libraries of
|
|
your own, put them in a single directory and add that directory
|
|
to @code{load-path}. @code{nil} in this list stands for the current default
|
|
directory, but it is probably not a good idea to put @code{nil} in the
|
|
list. If you find yourself wishing that @code{nil} were in the list,
|
|
most likely what you really want to do is use @kbd{M-x load-file}
|
|
this once.
|
|
|
|
@cindex autoload
|
|
Often you do not have to give any command to load a library, because
|
|
the commands defined in the library are set up to @dfn{autoload} that
|
|
library. Trying to run any of those commands calls @code{load} to load
|
|
the library; this replaces the autoload definitions with the real ones
|
|
from the library.
|
|
|
|
@cindex byte code
|
|
Emacs Lisp code can be compiled into byte-code which loads faster,
|
|
takes up less space when loaded, and executes faster. @xref{Byte
|
|
Compilation,, Byte Compilation, elisp, the Emacs Lisp Reference Manual}.
|
|
By convention, the compiled code for a library goes in a separate file
|
|
whose name consists of the library source file with @samp{c} appended.
|
|
Thus, the compiled code for @file{foo.el} goes in @file{foo.elc}.
|
|
That's why @code{load-library} searches for @samp{.elc} files first.
|
|
|
|
@node Lisp Eval
|
|
@section Evaluating Emacs-Lisp Expressions
|
|
@cindex Emacs-Lisp mode
|
|
@cindex mode, Emacs-Lisp
|
|
|
|
@findex emacs-lisp-mode
|
|
Lisp programs intended to be run in Emacs should be edited in
|
|
Emacs-Lisp mode; this happens automatically for file names ending in
|
|
@file{.el}. By contrast, Lisp mode itself is used for editing Lisp
|
|
programs intended for other Lisp systems. To switch to Emacs-Lisp mode
|
|
explicitly, use the command @kbd{M-x emacs-lisp-mode}.
|
|
|
|
For testing of Lisp programs to run in Emacs, it is often useful to
|
|
evaluate part of the program as it is found in the Emacs buffer. For
|
|
example, after changing the text of a Lisp function definition,
|
|
evaluating the definition installs the change for future calls to the
|
|
function. Evaluation of Lisp expressions is also useful in any kind of
|
|
editing, for invoking noninteractive functions (functions that are
|
|
not commands).
|
|
|
|
@table @kbd
|
|
@item M-:
|
|
Read a single Lisp expression in the minibuffer, evaluate it, and print
|
|
the value in the echo area (@code{eval-expression}).
|
|
@item C-x C-e
|
|
Evaluate the Lisp expression before point, and print the value in the
|
|
echo area (@code{eval-last-sexp}).
|
|
@item C-M-x
|
|
Evaluate the defun containing or after point, and print the value in
|
|
the echo area (@code{eval-defun}).
|
|
@item M-x eval-region
|
|
Evaluate all the Lisp expressions in the region.
|
|
@item M-x eval-current-buffer
|
|
Evaluate all the Lisp expressions in the buffer.
|
|
@end table
|
|
|
|
@kindex M-:
|
|
@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
|
|
minibuffer, so you can execute any expression on a buffer regardless of
|
|
what the buffer contains. When the expression is evaluated, the current
|
|
buffer is once again the buffer that was current when @kbd{M-:} was
|
|
typed.
|
|
|
|
@kindex C-M-x @r{(Emacs-Lisp mode)}
|
|
@findex eval-defun
|
|
In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command
|
|
@code{eval-defun}, which parses the defun containing or following point
|
|
as a Lisp expression and evaluates it. The value is printed in the echo
|
|
area. This command is convenient for installing in the Lisp environment
|
|
changes that you have just made in the text of a function definition.
|
|
|
|
@kbd{C-M-x} treats @code{defvar} expressions specially. Normally,
|
|
evaluating a @code{defvar} expression does nothing if the variable it
|
|
defines already has a value. But @kbd{C-M-x} unconditionally resets the
|
|
variable to the initial value specified in the @code{defvar} expression.
|
|
This special feature is convenient for debugging Lisp programs.
|
|
|
|
@kindex C-x C-e
|
|
@findex eval-last-sexp
|
|
The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp
|
|
expression preceding point in the buffer, and displays the value in the
|
|
echo area. It is available in all major modes, not just Emacs-Lisp
|
|
mode. It does not treat @code{defvar} specially.
|
|
|
|
If @kbd{C-M-x}, @kbd{C-x C-e}, or @kbd{M-:} is given a numeric
|
|
argument, it inserts the value into the current buffer at point, rather
|
|
than displaying it in the echo area. The argument's value does not
|
|
matter.
