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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
739a80b3 | 2 | @c Copyright (C) 1985,86,87,93,94,95,97,2000,2001 Free Software Foundation, Inc. |
6bf7aab6 | 3 | @c See file emacs.texi for copying conditions. |
ffb1af2b | 4 | @node Building, Maintaining, Programs, Top |
6bf7aab6 DL |
5 | @chapter Compiling and Testing Programs |
6 | @cindex building programs | |
7 | @cindex program building | |
8 | @cindex running Lisp functions | |
9 | ||
10 | The previous chapter discusses the Emacs commands that are useful for | |
11 | making changes in programs. This chapter deals with commands that assist | |
12 | in the larger process of developing and maintaining programs. | |
13 | ||
14 | @menu | |
15 | * Compilation:: Compiling programs in languages other | |
16 | than Lisp (C, Pascal, etc.). | |
6bf7aab6 DL |
17 | * Compilation Mode:: The mode for visiting compiler errors. |
18 | * Compilation Shell:: Customizing your shell properly | |
19 | for use in the compilation buffer. | |
ed4389af | 20 | * Grep Searching:: Searching with grep. |
ff994d96 | 21 | * Flymake:: Finding syntax errors on the fly. |
177c0ea7 JB |
22 | * Debuggers:: Running symbolic debuggers for non-Lisp programs. |
23 | * Executing Lisp:: Various modes for editing Lisp programs, | |
6bf7aab6 | 24 | with different facilities for running |
177c0ea7 | 25 | the Lisp programs. |
6bf7aab6 | 26 | * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. |
6bf7aab6 | 27 | * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. |
254196f5 | 28 | * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. |
177c0ea7 | 29 | * External Lisp:: Communicating through Emacs with a separate Lisp. |
6bf7aab6 DL |
30 | @end menu |
31 | ||
32 | @node Compilation | |
33 | @section Running Compilations under Emacs | |
34 | @cindex inferior process | |
35 | @cindex make | |
36 | @cindex compilation errors | |
37 | @cindex error log | |
38 | ||
39 | Emacs can run compilers for noninteractive languages such as C and | |
40 | Fortran as inferior processes, feeding the error log into an Emacs buffer. | |
41 | It can also parse the error messages and show you the source lines where | |
42 | compilation errors occurred. | |
43 | ||
44 | @table @kbd | |
45 | @item M-x compile | |
74b1aac1 | 46 | Run a compiler asynchronously under Emacs, with error messages going to |
58fa012d | 47 | the @samp{*compilation*} buffer. |
9ee31341 EZ |
48 | @item M-x recompile |
49 | Invoke a compiler with the same command as in the last invocation of | |
50 | @kbd{M-x compile}. | |
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51 | @item M-x grep |
52 | Run @code{grep} asynchronously under Emacs, with matching lines | |
53 | listed in the buffer named @samp{*grep*}. | |
54 | @item M-x grep-find | |
3d4d788a | 55 | @item M-x find-grep |
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56 | Run @code{grep} via @code{find}, with user-specified arguments, and |
57 | collect output in the buffer named @samp{*grep*}. | |
58 | @item M-x kill-compilation | |
59 | @itemx M-x kill-grep | |
60 | Kill the running compilation or @code{grep} subprocess. | |
61 | @end table | |
62 | ||
63 | @findex compile | |
64 | To run @code{make} or another compilation command, do @kbd{M-x | |
65 | compile}. This command reads a shell command line using the minibuffer, | |
66 | and then executes the command in an inferior shell, putting output in | |
67 | the buffer named @samp{*compilation*}. The current buffer's default | |
68 | directory is used as the working directory for the execution of the | |
69 | command; normally, therefore, the compilation happens in this | |
70 | directory. | |
71 | ||
72 | @vindex compile-command | |
49ba5d16 RS |
73 | When the shell command line is read, the minibuffer appears |
74 | containing a default command line, which is the command you used the | |
75 | last time you did @kbd{M-x compile}. If you type just @key{RET}, the | |
76 | same command line is used again. For the first @kbd{M-x compile}, the | |
77 | default is @samp{make -k}, which is correct most of the time for | |
333c5fc5 | 78 | nontrivial programs. (@xref{Top,, Make, make, GNU Make Manual}.) |
49ba5d16 | 79 | The default compilation command comes from the variable |
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80 | @code{compile-command}; if the appropriate compilation command for a |
81 | file is something other than @samp{make -k}, it can be useful for the | |
82 | file to specify a local value for @code{compile-command} (@pxref{File | |
83 | Variables}). | |
84 | ||
85 | Starting a compilation displays the buffer @samp{*compilation*} in | |
91f1fd02 RS |
86 | another window but does not select it. The buffer's mode line tells |
87 | you whether compilation is finished, with the word @samp{run}, | |
88 | @samp{signal} or @samp{exit} inside the parentheses. You do not have | |
89 | to keep this buffer visible; compilation continues in any case. While | |
90 | a compilation is going on, the string @samp{Compiling} appears in the | |
91 | mode lines of all windows. When this string disappears, the | |
92 | compilation is finished. | |
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93 | |
94 | If you want to watch the compilation transcript as it appears, switch | |
95 | to the @samp{*compilation*} buffer and move point to the end of the | |
96 | buffer. When point is at the end, new compilation output is inserted | |
97 | above point, which remains at the end. If point is not at the end of | |
98 | the buffer, it remains fixed while more compilation output is added at | |
99 | the end of the buffer. | |
100 | ||
09e58ba6 | 101 | @cindex compilation buffer, keeping current position at the end |
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102 | @vindex compilation-scroll-output |
103 | If you set the variable @code{compilation-scroll-output} to a | |
104 | non-@code{nil} value, then the compilation buffer always scrolls to | |
105 | follow output as it comes in. | |
106 | ||
107 | @findex kill-compilation | |
43b4d3c0 | 108 | When the compiler process terminates, for whatever reason, the mode |
91f1fd02 RS |
109 | line of the @samp{*compilation*} buffer changes to say @samp{exit} |
110 | (followed by the exit code, @samp{[0]} for a normal exit), or | |
111 | @samp{signal} (if a signal terminated the process), instead of | |
112 | @samp{run}. Starting a new compilation also kills any running | |
113 | compilation, as only one can exist at any time. However, @kbd{M-x | |
114 | compile} asks for confirmation before actually killing a compilation | |
115 | that is running. You can also kill the compilation process with | |
116 | @kbd{M-x kill-compilation}. | |
6bf7aab6 | 117 | |
9ee31341 EZ |
118 | @findex recompile |
119 | To rerun the last compilation with the same command, type @kbd{M-x | |
3fce19f1 RS |
120 | recompile}. This automatically reuses the compilation command from |
121 | the last invocation of @kbd{M-x compile}. It also reuses the | |
122 | @samp{*compilation*} buffer and starts the compilation in its default | |
123 | directory, which is the directory in which the previous compilation | |
124 | was started. | |
9ee31341 | 125 | |
43b4d3c0 | 126 | Emacs does not expect a compiler process to launch asynchronous |
266e712e | 127 | subprocesses; if it does, and they keep running after the main |
43b4d3c0 RS |
128 | compiler process has terminated, Emacs may kill them or their output |
129 | may not arrive in Emacs. To avoid this problem, make the main process | |
130 | wait for its subprocesses to finish. In a shell script, you can do this | |
131 | using @samp{$!} and @samp{wait}, like this: | |
132 | ||
133 | @example | |
134 | (sleep 10; echo 2nd)& pid=$! # @r{Record pid of subprocess} | |
135 | echo first message | |
136 | wait $pid # @r{Wait for subprocess} | |
137 | @end example | |
266e712e | 138 | |
9cad1898 RS |
139 | If the background process does not output to the compilation buffer, |
140 | so you only need to prevent it from being killed when the main | |
141 | compilation process terminates, this is sufficient: | |
142 | ||
143 | @example | |
