NAME

       gdb - The GNU Debugger

SYNOPSIS

       gdb    [-help] [-nh] [-nx] [-q] [-batch] [-cd=dir] [-f] [-b bps] [-tty=dev] [-s symfile] [-e prog] [-se
              prog] [-c core] [-x file] [-ex cmd] [-d dir] [prog [core|procID]]

       gdb    [options] --args prog [arguments]

       gdbtui [options]

DESCRIPTION

       The purpose of a debugger such as GDB is to allow you to see what is going on ``inside'' another  program
       while it executes—or what another program was doing at the moment it crashed.

       GDB  can  do  four main kinds of things (plus other things in support of these) to help you catch bugs in
       the act:

          •   Start your program, specifying anything that might affect its behavior.

          •   Make your program stop on specified conditions.

          •   Examine what has happened, when your program has stopped.

          •   Change things in your program, so you can experiment with correcting the effects of one bug and go
              on to learn about another.

       You  can use GDB to debug programs written in C, C++, and Modula-2.  Fortran support will be added when a
       GNU Fortran compiler is ready.

       GDB is invoked with the shell command gdb.  Once started, it reads commands from the terminal  until  you
       tell  it to exit with the GDB command quit.  You can get online help from gdb itself by using the command
       help.

       You can run gdb with no arguments or options; but the most usual way to start GDB is with one argument or
       two, specifying an executable program as the argument:

       gdb program

       You can also start with both an executable program and a core file specified:

       gdb program core

       You can, instead, specify a process ID as a second argument, if you want to debug a running process:

       gdb program 1234

       would  attach  GDB  to  process 1234 (unless you also have a file named `1234'; GDB does check for a core
       file first).

       Here are some of the most frequently needed GDB commands:

       break [file:]function
               Set a breakpoint at function (in file).

       run [arglist]
              Start your program (with arglist, if specified).

       bt     Backtrace: display the program stack.

       print expr
              Display the value of an expression.

       c      Continue running your program (after stopping, e.g. at a breakpoint).

       next   Execute next program line (after stopping); step over any function calls in the line.

       edit [file:]function
              look at the program line where it is presently stopped.

       list [file:]function
              type the text of the program in the vicinity of where it is presently stopped.

       step   Execute next program line (after stopping); step into any function calls in the line.

       help [name]
              Show information about GDB command name, or general information about using GDB.

       quit   Exit from GDB.

       For full details on GDB, see Using GDB: A Guide to the GNU Source-Level Debugger, by Richard M.  Stallman
       and Roland H. Pesch.  The same text is available online as the gdb entry in the info program.

OPTIONS

       Any  arguments  other than options specify an executable file and core file (or process ID); that is, the
       first argument encountered with no associated option flag is  equivalent  to  a  `-se'  option,  and  the
       second,  if  any, is equivalent to a `-c' option if it's the name of a file.  Many options have both long
       and short forms; both are shown here.  The long forms are also recognized if you truncate them,  so  long
       as enough of the option is present to be unambiguous.  (If you prefer, you can flag option arguments with
       `+' rather than `-', though we illustrate the more usual convention.)

       All the options and command line arguments you give are processed in sequential order.  The order makes a
       difference when the `-x' option is used.

       -help

       -h     List all options, with brief explanations.

       -symbols=file

       -s file
              Read symbol table from file file.

       -write Enable writing into executable and core files.

       -exec=file

       -e file
              Use  file  file as the executable file to execute when appropriate, and for examining pure data in
              conjunction with a core dump.

       -se=file
              Read symbol table from file file and use it as the executable file.

       -core=file

       -c file
              Use file file as a core dump to examine.

       -command=file

       -x file
              Execute GDB commands from file file.

       -ex command
              Execute given GDB command.

       -directory=directory

       -d directory
              Add directory to the path to search for source files.

       -nh    Do not execute commands from ~/.gdbinit.

       -nx

       -n     Do not execute commands from any `.gdbinit' initialization files.

       -quiet

       -q     ``Quiet''.  Do not print the  introductory  and  copyright  messages.   These  messages  are  also
              suppressed in batch mode.

       -batch Run  in batch mode.  Exit with status 0 after processing all the command files specified with `-x'
              (and `.gdbinit', if not inhibited).  Exit with nonzero status if an error occurs in executing  the
              GDB commands in the command files.

              Batch mode may be useful for running GDB as a filter, for example to download and run a program on
              another computer; in order to make this more useful, the message

              Program exited normally.

              (which is ordinarily issued whenever a program running under GDB control terminates) is not issued
              when running in batch mode.

       -cd=directory
              Run GDB using directory as its working directory, instead of the current directory.

       -fullname

       -f     Emacs  sets  this  option  when it runs GDB as a subprocess.  It tells GDB to output the full file
              name and line number in a standard, recognizable fashion each time  a  stack  frame  is  displayed
              (which  includes  each  time  the  program  stops).  This recognizable format looks like two ` 32'
              characters, followed by the file name, line number and character position separated by colons, and
              a  newline.   The  Emacs-to-GDB  interface  program  uses  the two ` 32' characters as a signal to
              display the source code for the frame.

       -b bps Set the line speed (baud rate or bits per second) of any serial interface used by GDB  for  remote
              debugging.

       -tty=device
              Run using device for your program's standard input and output.

       --argsPass arguments after the program name to the program when it is run.

       -tuiRun GDB using a text (console) user interface.

SEE ALSO

       The full documentation for gdb is maintained as a Texinfo manual.  If the info and gdb programs and GDB's
       Texinfo documentation are properly installed at your site, the command

              info gdb

       should give you access to the complete manual.

       Using GDB: A Guide to the GNU Source-Level Debugger, Richard M. Stallman and Roland H. Pesch, July 1991.

COPYING

       Copyright (c) 1991, 2010 Free Software Foundation, Inc.

       Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice
       and this permission notice are preserved on all copies.

       Permission  is  granted  to copy and distribute modified versions of this manual under the conditions for
       verbatim copying, provided that the entire resulting derived work is distributed under  the  terms  of  a
       permission notice identical to this one.

       Permission is granted to copy and distribute translations of this manual into another language, under the
       above conditions  for  modified  versions,  except  that  this  permission  notice  may  be  included  in
       translations approved by the Free Software Foundation instead of in the original English.