|
|
|
|
@findex eval-region
|
|
@findex eval-current-buffer
|
|
The most general command for evaluating Lisp expressions from a buffer
|
|
is @code{eval-region}. @kbd{M-x eval-region} parses the text of the
|
|
region as one or more Lisp expressions, evaluating them one by one.
|
|
@kbd{M-x eval-current-buffer} is similar but evaluates the entire
|
|
buffer. This is a reasonable way to install the contents of a file of
|
|
Lisp code that you are just ready to test. Later, as you find bugs and
|
|
change individual functions, use @kbd{C-M-x} on each function that you
|
|
change. This keeps the Lisp world in step with the source file.
|
|
|
|
@node Lisp Interaction
|
|
@section Lisp Interaction Buffers
|
|
|
|
The buffer @samp{*scratch*} which is selected when Emacs starts up is
|
|
provided for evaluating Lisp expressions interactively inside Emacs.
|
|
|
|
The simplest way to use the @samp{*scratch*} buffer is to insert Lisp
|
|
expressions and type @kbd{C-j} after each expression. This command
|
|
reads the Lisp expression before point, evaluates it, and inserts the
|
|
value in printed representation before point. The result is a complete
|
|
typescript of the expressions you have evaluated and their values.
|
|
|
|
The @samp{*scratch*} buffer's major mode is Lisp Interaction mode, which
|
|
is the same as Emacs-Lisp mode except for the binding of @kbd{C-j}.
|
|
|
|
@findex lisp-interaction-mode
|
|
The rationale for this feature is that Emacs must have a buffer when
|
|
it starts up, but that buffer is not useful for editing files since a
|
|
new buffer is made for every file that you visit. The Lisp interpreter
|
|
typescript is the most useful thing I can think of for the initial
|
|
buffer to do. Type @kbd{M-x lisp-interaction-mode} to put the current
|
|
buffer in Lisp Interaction mode.
|
|
|
|
@findex ielm
|
|
An alternative way of evaluating Emacs Lisp expressions interactively
|
|
is to use Inferior Emacs-Lisp mode, which provides an interface rather
|
|
like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp
|
|
expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer
|
|
which uses this mode.
|
|
|
|
@node External Lisp
|
|
@section Running an External Lisp
|
|
|
|
Emacs has facilities for running programs in other Lisp systems. You can
|
|
run a Lisp process as an inferior of Emacs, and pass expressions to it to
|
|
be evaluated. You can also pass changed function definitions directly from
|
|
the Emacs buffers in which you edit the Lisp programs to the inferior Lisp
|
|
process.
|
|
|
|
@findex run-lisp
|
|
@vindex inferior-lisp-program
|
|
@kindex C-x C-z
|
|
To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs
|
|
the program named @code{lisp}, the same program you would run by typing
|
|
@code{lisp} as a shell command, with both input and output going through
|
|
an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal
|
|
output'' from Lisp will go into the buffer, advancing point, and any
|
|
``terminal input'' for Lisp comes from text in the buffer. (You can
|
|
change the name of the Lisp executable file by setting the variable
|
|
@code{inferior-lisp-program}.)
|
|
|
|
To give input to Lisp, go to the end of the buffer and type the input,
|
|
terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp
|
|
mode, which combines the special characteristics of Lisp mode with most
|
|
of the features of Shell mode (@pxref{Shell Mode}). The definition of
|
|
@key{RET} to send a line to a subprocess is one of the features of Shell
|
|
mode.
|
|
|
|
@findex lisp-mode
|
|
For the source files of programs to run in external Lisps, use Lisp
|
|
mode. This mode can be selected with @kbd{M-x lisp-mode}, and is used
|
|
automatically for files whose names end in @file{.l}, @file{.lsp}, or
|
|
@file{.lisp}, as most Lisp systems usually expect.
|
|
|
|
@kindex C-M-x @r{(Lisp mode)}
|
|
@findex lisp-eval-defun
|
|
When you edit a function in a Lisp program you are running, the easiest
|
|
way to send the changed definition to the inferior Lisp process is the key
|
|
@kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun},
|
|
which finds the defun around or following point and sends it as input to
|
|
the Lisp process. (Emacs can send input to any inferior process regardless
|
|
of what buffer is current.)
|
|
|
|
Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing programs
|
|
to be run in another Lisp system) and Emacs-Lisp mode (for editing Lisp
|
|
programs to be run in Emacs): in both modes it has the effect of installing
|
|
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}.
|