144 | nohup @var{command}; sleep 1 | |
145 | @end example | |
146 | ||
147 | @vindex compilation-environment | |
148 | You can control the environment passed to the compilation command | |
149 | with the variable @code{compilation-environment}. Its value is a list | |
150 | of environment variable settings; each element should be a string of | |
151 | the form @code{"@var{envvarname}=@var{value}"}. These environment | |
152 | variable settings override the usual ones. | |
153 | ||
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154 | @node Compilation Mode |
155 | @section Compilation Mode | |
156 | ||
157 | @findex compile-goto-error | |
158 | @cindex Compilation mode | |
159 | @cindex mode, Compilation | |
160 | The @samp{*compilation*} buffer uses a special major mode, Compilation | |
161 | mode, whose main feature is to provide a convenient way to look at the | |
162 | source line where the error happened. | |
163 | ||
09e58ba6 EZ |
164 | If you set the variable @code{compilation-scroll-output} to a |
165 | non-@code{nil} value, then the compilation buffer always scrolls to | |
166 | follow output as it comes in. | |
167 | ||
6bf7aab6 | 168 | @table @kbd |
089ed565 KS |
169 | @item M-g M-n |
170 | @itemx M-g n | |
171 | @itemx C-x ` | |
6bf7aab6 | 172 | Visit the locus of the next compiler error message or @code{grep} match. |
089ed565 KS |
173 | @item M-g M-p |
174 | @itemx M-g p | |
175 | Visit the locus of the previous compiler error message or @code{grep} match. | |
6bf7aab6 DL |
176 | @item @key{RET} |
177 | Visit the locus of the error message that point is on. | |
178 | This command is used in the compilation buffer. | |
179 | @item Mouse-2 | |
180 | Visit the locus of the error message that you click on. | |
ed4389af RS |
181 | @item M-n |
182 | Find and highlight the locus of the next error message, without | |
183 | selecting the source buffer. | |
184 | @item M-p | |
185 | Find and highlight the locus of the previous error message, without | |
186 | selecting the source buffer. | |
187 | @item M-@} | |
188 | Move point to the next error for a different file than the current | |
189 | one. | |
190 | @item M-@{ | |
191 | Move point to the previous error for a different file than the current | |
192 | one. | |
193 | @item C-c C-f | |
194 | Toggle Next Error Follow minor mode, which makes cursor motion in the | |
195 | compilation buffer produce automatic source display. | |
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196 | @end table |
197 | ||
089ed565 KS |
198 | @kindex M-g M-n |
199 | @kindex M-g n | |
6bf7aab6 DL |
200 | @kindex C-x ` |
201 | @findex next-error | |
202 | You can visit the source for any particular error message by moving | |
58fa012d EZ |
203 | point in the @samp{*compilation*} buffer to that error message and |
204 | typing @key{RET} (@code{compile-goto-error}). Alternatively, you can | |
205 | click @kbd{Mouse-2} on the error message; you need not switch to the | |
206 | @samp{*compilation*} buffer first. | |
6bf7aab6 | 207 | |
ed4389af | 208 | @vindex next-error-highlight |
6bf7aab6 DL |
209 | To parse the compiler error messages sequentially, type @kbd{C-x `} |
210 | (@code{next-error}). The character following the @kbd{C-x} is the | |
211 | backquote or ``grave accent,'' not the single-quote. This command is | |
ed4389af RS |
212 | available in all buffers, not just in @samp{*compilation*}; it |
213 | displays the next error message at the top of one window and source | |
214 | location of the error in another window. It also momentarily | |
215 | highlights the relevant source line. You can change the behavior of | |
216 | this highlighting with the variable @code{next-error-highlight}. | |
6bf7aab6 DL |
217 | |
218 | The first time @kbd{C-x `} is used after the start of a compilation, | |
219 | it moves to the first error's location. Subsequent uses of @kbd{C-x `} | |
220 | advance down to subsequent errors. If you visit a specific error | |
221 | message with @key{RET} or @kbd{Mouse-2}, subsequent @kbd{C-x `} | |
222 | commands advance from there. When @kbd{C-x `} gets to the end of the | |
223 | buffer and finds no more error messages to visit, it fails and signals | |
224 | an Emacs error. | |
225 | ||
15658fd8 JL |
226 | You don't have to be in the compilation buffer in order to use |
227 | @code{next-error}. If one window on the selected frame can be the | |
228 | target of the @code{next-error} call, it is used. Else, if a buffer | |
229 | previously had @code{next-error} called on it, it is used. Else, | |
230 | if the current buffer can be the target of @code{next-error}, it is | |
231 | used. Else, all the buffers Emacs manages are tried for | |
232 | @code{next-error} support. | |
233 | ||
6bf7aab6 DL |
234 | @kbd{C-u C-x `} starts scanning from the beginning of the compilation |
235 | buffer. This is one way to process the same set of errors again. | |
236 | ||
0825052e EZ |
237 | @vindex compilation-error-regexp-alist |
238 | @vindex grep-regexp-alist | |
239 | To parse messages from the compiler, Compilation mode uses the | |
240 | variable @code{compilation-error-regexp-alist} which lists various | |
241 | formats of error messages and tells Emacs how to extract the source file | |
242 | and the line number from the text of a message. If your compiler isn't | |
243 | supported, you can tailor Compilation mode to it by adding elements to | |
244 | that list. A similar variable @code{grep-regexp-alist} tells Emacs how | |
245 | to parse output of a @code{grep} command. | |
246 | ||
ed4389af RS |
247 | @findex compilation-next-error |
248 | @findex compilation-previous-error | |
249 | @findex compilation-next-file | |
250 | @findex compilation-previous-file | |
6bf7aab6 | 251 | Compilation mode also redefines the keys @key{SPC} and @key{DEL} to |
ed4389af RS |
252 | scroll by screenfuls, and @kbd{M-n} (@code{compilation-next-error}) |
253 | and @kbd{M-p} (@code{compilation-previous-error}) to move to the next | |
254 | or previous error message. You can also use @kbd{M-@{} | |
255 | (@code{compilation-next-file} and @kbd{M-@}} | |
256 | (@code{compilation-previous-file}) to move up or down to an error | |
257 | message for a different source file. | |
258 | ||
259 | @cindex Next Error Follow mode | |
260 | @findex next-error-follow-minor-mode | |
261 | You can type @kbd{C-c C-f} to toggle Next Error Follow mode. In | |
262 | this minor mode, ordinary cursor motion in the compilation buffer | |
263 | automatically updates the source buffer. For instance, moving the | |
264 | cursor to the next error message causes the location of that error to | |
265 | be displayed immediately. | |
6bf7aab6 DL |
266 | |
267 | The features of Compilation mode are also available in a minor mode | |
268 | called Compilation Minor mode. This lets you parse error messages in | |
269 | any buffer, not just a normal compilation output buffer. Type @kbd{M-x | |
270 | compilation-minor-mode} to enable the minor mode. This defines the keys | |
271 | @key{RET} and @kbd{Mouse-2}, as in the Compilation major mode. | |
272 | ||
273 | Compilation minor mode works in any buffer, as long as the contents | |
274 | are in a format that it understands. In an Rlogin buffer (@pxref{Remote | |
275 | Host}), Compilation minor mode automatically accesses remote source | |
276 | files by FTP (@pxref{File Names}). | |
277 | ||
278 | @node Compilation Shell | |
279 | @section Subshells for Compilation | |
280 | ||
281 | Emacs uses a shell to run the compilation command, but specifies | |
282 | the option for a noninteractive shell. This means, in particular, that | |
283 | the shell should start with no prompt. If you find your usual shell | |
284 | prompt making an unsightly appearance in the @samp{*compilation*} | |
285 | buffer, it means you have made a mistake in your shell's init file by | |
286 | setting the prompt unconditionally. (This init file's name may be | |
287 | @file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or various | |
288 | other things, depending on the shell you use.) The shell init file | |
289 | should set the prompt only if there already is a prompt. In csh, here | |
290 | is how to do it: | |
291 | ||
