gdb/gdb.1

   1 .\" Copyright 1991, 1999 Free Software Foundation, Inc.
   2 .\" See section COPYING for conditions for redistribution
   3 .\" $Id$
   4 .TH gdb 1 "4nov1991" "GNU Tools" "GNU Tools"
   5 .SH NAME
   6 gdb \- The GNU Debugger
   7 .SH SYNOPSIS
   8 .na
   9 .TP
  10 .B gdb
  11 .RB "[\|" \-help "\|]"
  12 .RB "[\|" \-nx "\|]"
  13 .RB "[\|" \-q "\|]"
  14 .RB "[\|" \-batch "\|]"
  15 .RB "[\|" \-cd=\c
  16 .I dir\c
  17 \|]
  18 .RB "[\|" \-f "\|]"
  19 .RB "[\|" "\-b\ "\c
  20 .IR bps "\|]"
  21 .RB "[\|" "\-tty="\c
  22 .IR dev "\|]"
  23 .RB "[\|" "\-s "\c
  24 .I symfile\c
  25 \&\|]
  26 .RB "[\|" "\-e "\c
  27 .I prog\c
  28 \&\|]
  29 .RB "[\|" "\-se "\c
  30 .I prog\c
  31 \&\|]
  32 .RB "[\|" "\-c "\c
  33 .I core\c
  34 \&\|]
  35 .RB "[\|" "\-x "\c
  36 .I cmds\c
  37 \&\|]
  38 .RB "[\|" "\-d "\c
  39 .I dir\c
  40 \&\|]
  41 .RB "[\|" \c
  42 .I prog\c
  43 .RB "[\|" \c
  44 .IR core \||\| procID\c
  45 \&\|]\&\|]
  46 .ad b
  47 .SH DESCRIPTION
  48 The purpose of a debugger such as GDB is to allow you to see what is
  49 going on ``inside'' another program while it executes\(em\&or what another
  50 program was doing at the moment it crashed.
  51
  52 GDB can do four main kinds of things (plus other things in support of
  53 these) to help you catch bugs in the act:
  54
  55 .TP
  56 \ \ \ \(bu
  57 Start your program, specifying anything that might affect its behavior.
  58
  59 .TP
  60 \ \ \ \(bu
  61 Make your program stop on specified conditions.
  62
  63 .TP
  64 \ \ \ \(bu
  65 Examine what has happened, when your program has stopped.
  66
  67 .TP
  68 \ \ \ \(bu
  69 Change things in your program, so you can experiment with correcting the
  70 effects of one bug and go on to learn about another.
  71 .PP
  72
  73 You can use GDB to debug programs written in C, C++, and Modula-2.
  74 Fortran support will be added when a GNU Fortran compiler is ready.
  75
  76 GDB is invoked with the shell command \c
  77 .B gdb\c
  78 \&.  Once started, it reads
  79 commands from the terminal until you tell it to exit with the GDB
  80 command \c
  81 .B quit\c
  82 \&.  You can get online help from \c
  83 .B gdb\c
  84 \& itself
  85 by using the command \c
  86 .B help\c
  87 \&.
  88
  89 You can run \c
  90 .B gdb\c
  91 \& with no arguments or options; but the most
  92 usual way to start GDB is with one argument or two, specifying an
  93 executable program as the argument:
  94 .sp
  95 .br
  96 gdb\ program
  97 .br
  98 .sp
  99
 100 You can also start with both an executable program and a core file specified:
 101 .sp
 102 .br
 103 gdb\ program\ core
 104 .br
 105 .sp
 106
 107 You can, instead, specify a process ID as a second argument, if you want
 108 to debug a running process:
 109 .sp
 110 .br
 111 gdb\ program\ 1234
 112 .br
 113 .sp
 114
 115 would attach GDB to process \c
 116 .B 1234\c
 117 \& (unless you also have a file
 118 named `\|\c
 119 .B 1234\c
 120 \&\|'; GDB does check for a core file first).
