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NAMEgdb - The GNU DebuggerSYNOPSISgdb [-help] [-nh] [-nx] [-q] [-batch] [-cd=dir] [-f] [-b bps] [-tty=dev] [-s symfile] [-e prog] [-se prog] [-c core] [-p procID] [-x cmds] [-d dir] [prog|prog procID|prog core]DESCRIPTIONThe 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:
You can use GDB to debug programs written in C, C++, Fortran and Modula-2. 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 or use option "-p", if you want to debug a running process: gdb program 1234 gdb -p 1234 would attach GDB to process 1234. With option -p you can omit the program filename. Here are some of the most frequently needed GDB commands:
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. OPTIONSAny 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.
SEE ALSOThe 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 commandinfo 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. COPYRIGHTCopyright (c) 1988-2022 Free Software Foundation, Inc.Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Free Software" and "Free Software Needs Free Documentation", with the Front-Cover Texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. (a) The FSF's Back-Cover Text is: "You are free to copy and modify this GNU Manual. Buying copies from GNU Press supports the FSF in developing GNU and promoting software freedom."
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