292 | @example | |
293 | if ($?prompt) set prompt = @dots{} | |
294 | @end example | |
295 | ||
296 | @noindent | |
297 | And here's how to do it in bash: | |
298 | ||
299 | @example | |
300 | if [ "$@{PS1+set@}" = set ] | |
301 | then PS1=@dots{} | |
302 | fi | |
303 | @end example | |
304 | ||
305 | There may well be other things that your shell's init file | |
306 | ought to do only for an interactive shell. You can use the same | |
307 | method to conditionalize them. | |
308 | ||
309 | The MS-DOS ``operating system'' does not support asynchronous | |
310 | subprocesses; to work around this lack, @kbd{M-x compile} runs the | |
311 | compilation command synchronously on MS-DOS. As a consequence, you must | |
312 | wait until the command finishes before you can do anything else in | |
313 | Emacs. @xref{MS-DOS}. | |
314 | ||
ed4389af RS |
315 | @node Grep Searching |
316 | @section Searching with Grep under Emacs | |
317 | ||
318 | @findex grep | |
319 | Just as you can run a compiler from Emacs and then visit the lines | |
320 | where there were compilation errors, you can also run @code{grep} and | |
321 | then visit the lines on which matches were found. This works by | |
322 | treating the matches reported by @code{grep} as if they were ``errors.'' | |
323 | ||
324 | To do this, type @kbd{M-x grep}, then enter a command line that | |
325 | specifies how to run @code{grep}. Use the same arguments you would give | |
326 | @code{grep} when running it normally: a @code{grep}-style regexp | |
327 | (usually in single-quotes to quote the shell's special characters) | |
328 | followed by file names, which may use wildcards. If you specify a | |
329 | prefix argument for @kbd{M-x grep}, it figures out the tag | |
330 | (@pxref{Tags}) around point, and puts that into the default | |
331 | @code{grep} command. | |
332 | ||
333 | The output from @code{grep} goes in the @samp{*grep*} buffer. You | |
334 | can find the corresponding lines in the original files using @kbd{C-x | |
335 | `}, @key{RET}, and so forth, just like compilation errors. | |
336 | ||
337 | Some grep programs accept a @samp{--color} option to output special | |
338 | markers around matches for the purpose of highlighting. You can make | |
339 | use of this feature by setting @code{grep-highlight-matches} to t. | |
340 | When displaying a match in the source buffer, the exact match will be | |
341 | highlighted, instead of the entire source line. | |
342 | ||
343 | @findex grep-find | |
344 | @findex find-grep | |
345 | The command @kbd{M-x grep-find} (also available as @kbd{M-x | |
346 | find-grep}) is similar to @kbd{M-x grep}, but it supplies a different | |
347 | initial default for the command---one that runs both @code{find} and | |
348 | @code{grep}, so as to search every file in a directory tree. See also | |
349 | the @code{find-grep-dired} command, in @ref{Dired and Find}. | |
350 | ||
ff994d96 RS |
351 | @node Flymake |
352 | @section Finding Syntax Errors On The Fly | |
353 | @cindex checking syntax | |
354 | ||
355 | Flymake mode is a minor mode that performs on-the-fly syntax | |
356 | checking for many programming and markup languages, including C, C++, | |
357 | Perl, HTML, and @TeX{}/La@TeX{}. It is somewhat analogous to Flyspell | |
358 | mode, which performs spell checking for ordinary human languages in a | |
359 | similar fashion (@pxref{Spelling}). As you edit a file, Flymake mode | |
360 | runs an appropriate syntax checking tool in the background, using a | |
361 | temporary copy of the buffer. It then parses the error and warning | |
362 | messages, and highlights the erroneous lines in the buffer. The | |
363 | syntax checking tool used depends on the language; for example, for | |
364 | C/C++ files this is usually the C compiler. Flymake can also use | |
365 | build tools such as @code{make} for checking complicated projects. | |
366 | ||
367 | To activate Flymake mode, type @kbd{M-x flymake-mode}. You can move | |
368 | to the errors spotted by Flymake mode with @kbd{M-x | |
369 | flymake-goto-next-error} and @kbd{M-x flymake-goto-prev-error}. To | |
370 | display any error messages associated with the current line, use | |
371 | @kbd{M-x flymake-display-err-menu-for-current-line}. | |
372 | ||
373 | For more details about using Flymake, see @ref{Top, Flymake, | |
374 | Flymake, flymake, The Flymake Manual}. | |
375 | ||
6bf7aab6 DL |
376 | @node Debuggers |
377 | @section Running Debuggers Under Emacs | |
378 | @cindex debuggers | |
379 | @cindex GUD library | |
380 | @cindex GDB | |
381 | @cindex DBX | |
382 | @cindex SDB | |
383 | @cindex XDB | |
384 | @cindex Perldb | |
ed4389af | 385 | @cindex bashdb |
6bf7aab6 DL |
386 | @cindex JDB |
387 | @cindex PDB | |
388 | ||
389 | @c Do you believe in GUD? | |
390 | The GUD (Grand Unified Debugger) library provides an interface to | |
31b4c1b7 NR |
391 | various symbolic debuggers from within Emacs. We recommend the |
392 | debugger GDB, which is free software, but you can also run DBX, SDB or | |
393 | XDB if you have them. GUD can also serve as an interface to Perl's | |
394 | debugging mode, the Python debugger PDB, the bash debugger, and to | |
395 | JDB, the Java Debugger. @xref{Debugging,, The Lisp Debugger, elisp, | |
396 | the Emacs Lisp Reference Manual}, for information on debugging Emacs | |
397 | Lisp programs. | |
6bf7aab6 DL |
398 | |
399 | @menu | |
400 | * Starting GUD:: How to start a debugger subprocess. | |
401 | * Debugger Operation:: Connection between the debugger and source buffers. | |
402 | * Commands of GUD:: Key bindings for common commands. | |
403 | * GUD Customization:: Defining your own commands for GUD. | |
f9ad161b RS |
404 | * GDB Graphical Interface:: An enhanced mode that uses GDB features to |
405 | implement a graphical debugging environment through | |
406 | Emacs. | |
6bf7aab6 DL |
407 | @end menu |
408 | ||
409 | @node Starting GUD | |
410 | @subsection Starting GUD | |
411 | ||
412 | There are several commands for starting a debugger, each corresponding | |
413 | to a particular debugger program. | |
414 | ||
415 | @table @kbd | |
416 | @item M-x gdb @key{RET} @var{file} @key{RET} | |
417 | @findex gdb | |
499de9ba RS |
418 | Run GDB as a subprocess of Emacs. By default, this operates in |
419 | graphical mode; @xref{GDB Graphical Interface}. Graphical mode | |
420 | does not support any other debuggers. | |
f9ad161b | 421 | |
6bf7aab6 DL |
422 | @item M-x dbx @key{RET} @var{file} @key{RET} |
423 | @findex dbx | |
4125ceb0 | 424 | Similar, but run DBX instead of GDB. |
6bf7aab6 DL |
425 | |
426 | @item M-x xdb @key{RET} @var{file} @key{RET} | |
427 | @findex xdb | |
428 | @vindex gud-xdb-directories | |
4125ceb0 | 429 | Similar, but run XDB instead of GDB. Use the variable |
6bf7aab6 DL |
430 | @code{gud-xdb-directories} to specify directories to search for source |
431 | files. | |
432 | ||
433 | @item M-x sdb @key{RET} @var{file} @key{RET} | |
434 | @findex sdb | |
4125ceb0 | 435 | Similar, but run SDB instead of GDB. |
6bf7aab6 DL |
436 | |
437 | Some versions of SDB do not mention source file names in their | |
438 | messages. When you use them, you need to have a valid tags table | |
439 | (@pxref{Tags}) in order for GUD to find functions in the source code. | |
440 | If you have not visited a tags table or the tags table doesn't list one | |
441 | of the functions, you get a message saying @samp{The sdb support | |
442 | requires a valid tags table to work}. If this happens, generate a valid | |
443 | tags table in the working directory and try again. | |
444 | ||
ed4389af RS |
445 | @item M-x bashdb @key{RET} @var{file} @key{RET} |
446 | @findex bashdb | |
447 | Run the bash debugger to debug @var{file}, a shell script. | |
448 | ||
6bf7aab6 DL |
449 | @item M-x perldb @key{RET} @var{file} @key{RET} |
450 | @findex perldb | |
451 | Run the Perl interpreter in debug mode to debug @var{file}, a Perl program. | |
452 | ||
453 | @item M-x jdb @key{RET} @var{file} @key{RET} | |
454 | @findex jdb | |
455 | Run the Java debugger to debug @var{file}. | |
456 | ||
457 | @item M-x pdb @key{RET} @var{file} @key{RET} | |
458 | @findex pdb | |
459 | Run the Python debugger to debug @var{file}. | |
