gdb.texinfo

这个是LINUX下的GDB调度工具的源码

completion on an overloaded symbol.

For more information about overloaded functions, see @ref{C plus plus
expressions, ,C@t{++} expressions}.  You can use the command @code{set
overload-resolution off} to disable overload resolution;
see @ref{Debugging C plus plus, ,@value{GDBN} features for C@t{++}}.


@node Help
@section Getting help
@cindex online documentation
@kindex help

You can always ask @value{GDBN} itself for information on its commands,
using the command @code{help}.

@table @code
@kindex h @r{(@code{help})}
@item help
@itemx h
You can use @code{help} (abbreviated @code{h}) with no arguments to
display a short list of named classes of commands:

@smallexample
(@value{GDBP}) help
List of classes of commands:

aliases -- Aliases of other commands
breakpoints -- Making program stop at certain points
data -- Examining data
files -- Specifying and examining files
internals -- Maintenance commands
obscure -- Obscure features
running -- Running the program
stack -- Examining the stack
status -- Status inquiries
support -- Support facilities
tracepoints -- Tracing of program execution without@*
               stopping the program
user-defined -- User-defined commands

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.
(@value{GDBP})
@end smallexample
@c the above line break eliminates huge line overfull...

@item help @var{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 @code{status}:

@smallexample
(@value{GDBP}) help status
Status inquiries.

List of commands:

@c Line break in "show" line falsifies real output, but needed
@c to fit in smallbook page size.
info -- Generic command for showing things
 about the program being debugged
show -- Generic command for showing things
 about the debugger

Type "help" followed by command name for full
documentation.
Command name abbreviations are allowed if unambiguous.
(@value{GDBP})
@end smallexample

@item help @var{command}
With a command name as @code{help} argument, @value{GDBN} displays a
short paragraph on how to use that command.

@kindex apropos
@item apropos @var{args}
The @code{apropos @var{args}} command searches through all of the @value{GDBN}
commands, and their documentation, for the regular expression specified in
@var{args}. It prints out all matches found. For example:

@smallexample
apropos reload
@end smallexample

@noindent
results in:

@smallexample
@c @group
set symbol-reloading -- Set dynamic symbol table reloading
                                 multiple times in one run
show symbol-reloading -- Show dynamic symbol table reloading
                                 multiple times in one run
@c @end group
@end smallexample

@kindex complete
@item complete @var{args}
The @code{complete @var{args}} command lists all the possible completions
for the beginning of a command.  Use @var{args} to specify the beginning of the
command you want completed.  For example:

@smallexample
complete i
@end smallexample

@noindent results in:

@smallexample
@group
if
ignore
info
inspect
@end group
@end smallexample

@noindent This is intended for use by @sc{gnu} Emacs.
@end table

In addition to @code{help}, you can use the @value{GDBN} commands @code{info}
and @code{show} to inquire about the state of your program, or the state
of @value{GDBN} itself.  Each command supports many topics of inquiry; this
manual introduces each of them in the appropriate context.  The listings
under @code{info} and under @code{show} in the Index point to
all the sub-commands.  @xref{Index}.

@c @group
@table @code
@kindex info
@kindex i @r{(@code{info})}
@item info
This command (abbreviated @code{i}) is for describing the state of your
program.  For example, you can list the arguments given to your program
with @code{info args}, list the registers currently in use with @code{info
registers}, or list the breakpoints you have set with @code{info breakpoints}.
You can get a complete list of the @code{info} sub-commands with
@w{@code{help info}}.

@kindex set
@item set
You can assign the result of an expression to an environment variable with
@code{set}.  For example, you can set the @value{GDBN} prompt to a $-sign with
@code{set prompt $}.

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

@kindex info set
To display all the settable parameters and their current
values, you can use @code{show} with no arguments; you may also use
@code{info set}.  Both commands produce the same display.
@c FIXME: "info set" violates the rule that "info" is for state of
@c FIXME...program.  Ck w/ GNU: "info set" to be called something else,
@c FIXME...or change desc of rule---eg "state of prog and debugging session"?
@end table
@c @end group

Here are three miscellaneous @code{show} subcommands, all of which are
exceptional in lacking corresponding @code{set} commands:

@table @code
@kindex show version
@cindex version number
@item show version
Show what version of @value{GDBN} is running.  You should include this
information in @value{GDBN} bug-reports.  If multiple versions of
@value{GDBN} are in use at your site, you may need to determine which
version of @value{GDBN} you are running; as @value{GDBN} evolves, new
commands are introduced, and old ones may wither away.  Also, many
system vendors ship variant versions of @value{GDBN}, and there are
variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well.
The version number is the same as the one announced when you start
@value{GDBN}.

@kindex show copying
@item show copying
Display information about permission for copying @value{GDBN}.

@kindex show warranty
@item show warranty
Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty,
if your version of @value{GDBN} comes with one.

@end table

@node Running
@chapter Running Programs Under @value{GDBN}

When you run a program under @value{GDBN}, you must first generate
debugging information when you compile it.

You may start @value{GDBN} with its arguments, if any, in an environment
of your choice.  If you are doing native debugging, you may redirect
your program's input and output, debug an already running process, or
kill a child process.