 121
 122 Here are some of the most frequently needed GDB commands:
 123 .TP
 124 .B break \fR[\|\fIfile\fB:\fR\|]\fIfunction
 125 \&
 126 Set a breakpoint at \c
 127 .I function\c
 128 \& (in \c
 129 .I file\c
 130 \&).
 131 .TP
 132 .B run \fR[\|\fIarglist\fR\|]
 133 Start your program (with \c
 134 .I arglist\c
 135 \&, if specified).
 136 .TP
 137 .B bt
 138 Backtrace: display the program stack.
 139 .TP
 140 .BI print " expr"\c
 141 \&
 142 Display the value of an expression.
 143 .TP
 144 .B c
 145 Continue running your program (after stopping, e.g. at a breakpoint).
 146 .TP
 147 .B next
 148 Execute next program line (after stopping); step \c
 149 .I over\c
 150 \& any
 151 function calls in the line.
 152 .TP
 153 .B step
 154 Execute next program line (after stopping); step \c
 155 .I into\c
 156 \& any
 157 function calls in the line.
 158 .TP
 159 .B help \fR[\|\fIname\fR\|]
 160 Show information about GDB command \c
 161 .I name\c
 162 \&, or general information
 163 about using GDB.
 164 .TP
 165 .B quit
 166 Exit from GDB.
 167 .PP
 168 For full details on GDB, see \c
 169 .I
 170 Using GDB: A Guide to the GNU Source-Level Debugger\c
 171 \&, by Richard M. Stallman and Roland H. Pesch.  The same text is available online
 172 as the \c
 173 .B gdb\c
 174 \& entry in the \c
 175 .B info\c
 176 \& program.
 177 .SH OPTIONS
 178 Any arguments other than options specify an executable
 179 file and core file (or process ID); that is, the first argument
 180 encountered with no
 181 associated option flag is equivalent to a `\|\c
 182 .B \-se\c
 183 \&\|' option, and the
 184 second, if any, is equivalent to a `\|\c
 185 .B \-c\c
 186 \&\|' option if it's the name of a file.  Many options have
 187 both long and short forms; both are shown here.  The long forms are also
 188 recognized if you truncate them, so long as enough of the option is
 189 present to be unambiguous.  (If you prefer, you can flag option
 190 arguments with `\|\c
 191 .B +\c
 192 \&\|' rather than `\|\c
 193 .B \-\c
 194 \&\|', though we illustrate the
 195 more usual convention.)
 196
 197 All the options and command line arguments you give are processed
 198 in sequential order.  The order makes a difference when the
 199 `\|\c
 200 .B \-x\c
 201 \&\|' option is used.
 202
 203 .TP
 204 .B \-help
 205 .TP
 206 .B \-h
 207 List all options, with brief explanations.
 208
 209 .TP
 210 .BI "\-symbols=" "file"\c
 211 .TP
 212 .BI "\-s " "file"\c
 213 \&
 214 Read symbol table from file \c
 215 .I file\c
 216 \&.
 217
 218 .TP
 219 .B \-write
 220 Enable writing into executable and core files.
 221
 222 .TP
 223 .BI "\-exec=" "file"\c
 224 .TP
 225 .BI "\-e " "file"\c
 226 \&
 227 Use file \c
 228 .I file\c
 229 \& as the executable file to execute when
 230 appropriate, and for examining pure data in conjunction with a core
 231 dump.
 232
 233 .TP
 234 .BI "\-se=" "file"\c
 235 \&
 236 Read symbol table from file \c
 237 .I file\c
 238 \& and use it as the executable
 239 file.
 240
 241 .TP
 242 .BI "\-core=" "file"\c
 243 .TP
 244 .BI "\-c " "file"\c
 245 \&
 246 Use file \c
 247 .I file\c
 248 \& as a core dump to examine.
 249
 250 .TP
 251 .BI "\-command=" "file"\c
 252 .TP
 253 .BI "\-x " "file"\c
 254 \&
 255 Execute GDB commands from file \c
 256 .I file\c
 257 \&.