460 | @end table | |
461 | ||
462 | Each of these commands takes one argument: a command line to invoke | |
463 | the debugger. In the simplest case, specify just the name of the | |
464 | executable file you want to debug. You may also use options that the | |
465 | debugger supports. However, shell wildcards and variables are not | |
466 | allowed. GUD assumes that the first argument not starting with a | |
467 | @samp{-} is the executable file name. | |
468 | ||
6bf7aab6 DL |
469 | @node Debugger Operation |
470 | @subsection Debugger Operation | |
471 | ||
3605e23f | 472 | @cindex fringes, and current execution line in GUD |
6bf7aab6 DL |
473 | When you run a debugger with GUD, the debugger uses an Emacs buffer |
474 | for its ordinary input and output. This is called the GUD buffer. The | |
475 | debugger displays the source files of the program by visiting them in | |
476 | Emacs buffers. An arrow (@samp{=>}) in one of these buffers indicates | |
8643647c RS |
477 | the current execution line.@footnote{Under a window system, the arrow |
478 | appears in the left fringe of the Emacs window.} Moving point in this | |
479 | buffer does not move the arrow. | |
6bf7aab6 DL |
480 | |
481 | You can start editing these source files at any time in the buffers | |
58fa012d | 482 | that display them. The arrow is not part of the file's |
6bf7aab6 DL |
483 | text; it appears only on the screen. If you do modify a source file, |
484 | keep in mind that inserting or deleting lines will throw off the arrow's | |
485 | positioning; GUD has no way of figuring out which line corresponded | |
486 | before your changes to the line number in a debugger message. Also, | |
487 | you'll typically have to recompile and restart the program for your | |
488 | changes to be reflected in the debugger's tables. | |
489 | ||
490 | If you wish, you can control your debugger process entirely through the | |
491 | debugger buffer, which uses a variant of Shell mode. All the usual | |
492 | commands for your debugger are available, and you can use the Shell mode | |
493 | history commands to repeat them. @xref{Shell Mode}. | |
494 | ||
499de9ba RS |
495 | @cindex tooltips with GUD |
496 | @vindex tooltip-gud-modes | |
c2332b4f NR |
497 | @vindex gud-tooltip-mode |
498 | @vindex gud-tooltip-echo-area | |
499de9ba | 499 | The Tooltip facility (@pxref{Tooltips}) provides support for GUD@. |
8a25d51a NR |
500 | You activate this feature by turning on the minor mode |
501 | @code{gud-tooltip-mode}. Then you can display a variable's value in a | |
502 | tooltip simply by pointing at it with the mouse. In graphical mode, | |
503 | with a C program, you can also display the @code{#define} directive | |
504 | associated with an identifier when the program is not executing. This | |
505 | operates in the GUD buffer and in source buffers with major modes in | |
c2332b4f NR |
506 | the list @code{gud-tooltip-modes}. If the variable |
507 | @code{gud-tooltip-echo-area} is non-@code{nil} then the help text is | |
508 | displayed in the echo area. | |
499de9ba | 509 | |
6bf7aab6 DL |
510 | @node Commands of GUD |
511 | @subsection Commands of GUD | |
512 | ||
513 | The GUD interaction buffer uses a variant of Shell mode, so the | |
514 | commands of Shell mode are available (@pxref{Shell Mode}). GUD mode | |
515 | also provides commands for setting and clearing breakpoints, for | |
516 | selecting stack frames, and for stepping through the program. These | |
517 | commands are available both in the GUD buffer and globally, but with | |
8d66c08b NR |
518 | different key bindings. It also has its own toolbar from which you |
519 | can invoke the more common commands by clicking on the appropriate | |
520 | icon. This is particularly useful for repetitive commands like | |
521 | gud-next and gud-step and allows the user to hide the GUD buffer. | |
6bf7aab6 | 522 | |
58fa012d EZ |
523 | The breakpoint commands are normally used in source file buffers, |
524 | because that is the easiest way to specify where to set or clear the | |
525 | breakpoint. Here's the global command to set a breakpoint: | |
6bf7aab6 DL |
526 | |
527 | @table @kbd | |
528 | @item C-x @key{SPC} | |
529 | @kindex C-x SPC | |
530 | Set a breakpoint on the source line that point is on. | |
531 | @end table | |
532 | ||
533 | @kindex C-x C-a @r{(GUD)} | |
534 | Here are the other special commands provided by GUD. The keys | |
535 | starting with @kbd{C-c} are available only in the GUD interaction | |
536 | buffer. The key bindings that start with @kbd{C-x C-a} are available in | |
537 | the GUD interaction buffer and also in source files. | |
538 | ||
539 | @table @kbd | |
540 | @item C-c C-l | |
541 | @kindex C-c C-l @r{(GUD)} | |
542 | @itemx C-x C-a C-l | |
543 | @findex gud-refresh | |
544 | Display in another window the last line referred to in the GUD | |
545 | buffer (that is, the line indicated in the last location message). | |
546 | This runs the command @code{gud-refresh}. | |
547 | ||
548 | @item C-c C-s | |
549 | @kindex C-c C-s @r{(GUD)} | |
550 | @itemx C-x C-a C-s | |
551 | @findex gud-step | |
552 | Execute a single line of code (@code{gud-step}). If the line contains | |
553 | a function call, execution stops after entering the called function. | |
554 | ||
555 | @item C-c C-n | |
556 | @kindex C-c C-n @r{(GUD)} | |
557 | @itemx C-x C-a C-n | |
558 | @findex gud-next | |
559 | Execute a single line of code, stepping across entire function calls | |
560 | at full speed (@code{gud-next}). | |
561 | ||
562 | @item C-c C-i | |
563 | @kindex C-c C-i @r{(GUD)} | |
564 | @itemx C-x C-a C-i | |
565 | @findex gud-stepi | |
566 | Execute a single machine instruction (@code{gud-stepi}). | |
567 | ||
568 | @need 3000 | |
569 | @item C-c C-r | |
570 | @kindex C-c C-r @r{(GUD)} | |
571 | @itemx C-x C-a C-r | |
572 | @findex gud-cont | |
573 | Continue execution without specifying any stopping point. The program | |
574 | will run until it hits a breakpoint, terminates, or gets a signal that | |
575 | the debugger is checking for (@code{gud-cont}). | |
576 | ||
577 | @need 1000 | |
578 | @item C-c C-d | |
579 | @kindex C-c C-d @r{(GUD)} | |
580 | @itemx C-x C-a C-d | |
581 | @findex gud-remove | |
582 | Delete the breakpoint(s) on the current source line, if any | |
583 | (@code{gud-remove}). If you use this command in the GUD interaction | |
584 | buffer, it applies to the line where the program last stopped. | |
585 | ||
586 | @item C-c C-t | |
587 | @kindex C-c C-t @r{(GUD)} | |
588 | @itemx C-x C-a C-t | |
589 | @findex gud-tbreak | |
590 | Set a temporary breakpoint on the current source line, if any. | |
591 | If you use this command in the GUD interaction buffer, | |
592 | it applies to the line where the program last stopped. | |
593 | @end table | |
594 | ||
595 | The above commands are common to all supported debuggers. If you are | |
596 | using GDB or (some versions of) DBX, these additional commands are available: | |
597 | ||
598 | @table @kbd | |
599 | @item C-c < | |
600 | @kindex C-c < @r{(GUD)} | |
601 | @itemx C-x C-a < | |
602 | @findex gud-up | |
603 | Select the next enclosing stack frame (@code{gud-up}). This is | |
604 | equivalent to the @samp{up} command. | |
605 | ||
606 | @item C-c > | |
607 | @kindex C-c > @r{(GUD)} | |
608 | @itemx C-x C-a > | |
609 | @findex gud-down | |
610 | Select the next inner stack frame (@code{gud-down}). This is | |
611 | equivalent to the @samp{down} command. | |
612 | @end table | |
613 | ||
614 | If you are using GDB, these additional key bindings are available: | |
615 | ||
616 | @table @kbd | |
f9ad161b RS |
617 | @item C-c C-r |
618 | @kindex C-c C-r @r{(GUD)} | |
619 | @itemx C-x C-a C-r | |
620 | @findex gud-run | |
621 | Start execution of the program (@code{gud-run}). | |
622 | ||
623 | @item C-c C-u | |
624 | @kindex C-c C-u @r{(GUD)} | |
625 | @itemx C-x C-a C-u | |
626 | @findex gud-until | |
627 | Continue execution to the current line. The program will run until | |
628 | it hits a breakpoint, terminates, gets a signal that the debugger is | |
629 | checking for, or reaches the line on which the cursor currently sits | |
