Contents|Index|Previous|Next

Getting help

You can always ask GDB itself for information on its commands, using the command, help.

help

h
You can use help (abbreviated h) with no arguments to display a short list of named classes of commands like the following example output.

    (gdb) help List of classes of commands:

    running -- Running the program
    stack -- Examining the stack
    data -- Examining data
    breakpoints -- Making program stop at certain points
    files -- Specifying and examining files
    status -- Status inquiries
    support -- Support facilities
    user-defined -- User-defined commands
    aliases -- Aliases of other commands
    obscure -- Obscure features

    Type help followed by a class name for a list of commands
    in that class. Type help followed by command name for full
    documentation. Command name abbreviations are allowed if
    unambiguous. (gdb)

help class
Using one of the general help classes as an argument, you can get a list of the individual commands in that class. For example, here is the help display for the class, status:

    (gdb) help status Status inquiries.

    List of commands:

    show -- Generic command for showing things set with set
    info -- Generic command for printing status

    Type help followed by command name for full documentation.
    Command name abbreviations are allowed if unambiguous.
    (gdb)

help command
With a command name as help argument, GDB displays a short paragraph on how to use that command.

complete args
The complete args command lists all the possible completions for the beginning of a command. Use args to specify the beginning of the command you want completed. For example: complete i results in the following.

info
inspect
ignore

This command is intentionally for use by GNU Emacs.

In addition to help, you can use the GDB commands info and show to inquire about the state of your program, or the state of GDB itself. Each command supports many topics of inquiry; this manual introduces each of them in the appropriate context. The listings under info and under show in the Index point to all the subcommands. See Index in Debugging with GDB.

info
This command (abbreviated i) is for describing the state of your program. For example, you can list the arguments given to your program with info args, list the registers currently in use with info registers, or list the breakpoints you have set with info breakpoints. You can get a complete list of the info subcommands with help info.

set
You can assign the result of an expresson to an environment variable with set. For example, you can set the GDB prompt to a $-sign with set prompt $.

show
In contrast to info, show is for describing the state of GDB itself. You can change most of the things you can show, by using the related command, set; for example, you can control what number system is used for displays with set radix,or simply inquire which is currently in use with show radix.

To display all the settable parameters and their current values, you can use show with no arguments; you may also use info set. Both commands produce the same display.

The following are three miscellaneous show subcommands, all of which are exceptional in lacking corresponding set commands.

show version
Show what version of GDB is running. You should include this information in GDB bug reports. If multiple versions of GDB are in use at your site, you may occasionally want to determine which version of GDB you are running; as GDB evolves, new commands are introduced, and old ones may wither away. The version number is also announced when you start GDB.

show copying
Display information about permission for copying GDB.

show warranty
Display the GNU NO WARRANTY statement (see Figure 2 in GDB Graphical User Interface.