 258
 259 .TP
 260 .BI "\-directory=" "directory"\c
 261 .TP
 262 .BI "\-d " "directory"\c
 263 \&
 264 Add \c
 265 .I directory\c
 266 \& to the path to search for source files.
 267 .PP
 268
 269 .TP
 270 .B \-nx
 271 .TP
 272 .B \-n
 273 Do not execute commands from any `\|\c
 274 .B .gdbinit\c
 275 \&\|' initialization files.
 276 Normally, the commands in these files are executed after all the
 277 command options and arguments have been processed.
 278
 279
 280 .TP
 281 .B \-quiet
 282 .TP
 283 .B \-q
 284 ``Quiet''.  Do not print the introductory and copyright messages.  These
 285 messages are also suppressed in batch mode.
 286
 287 .TP
 288 .B \-batch
 289 Run in batch mode.  Exit with status \c
 290 .B 0\c
 291 \& after processing all the command
 292 files specified with `\|\c
 293 .B \-x\c
 294 \&\|' (and `\|\c
 295 .B .gdbinit\c
 296 \&\|', if not inhibited).
 297 Exit with nonzero status if an error occurs in executing the GDB
 298 commands in the command files.
 299
 300 Batch mode may be useful for running GDB as a filter, for example to
 301 download and run a program on another computer; in order to make this
 302 more useful, the message
 303 .sp
 304 .br
 305 Program\ exited\ normally.
 306 .br
 307 .sp
 308
 309 (which is ordinarily issued whenever a program running under GDB control
 310 terminates) is not issued when running in batch mode.
 311
 312 .TP
 313 .BI "\-cd=" "directory"\c
 314 \&
 315 Run GDB using \c
 316 .I directory\c
 317 \& as its working directory,
 318 instead of the current directory.
 319
 320 .TP
 321 .B \-fullname
 322 .TP
 323 .B \-f
 324 Emacs sets this option when it runs GDB as a subprocess.  It tells GDB
 325 to output the full file name and line number in a standard,
 326 recognizable fashion each time a stack frame is displayed (which
 327 includes each time the program stops).  This recognizable format looks
 328 like two `\|\c
 329 .B \032\c
 330 \&\|' characters, followed by the file name, line number
 331 and character position separated by colons, and a newline.  The
 332 Emacs-to-GDB interface program uses the two `\|\c
 333 .B \032\c
 334 \&\|' characters as
 335 a signal to display the source code for the frame.
 336
 337 .TP
 338 .BI "\-b " "bps"\c
 339 \&
 340 Set the line speed (baud rate or bits per second) of any serial
 341 interface used by GDB for remote debugging.
 342
 343 .TP
 344 .BI "\-tty=" "device"\c
 345 \&
 346 Run using \c
 347 .I device\c
 348 \& for your program's standard input and output.
 349 .PP
 350
 351 .SH "SEE ALSO"
 352 .RB "`\|" gdb "\|'"
 353 entry in
 354 .B info\c
 355 \&;
 356 .I
 357 Using GDB: A Guide to the GNU Source-Level Debugger\c
 358 , Richard M. Stallman and Roland H. Pesch, July 1991.
 359 .SH COPYING
 360 Copyright (c) 1991 Free Software Foundation, Inc.
 361 .PP
 362 Permission is granted to make and distribute verbatim copies of
 363 this manual provided the copyright notice and this permission notice
 364 are preserved on all copies.
 365 .PP
 366 Permission is granted to copy and distribute modified versions of this
 367 manual under the conditions for verbatim copying, provided that the
 368 entire resulting derived work is distributed under the terms of a
 369 permission notice identical to this one.
 370 .PP
 371 Permission is granted to copy and distribute translations of this
 372 manual into another language, under the above conditions for modified
 373 versions, except that this permission notice may be included in
 374 translations approved by the Free Software Foundation instead of in
 375 the original English.