630 | (@code{gud-until}). | |
631 | ||
6bf7aab6 DL |
632 | @item @key{TAB} |
633 | @kindex TAB @r{(GUD)} | |
634 | @findex gud-gdb-complete-command | |
635 | With GDB, complete a symbol name (@code{gud-gdb-complete-command}). | |
636 | This key is available only in the GUD interaction buffer, and requires | |
637 | GDB versions 4.13 and later. | |
638 | ||
639 | @item C-c C-f | |
640 | @kindex C-c C-f @r{(GUD)} | |
641 | @itemx C-x C-a C-f | |
642 | @findex gud-finish | |
643 | Run the program until the selected stack frame returns (or until it | |
644 | stops for some other reason). | |
5b7fc395 | 645 | |
44fa0ae8 RS |
646 | @item C-x C-a C-j |
647 | @kindex C-x C-a C-j @r{(GUD)} | |
5b7fc395 | 648 | @findex gud-jump |
44fa0ae8 RS |
649 | Only useful in a source buffer, (@code{gud-jump}) transfers the |
650 | program's execution point to the current line. In other words, the | |
651 | next line that the program executes will be the one where you gave the | |
652 | command. If the new execution line is in a different function from | |
653 | the previously one, GDB prompts for confirmation since the results may | |
654 | be bizarre. See the GDB manual entry regarding @code{jump} for | |
655 | details. | |
6bf7aab6 DL |
656 | @end table |
657 | ||
658 | These commands interpret a numeric argument as a repeat count, when | |
659 | that makes sense. | |
660 | ||
661 | Because @key{TAB} serves as a completion command, you can't use it to | |
662 | enter a tab as input to the program you are debugging with GDB. | |
663 | Instead, type @kbd{C-q @key{TAB}} to enter a tab. | |
664 | ||
665 | @node GUD Customization | |
666 | @subsection GUD Customization | |
667 | ||
668 | @vindex gdb-mode-hook | |
669 | @vindex dbx-mode-hook | |
670 | @vindex sdb-mode-hook | |
671 | @vindex xdb-mode-hook | |
672 | @vindex perldb-mode-hook | |
673 | @vindex pdb-mode-hook | |
674 | @vindex jdb-mode-hook | |
675 | On startup, GUD runs one of the following hooks: @code{gdb-mode-hook}, | |
676 | if you are using GDB; @code{dbx-mode-hook}, if you are using DBX; | |
677 | @code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you | |
678 | are using XDB; @code{perldb-mode-hook}, for Perl debugging mode; | |
74b1aac1 | 679 | @code{pdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB. You can |
6bf7aab6 DL |
680 | use these hooks to define custom key bindings for the debugger |
681 | interaction buffer. @xref{Hooks}. | |
682 | ||
683 | Here is a convenient way to define a command that sends a particular | |
684 | command string to the debugger, and set up a key binding for it in the | |
685 | debugger interaction buffer: | |
686 | ||
687 | @findex gud-def | |
688 | @example | |
689 | (gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring}) | |
690 | @end example | |
691 | ||
692 | This defines a command named @var{function} which sends | |
693 | @var{cmdstring} to the debugger process, and gives it the documentation | |
7fb4961c | 694 | string @var{docstring}. You can then use the command @var{function} in any |
6bf7aab6 DL |
695 | buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds |
696 | the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to | |
697 | @kbd{C-x C-a @var{binding}} generally. | |
698 | ||
699 | The command string @var{cmdstring} may contain certain | |
700 | @samp{%}-sequences that stand for data to be filled in at the time | |
701 | @var{function} is called: | |
702 | ||
703 | @table @samp | |
704 | @item %f | |
705 | The name of the current source file. If the current buffer is the GUD | |
706 | buffer, then the ``current source file'' is the file that the program | |
707 | stopped in. | |
708 | @c This said, ``the name of the file the program counter was in at the last breakpoint.'' | |
709 | @c But I suspect it is really the last stop file. | |
710 | ||
711 | @item %l | |
712 | The number of the current source line. If the current buffer is the GUD | |
713 | buffer, then the ``current source line'' is the line that the program | |
714 | stopped in. | |
715 | ||
716 | @item %e | |
717 | The text of the C lvalue or function-call expression at or adjacent to point. | |
718 | ||
719 | @item %a | |
720 | The text of the hexadecimal address at or adjacent to point. | |
721 | ||
722 | @item %p | |
723 | The numeric argument of the called function, as a decimal number. If | |
724 | the command is used without a numeric argument, @samp{%p} stands for the | |
725 | empty string. | |
726 | ||
727 | If you don't use @samp{%p} in the command string, the command you define | |
728 | ignores any numeric argument. | |
729 | @end table | |
730 | ||
f9ad161b RS |
731 | @node GDB Graphical Interface |
732 | @subsection GDB Graphical Interface | |
733 | ||
499de9ba | 734 | By default, the command @code{gdb} starts GDB using a graphical |
31b4c1b7 NR |
735 | interface where you view and control the program's data using Emacs |
736 | windows. You can still interact with GDB through the GUD buffer, but | |
737 | the point of this mode is that you can do it through menus and clicks, | |
0ace9c9e NR |
738 | without needing to know GDB commands. For example, you can click |
739 | @kbd{Mouse-1} on a line of the source buffer, in the fringe or display | |
740 | margin, to set a breakpoint there. If a breakpoint already exists on | |
741 | that line, this action will remove it | |
742 | (@code{gdb-mouse-set-clear-breakpoint}). Where Emacs uses the margin | |
743 | to display breakpoints, it is also possible to enable or disable them | |
744 | when you click @kbd{Mouse-3} there | |
745 | (@code{gdb-mouse-toggle--breakpoint}). | |
31b4c1b7 | 746 | |
499de9ba | 747 | @vindex gud-gdb-command-name |
f9ad161b | 748 | @findex gdba |
499de9ba RS |
749 | You can also run GDB in text command mode, which creates a buffer |
750 | for input and output to GDB. To do this, set | |
751 | @code{gud-gdb-command-name} to @code{"gdb --fullname"} or edit the | |
752 | startup command in the minibuffer to say that. You need to do use | |
753 | text command mode to run multiple debugging sessions within one Emacs | |
754 | session. If you have customised @code{gud-gdb-command-name} in that | |
755 | way, then you can use @kbd{M-x gdba} to invoke GDB in graphical mode. | |
f9ad161b RS |
756 | |
757 | @menu | |
96110242 | 758 | * Layout:: Control the number of displayed buffers. |
f9ad161b | 759 | * Breakpoints Buffer:: A breakpoint control panel. |
254196f5 | 760 | * Stack Buffer:: Select a frame from the call stack. |
8d66c08b | 761 | * Watch Expressions:: Monitor variable values in the speedbar. |
31b4c1b7 NR |
762 | * Other Buffers:: Input/output, locals, registers, assembler, threads |
763 | and memory buffers. | |
f9ad161b RS |
764 | @end menu |
765 | ||
96110242 NR |
766 | @node Layout |
767 | @subsubsection Layout | |
768 | @cindex GDB User Interface layout | |
769 | ||
770 | @findex gdb-many-windows | |
771 | @vindex gdb-many-windows | |
772 | ||
773 | If the variable @code{gdb-many-windows} is @code{nil} (the default | |
774 | value) then gdb just pops up the GUD buffer unless the variable | |
775 | @code{gdb-show-main} is non-@code{nil}. In this case it starts with | |
776 | two windows: one displaying the GUD buffer and the other with the | |
777 | source file with the main routine of the inferior. | |
778 | ||
779 | If @code{gdb-many-windows} is non-@code{nil}, regardless of the value of | |
780 | @code{gdb-show-main}, the layout below will appear unless | |
781 | @code{gdb-use-inferior-io-buffer} is @code{nil}. In this case the | |
782 | source buffer occupies the full width of the frame. | |
783 | ||
784 | @multitable @columnfractions .5 .5 | |
785 | @item GUD buffer (I/O of GDB) | |
786 | @tab Locals buffer | |
787 | @item | |
788 | @tab | |
789 | @item Source buffer | |
790 | @tab Input/Output (of inferior) buffer | |
791 | @item | |
792 | @tab | |
793 | @item Stack buffer | |
794 | @tab Breakpoints buffer | |
795 | @end multitable | |
796 | ||
797 | To toggle this layout, do @kbd{M-x gdb-many-windows}. | |
798 | ||
799 | @findex gdb-restore-windows | |
800 | If you change the window layout, for example, while editing and | |
801 | re-compiling your program, then you can restore it with the command | |
802 | @code{gdb-restore-windows}. | |
803 | ||
804 | You may also choose which additional buffers you want to display, | |
805 | either in the same frame or a different one. Select GDB-windows or | |
806 | GDB-Frames from the menu-bar under the heading GUD. If the menu-bar | |
807 | is unavailable, type @code{M-x | |
808 | gdb-display-@var{buffertype}-buffer} or @code{M-x | |
809 | gdb-frame-@var{buffertype}-buffer} respectively, where @var{buffertype} | |
810 | is the relevant buffer type e.g breakpoints. | |
811 | ||
31b4c1b7 NR |
812 | When you finish debugging then kill the GUD buffer with @kbd{C-x k}, |
813 | which will also kill all the buffers associated with the session. | |
814 | However you need not do this if, after editing and re-compiling your | |
815 | source code within Emacs, you wish continue debugging. When you | |
816 | restart execution, GDB will automatically find your new executable. | |
817 | Keeping the GUD buffer has the advantage of keeping the shell history | |
818 | as well as GDB's breakpoints. You need to check, however, that the | |
819 | breakpoints in the recently edited code are still where you want them. | |
820 | ||
f9ad161b RS |
821 | @node Breakpoints Buffer |
822 | @subsubsection Breakpoints Buffer | |
823 | ||
254196f5 | 824 | The breakpoints buffer shows the existing breakpoints and watchpoints |
f9ad161b RS |
825 | (@pxref{Breakpoints,,, gdb, The GNU debugger}). It has three special |
826 | commands: | |
827 | ||
828 | @table @kbd | |
254196f5 | 829 | @item @key{SPC} |
f9ad161b RS |
830 | @kindex SPC @r{(GDB breakpoints buffer)} |
831 | @findex gdb-toggle-breakpoint | |
832 | Enable/disable the breakpoint at the current line | |
833 | (@code{gdb-toggle-breakpoint}). On a graphical display, this changes | |
834 | the color of a bullet in the margin of the source buffer at the | |
835 | relevant line. This is red when the breakpoint is enabled and grey | |
836 | when it is disabled. Text-only terminals correspondingly display | |
837 | a @samp{B} or @samp{b}. | |
838 | ||
839 | @item @kbd{d} | |
840 | @kindex d @r{(GDB breakpoints buffer)} | |
841 | @findex gdb-delete-breakpoint | |
842 | Delete the breakpoint at the current line (@code{gdb-delete-breakpoint}). | |
843 | ||
844 | @item @key{RET} | |
845 | @kindex RET @r{(GDB breakpoints buffer)} | |
846 | @findex gdb-goto-breakpoint | |
847 | Display the file in the source buffer at the breakpoint specified at | |
90563cb3 NR |
848 | the current line (@code{gdb-goto-breakpoint}). Alternatively, click |
849 | @kbd{Mouse-2} on the breakpoint that you wish to visit. | |
f9ad161b RS |
850 | @end table |
851 | ||
852 | @node Stack Buffer | |
853 | @subsubsection Stack Buffer | |
854 | ||
855 | The stack buffer displays a @dfn{call stack}, with one line for each | |
856 | of the nested subroutine calls (@dfn{stack frames}) now active in the | |
857 | program. @xref{Backtrace,,info stack, gdb, The GNU debugger}. | |
858 | ||
90563cb3 NR |
859 | The selected frame is displayed in reverse contrast. Move point to |
860 | any frame in the stack and type @key{RET} to select it (@code{gdb-frames-select}) | |
861 | and display the associated source in the source buffer. Alternatively, | |
862 | click @kbd{Mouse-2} to make the selected frame become the current one. | |
863 | If the locals buffer is displayed then its contents update to display | |
864 | the variables that are local to the new frame. | |
f9ad161b | 865 | |
9b418429 NR |
866 | @node Watch Expressions |
867 | @subsubsection Watch Expressions | |
868 | @cindex Watching expressions in GDB | |
f9ad161b RS |
869 | |
870 | If you want to see how a variable changes each time your program stops | |
9b418429 NR |
871 | then place the cursor over the variable name and click on the watch |
872 | icon in the toolbar (@code{gud-watch}). | |
f9ad161b | 873 | |
8d66c08b NR |
874 | Each watch expression is displayed in the speedbar. Complex data |
875 | types, such as arrays, structures and unions are represented in a tree | |
876 | format. To expand or contract a complex data type, click @kbd{Mouse-2} | |
877 | on the tag to the left of the expression. | |
f9ad161b | 878 | |
9b418429 NR |
879 | @kindex RET @r{(GDB speedbar)} |
880 | @findex gdb-var-delete | |
8d66c08b | 881 | With the cursor over the root expression of a complex data type, type |
96110242 | 882 | @kbd{D} to delete it from the speedbar |
8d66c08b NR |
883 | (@code{gdb-var-delete}). |
884 | ||
885 | @findex gdb-edit-value | |
886 | With the cursor over a simple data type or an element of a complex | |
887 | data type which holds a value, type @key{RET} or click @kbd{Mouse-2} to edit | |
888 | its value. A prompt for a new value appears in the mini-buffer | |
889 | (@code{gdb-edit-value}). | |
890 | ||
a1a3a37a NR |
891 | If you set the variable @code{gdb-show-changed-values} to |
892 | non-@code{nil} (the default value), then Emacs will use | |
893 | font-lock-warning-face to display values that have recently changed in | |
894 | the speedbar. | |
8d66c08b NR |
895 | |
896 | If you set the variable @code{gdb-use-colon-colon-notation} to a | |
897 | non-@code{nil} value, then, in C, Emacs will use the | |
898 | FUNCTION::VARIABLE format to display variables in the speedbar. | |
a1a3a37a NR |
899 | Since this does not work for variables defined in compound statements, |
900 | the default value is @code{nil}. | |
f9ad161b RS |
901 | |
902 | @node Other Buffers | |
903 | @subsubsection Other Buffers | |
904 | ||
905 | @table @asis | |
906 | @item Input/Output Buffer | |
96110242 NR |
907 | If the variable @code{gdb-use-inferior-io-buffer} is non-@code{nil}, |
908 | the executable program that is being debugged takes its input and | |
f9ad161b RS |
909 | displays its output here. Some of the commands from shell mode are |
910 | available here. @xref{Shell Mode}. | |
911 | ||
912 | @item Locals Buffer | |
913 | The locals buffer displays the values of local variables of the | |
914 | current frame for simple data types (@pxref{Frame Info,,, gdb, The GNU | |
915 | debugger}). | |
916 | ||
917 | Arrays and structures display their type only. You must display them | |
500509e2 | 918 | separately to examine their values. @xref{Watch Expressions}. |
f9ad161b RS |
919 | |
920 | @item Registers Buffer | |
921 | The registers buffer displays the values held by the registers | |
922 | (@pxref{Registers,,, gdb, The GNU debugger}). | |
923 | ||
924 | @item Assembler Buffer | |
925 | The assembler buffer displays the current frame as machine code. An | |
926 | overlay arrow points to the current instruction and you can set and | |
31b4c1b7 NR |
927 | remove breakpoints as with the source buffer. Breakpoint icons also |
928 | appear in the fringe or margin. | |
8d66c08b NR |
929 | |
930 | @item Threads Buffer | |
931 | ||
932 | The threads buffer displays a summary of all threads currently in your | |
31b4c1b7 | 933 | program (@pxref{Threads,,, gdb, The GNU debugger}). Move point to |
8d66c08b NR |
934 | any thread in the list and type @key{RET} to make it become the |
935 | current thread (@code{gdb-threads-select}) and display the associated | |
936 | source in the source buffer. Alternatively, click @kbd{Mouse-2} to | |
937 | make the selected thread become the current one. | |
938 | ||
31b4c1b7 NR |
939 | @item Memory Buffer |
940 | ||
941 | The memory buffer allows the user to examine sections of program | |
942 | memory (@pxref{Memory,,, gdb, The GNU debugger}). Click @kbd{Mouse-1} | |
943 | on the appropriate part of the header line to change the starting | |
944 | address or number of data items that the buffer displays. | |
945 | Click @kbd{Mouse-3} on the header line to select the display format | |
946 | or unit size for these data items. | |
947 | ||
f9ad161b RS |
948 | @end table |
949 | ||
6bf7aab6 DL |
950 | @node Executing Lisp |
951 | @section Executing Lisp Expressions | |
952 | ||
953 | Emacs has several different major modes for Lisp and Scheme. They are | |
954 | the same in terms of editing commands, but differ in the commands for | |
955 | executing Lisp expressions. Each mode has its own purpose. | |
956 | ||
957 | @table @asis | |
958 | @item Emacs-Lisp mode | |
959 | The mode for editing source files of programs to run in Emacs Lisp. | |
960 | This mode defines @kbd{C-M-x} to evaluate the current defun. | |
961 | @xref{Lisp Libraries}. | |
962 | @item Lisp Interaction mode | |
963 | The mode for an interactive session with Emacs Lisp. It defines | |
964 | @kbd{C-j} to evaluate the sexp before point and insert its value in the | |
965 | buffer. @xref{Lisp Interaction}. | |
966 | @item Lisp mode | |
967 | The mode for editing source files of programs that run in Lisps other | |
968 | than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun | |
969 | to an inferior Lisp process. @xref{External Lisp}. | |
970 | @item Inferior Lisp mode | |
971 | The mode for an interactive session with an inferior Lisp process. | |
972 | This mode combines the special features of Lisp mode and Shell mode | |
973 | (@pxref{Shell Mode}). | |
974 | @item Scheme mode | |
975 | Like Lisp mode but for Scheme programs. | |
976 | @item Inferior Scheme mode | |
977 | The mode for an interactive session with an inferior Scheme process. | |
978 | @end table | |
979 | ||
980 | Most editing commands for working with Lisp programs are in fact | |
981 | available globally. @xref{Programs}. | |
982 | ||
983 | @node Lisp Libraries | |
984 | @section Libraries of Lisp Code for Emacs | |
985 | @cindex libraries | |
986 | @cindex loading Lisp code | |
987 | ||
988 | Lisp code for Emacs editing commands is stored in files whose names | |
989 | conventionally end in @file{.el}. This ending tells Emacs to edit them in | |
990 | Emacs-Lisp mode (@pxref{Executing Lisp}). | |
991 | ||
992 | @findex load-file | |
993 | To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This | |
994 | command reads a file name using the minibuffer and then executes the | |
995 | contents of that file as Lisp code. It is not necessary to visit the | |
996 | file first; in any case, this command reads the file as found on disk, | |
997 | not text in an Emacs buffer. | |
998 | ||
999 | @findex load | |
1000 | @findex load-library | |
1001 | Once a file of Lisp code is installed in the Emacs Lisp library | |
1002 | directories, users can load it using @kbd{M-x load-library}. Programs can | |
1003 | load it by calling @code{load-library}, or with @code{load}, a more primitive | |
1004 | function that is similar but accepts some additional arguments. | |
1005 | ||
1006 | @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it | |
1007 | searches a sequence of directories and tries three file names in each | |
1008 | directory. Suppose your argument is @var{lib}; the three names are | |
1009 | @file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just | |
1010 | @file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention | |
1011 | the result of compiling @file{@var{lib}.el}; it is better to load the | |
1012 | compiled file, since it will load and run faster. | |
1013 | ||
1014 | If @code{load-library} finds that @file{@var{lib}.el} is newer than | |
48dbca2c | 1015 | @file{@var{lib}.elc} file, it issues a warning, because it's likely that |
6bf7aab6 DL |
1016 | somebody made changes to the @file{.el} file and forgot to recompile |
1017 | it. | |
1018 | ||
1019 | Because the argument to @code{load-library} is usually not in itself | |
1020 | a valid file name, file name completion is not available. Indeed, when | |
1021 | using this command, you usually do not know exactly what file name | |
1022 | will be used. | |
1023 | ||
1024 | @vindex load-path | |
1025 | The sequence of directories searched by @kbd{M-x load-library} is | |
1026 | specified by the variable @code{load-path}, a list of strings that are | |
1027 | directory names. The default value of the list contains the directory where | |
1028 | the Lisp code for Emacs itself is stored. If you have libraries of | |
1029 | your own, put them in a single directory and add that directory | |
1030 | to @code{load-path}. @code{nil} in this list stands for the current default | |
1031 | directory, but it is probably not a good idea to put @code{nil} in the | |
1032 | list. If you find yourself wishing that @code{nil} were in the list, | |
1033 | most likely what you really want to do is use @kbd{M-x load-file} | |
1034 | this once. | |
1035 | ||
1036 | @cindex autoload | |
1037 | Often you do not have to give any command to load a library, because | |
1038 | the commands defined in the library are set up to @dfn{autoload} that | |
1039 | library. Trying to run any of those commands calls @code{load} to load | |
1040 | the library; this replaces the autoload definitions with the real ones | |
1041 | from the library. | |
1042 | ||
1043 | @cindex byte code | |
1044 | Emacs Lisp code can be compiled into byte-code which loads faster, | |
1045 | takes up less space when loaded, and executes faster. @xref{Byte | |
1046 | Compilation,, Byte Compilation, elisp, the Emacs Lisp Reference Manual}. | |
1047 | By convention, the compiled code for a library goes in a separate file | |
1048 | whose name consists of the library source file with @samp{c} appended. | |
1049 | Thus, the compiled code for @file{foo.el} goes in @file{foo.elc}. | |
1050 | That's why @code{load-library} searches for @samp{.elc} files first. | |
1051 | ||
493c59e0 EZ |
1052 | @vindex load-dangerous-libraries |
1053 | @cindex Lisp files byte-compiled by XEmacs | |
a50c7a80 RS |
1054 | By default, Emacs refuses to load compiled Lisp files which were |
1055 | compiled with XEmacs, a modified versions of Emacs---they can cause | |
1056 | Emacs to crash. Set the variable @code{load-dangerous-libraries} to | |
1057 | @code{t} if you want to try loading them. | |
493c59e0 | 1058 | |
6bf7aab6 | 1059 | @node Lisp Eval |
dd525369 | 1060 | @section Evaluating Emacs Lisp Expressions |
6bf7aab6 DL |
1061 | @cindex Emacs-Lisp mode |
1062 | @cindex mode, Emacs-Lisp | |
1063 | ||
1064 | @findex emacs-lisp-mode | |
1065 | Lisp programs intended to be run in Emacs should be edited in | |
1066 | Emacs-Lisp mode; this happens automatically for file names ending in | |
1067 | @file{.el}. By contrast, Lisp mode itself is used for editing Lisp | |
1068 | programs intended for other Lisp systems. To switch to Emacs-Lisp mode | |
1069 | explicitly, use the command @kbd{M-x emacs-lisp-mode}. | |
1070 | ||
1071 | For testing of Lisp programs to run in Emacs, it is often useful to | |
1072 | evaluate part of the program as it is found in the Emacs buffer. For | |
1073 | example, after changing the text of a Lisp function definition, | |
1074 | evaluating the definition installs the change for future calls to the | |
1075 | function. Evaluation of Lisp expressions is also useful in any kind of | |
1076 | editing, for invoking noninteractive functions (functions that are | |
1077 | not commands). | |
1078 | ||
1079 | @table @kbd | |
1080 | @item M-: | |
1081 | Read a single Lisp expression in the minibuffer, evaluate it, and print | |
1082 | the value in the echo area (@code{eval-expression}). | |
1083 | @item C-x C-e | |
1084 | Evaluate the Lisp expression before point, and print the value in the | |
1085 | echo area (@code{eval-last-sexp}). | |
1086 | @item C-M-x | |
1087 | Evaluate the defun containing or after point, and print the value in | |
1088 | the echo area (@code{eval-defun}). | |
1089 | @item M-x eval-region | |
1090 | Evaluate all the Lisp expressions in the region. | |
1091 | @item M-x eval-current-buffer | |
1092 | Evaluate all the Lisp expressions in the buffer. | |
1093 | @end table | |
1094 | ||
09041c4b | 1095 | @ifinfo |
c668cdd0 EZ |
1096 | @c This uses ``colon'' instead of a literal `:' because Info cannot |
1097 | @c cope with a `:' in a menu | |
1098 | @kindex M-@key{colon} | |
09041c4b EZ |
1099 | @end ifinfo |
1100 | @ifnotinfo | |
1101 | @kindex M-: | |
1102 | @end ifnotinfo | |
6bf7aab6 DL |
1103 | @findex eval-expression |
1104 | @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating | |
1105 | a Lisp expression interactively. It reads the expression using the | |
1106 | minibuffer, so you can execute any expression on a buffer regardless of | |
1107 | what the buffer contains. When the expression is evaluated, the current | |
1108 | buffer is once again the buffer that was current when @kbd{M-:} was | |
1109 | typed. | |
1110 | ||
1111 | @kindex C-M-x @r{(Emacs-Lisp mode)} | |
1112 | @findex eval-defun | |
1113 | In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command | |
1114 | @code{eval-defun}, which parses the defun containing or following point | |
1115 | as a Lisp expression and evaluates it. The value is printed in the echo | |
1116 | area. This command is convenient for installing in the Lisp environment | |
1117 | changes that you have just made in the text of a function definition. | |
1118 | ||
1119 | @kbd{C-M-x} treats @code{defvar} expressions specially. Normally, | |
1120 | evaluating a @code{defvar} expression does nothing if the variable it | |
1121 | defines already has a value. But @kbd{C-M-x} unconditionally resets the | |
1122 | variable to the initial value specified in the @code{defvar} expression. | |
9c8599ca | 1123 | @code{defcustom} expressions are treated similarly. |
6bf7aab6 | 1124 | This special feature is convenient for debugging Lisp programs. |
dc134342 JL |
1125 | Typing @kbd{C-M-x} on a @code{defface} expression reinitializes |
1126 | the face according to the @code{defface} specification. | |
6bf7aab6 DL |
1127 | |
1128 | @kindex C-x C-e | |
1129 | @findex eval-last-sexp | |
1130 | The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp | |
1131 | expression preceding point in the buffer, and displays the value in the | |
1132 | echo area. It is available in all major modes, not just Emacs-Lisp | |
1133 | mode. It does not treat @code{defvar} specially. | |
1134 | ||
ed4389af RS |
1135 | When the result of an evaluation is an integer, you can type |
1136 | @kbd{C-x C-e} a second time to display the value of the integer result | |
1137 | in additional formats (octal, hexadecimal, and character). | |
1138 | ||
6bf7aab6 DL |
1139 | If @kbd{C-M-x}, @kbd{C-x C-e}, or @kbd{M-:} is given a numeric |
1140 | argument, it inserts the value into the current buffer at point, rather | |
1141 | than displaying it in the echo area. The argument's value does not | |
1142 | matter. | |
1143 | ||
1144 | @findex eval-region | |
1145 | @findex eval-current-buffer | |
1146 | The most general command for evaluating Lisp expressions from a buffer | |
1147 | is @code{eval-region}. @kbd{M-x eval-region} parses the text of the | |
1148 | region as one or more Lisp expressions, evaluating them one by one. | |
1149 | @kbd{M-x eval-current-buffer} is similar but evaluates the entire | |
1150 | buffer. This is a reasonable way to install the contents of a file of | |
58fa012d | 1151 | Lisp code that you are ready to test. Later, as you find bugs and |
6bf7aab6 DL |
1152 | change individual functions, use @kbd{C-M-x} on each function that you |
1153 | change. This keeps the Lisp world in step with the source file. | |
1154 | ||
9c8599ca DL |
1155 | @vindex eval-expression-print-level |
1156 | @vindex eval-expression-print-length | |
1157 | @vindex eval-expression-debug-on-error | |
1158 | The customizable variables @code{eval-expression-print-level} and | |
1159 | @code{eval-expression-print-length} control the maximum depth and length | |
1160 | of lists to print in the result of the evaluation commands before | |
1161 | abbreviating them. @code{eval-expression-debug-on-error} controls | |
1162 | whether evaluation errors invoke the debugger when these commands are | |
1163 | used. | |
1164 | ||
6bf7aab6 DL |
1165 | @node Lisp Interaction |
1166 | @section Lisp Interaction Buffers | |
1167 | ||
1168 | The buffer @samp{*scratch*} which is selected when Emacs starts up is | |
1169 | provided for evaluating Lisp expressions interactively inside Emacs. | |
1170 | ||
1171 | The simplest way to use the @samp{*scratch*} buffer is to insert Lisp | |
1172 | expressions and type @kbd{C-j} after each expression. This command | |
1173 | reads the Lisp expression before point, evaluates it, and inserts the | |
1174 | value in printed representation before point. The result is a complete | |
1175 | typescript of the expressions you have evaluated and their values. | |
1176 | ||
1177 | The @samp{*scratch*} buffer's major mode is Lisp Interaction mode, which | |
1178 | is the same as Emacs-Lisp mode except for the binding of @kbd{C-j}. | |
1179 | ||
1180 | @findex lisp-interaction-mode | |
1181 | The rationale for this feature is that Emacs must have a buffer when | |
1182 | it starts up, but that buffer is not useful for editing files since a | |
1183 | new buffer is made for every file that you visit. The Lisp interpreter | |
1184 | typescript is the most useful thing I can think of for the initial | |
1185 | buffer to do. Type @kbd{M-x lisp-interaction-mode} to put the current | |
1186 | buffer in Lisp Interaction mode. | |
1187 | ||
1188 | @findex ielm | |
1189 | An alternative way of evaluating Emacs Lisp expressions interactively | |
1190 | is to use Inferior Emacs-Lisp mode, which provides an interface rather | |
1191 | like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp | |
1192 | expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer | |
1193 | which uses this mode. | |
1194 | ||
1195 | @node External Lisp | |
1196 | @section Running an External Lisp | |
1197 | ||
1198 | Emacs has facilities for running programs in other Lisp systems. You can | |
1199 | run a Lisp process as an inferior of Emacs, and pass expressions to it to | |
1200 | be evaluated. You can also pass changed function definitions directly from | |
1201 | the Emacs buffers in which you edit the Lisp programs to the inferior Lisp | |
1202 | process. | |
1203 | ||
1204 | @findex run-lisp | |
1205 | @vindex inferior-lisp-program | |
1206 | @kindex C-x C-z | |
1207 | To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs | |
1208 | the program named @code{lisp}, the same program you would run by typing | |
1209 | @code{lisp} as a shell command, with both input and output going through | |
1210 | an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal | |
1211 | output'' from Lisp will go into the buffer, advancing point, and any | |
1212 | ``terminal input'' for Lisp comes from text in the buffer. (You can | |
1213 | change the name of the Lisp executable file by setting the variable | |
1214 | @code{inferior-lisp-program}.) | |
1215 | ||
1216 | To give input to Lisp, go to the end of the buffer and type the input, | |
1217 | terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp | |
1218 | mode, which combines the special characteristics of Lisp mode with most | |
1219 | of the features of Shell mode (@pxref{Shell Mode}). The definition of | |
1220 | @key{RET} to send a line to a subprocess is one of the features of Shell | |
1221 | mode. | |
1222 | ||
1223 | @findex lisp-mode | |
1224 | For the source files of programs to run in external Lisps, use Lisp | |
1225 | mode. This mode can be selected with @kbd{M-x lisp-mode}, and is used | |
1226 | automatically for files whose names end in @file{.l}, @file{.lsp}, or | |
1227 | @file{.lisp}, as most Lisp systems usually expect. | |
1228 | ||
1229 | @kindex C-M-x @r{(Lisp mode)} | |
1230 | @findex lisp-eval-defun | |
1231 | When you edit a function in a Lisp program you are running, the easiest | |
1232 | way to send the changed definition to the inferior Lisp process is the key | |
1233 | @kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun}, | |
1234 | which finds the defun around or following point and sends it as input to | |
1235 | the Lisp process. (Emacs can send input to any inferior process regardless | |
1236 | of what buffer is current.) | |
1237 | ||
1238 | Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing programs | |
1239 | to be run in another Lisp system) and Emacs-Lisp mode (for editing Lisp | |
1240 | programs to be run in Emacs): in both modes it has the effect of installing | |
1241 | the function definition that point is in, but the way of doing so is | |
1242 | different according to where the relevant Lisp environment is found. | |
1243 | @xref{Executing Lisp}. | |
ab5796a9 MB |
1244 | |
1245 | @ignore | |
1246 | arch-tag: 9c3c2f71-b332-4144-8500-3ff9945a50ed | |
1247 | @end ignore |