@menu
* Compilation::                 Compiling for debugging
* Starting::                    Starting your program
* Arguments::                   Your program's arguments
* Environment::                 Your program's environment

* Working Directory::           Your program's working directory
* Input/Output::                Your program's input and output
* Attach::                      Debugging an already-running process
* Kill Process::                Killing the child process

* Threads::                     Debugging programs with multiple threads
* Processes::                   Debugging programs with multiple processes
@end menu

@node Compilation
@section Compiling for debugging

In order to debug a program effectively, you need to generate
debugging information when you compile it.  This debugging information
is stored in the object file; it describes the data type of each
variable or function and the correspondence between source line numbers
and addresses in the executable code.

To request debugging information, specify the @samp{-g} option when you run
the compiler.

Most compilers do not include information about preprocessor macros in
the debugging information if you specify the @option{-g} flag alone,
because this information is rather large.  Version 3.1 of @value{NGCC},
the @sc{gnu} C compiler, provides macro information if you specify the
options @option{-gdwarf-2} and @option{-g3}; the former option requests
debugging information in the Dwarf 2 format, and the latter requests
``extra information''.  In the future, we hope to find more compact ways
to represent macro information, so that it can be included with
@option{-g} alone.

Many C compilers are unable to handle the @samp{-g} and @samp{-O}
options together.  Using those compilers, you cannot generate optimized
executables containing debugging information.

@value{NGCC}, the @sc{gnu} C compiler, supports @samp{-g} with or
without @samp{-O}, making it possible to debug optimized code.  We
recommend that you @emph{always} use @samp{-g} whenever you compile a
program.  You may think your program is correct, but there is no sense
in pushing your luck.

@cindex optimized code, debugging
@cindex debugging optimized code
When you debug a program compiled with @samp{-g -O}, remember that the
optimizer is rearranging your code; the debugger shows you what is
really there.  Do not be too surprised when the execution path does not
exactly match your source file!  An extreme example: if you define a
variable, but never use it, @value{GDBN} never sees that
variable---because the compiler optimizes it out of existence.

Some things do not work as well with @samp{-g -O} as with just
@samp{-g}, particularly on machines with instruction scheduling.  If in
doubt, recompile with @samp{-g} alone, and if this fixes the problem,
please report it to us as a bug (including a test case!).
@xref{Variables}, for more information about debugging optimized code.

Older versions of the @sc{gnu} C compiler permitted a variant option
@w{@samp{-gg}} for debugging information.  @value{GDBN} no longer supports this
format; if your @sc{gnu} C compiler has this option, do not use it.

@need 2000
@node Starting
@section Starting your program
@cindex starting
@cindex running

@table @code
@kindex run
@kindex r @r{(@code{run})}
@item run
@itemx r
Use the @code{run} command to start your program under @value{GDBN}.
You must first specify the program name (except on VxWorks) with an
argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of
@value{GDBN}}), or by using the @code{file} or @code{exec-file} command
(@pxref{Files, ,Commands to specify files}).

@end table

If you are running your program in an execution environment that
supports processes, @code{run} creates an inferior process and makes
that process run your program.  (In environments without processes,
@code{run} jumps to the start of your program.)

The execution of a program is affected by certain information it
receives from its superior.  @value{GDBN} provides ways to specify this
information, which you must do @emph{before} starting your program.  (You
can change it after starting your program, but such changes only affect
your program the next time you start it.)  This information may be
divided into four categories:

@table @asis
@item The @emph{arguments.}
Specify the arguments to give your program as the arguments of the
@code{run} command.  If a shell is available on your target, the shell
is used to pass the arguments, so that you may use normal conventions
(such as wildcard expansion or variable substitution) in describing
the arguments.
In Unix systems, you can control which shell is used with the
@code{SHELL} environment variable.
@xref{Arguments, ,Your program's arguments}.

@item The @emph{environment.}
Your program normally inherits its environment from @value{GDBN}, but you can
use the @value{GDBN} commands @code{set environment} and @code{unset
environment} to change parts of the environment that affect
your program.  @xref{Environment, ,Your program's environment}.

@item The @emph{working directory.}
Your program inherits its working directory from @value{GDBN}.  You can set
the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}.
@xref{Working Directory, ,Your program's working directory}.

@item The @emph{standard input and output.}
Your program normally uses the same device for standard input and
standard output as @value{GDBN} is using.  You can redirect input and output
in the @code{run} command line, or you can use the @code{tty} command to
set a different device for your program.
@xref{Input/Output, ,Your program's input and output}.

@cindex pipes
@emph{Warning:} While input and output redirection work, you cannot use
pipes to pass the output of the program you are debugging to another
program; if you attempt this, @value{GDBN} is likely to wind up debugging the
wrong program.
@end table

When you issue the @code{run} command, your program begins to execute
immediately.  @xref{Stopping, ,Stopping and continuing}, for discussion
of how to arrange for your program to stop.  Once your program has
stopped, you may call functions in your program, using the @code{print}
or @code{call} commands.  @xref{Data, ,Examining Data}.

If the modification time of your symbol file has changed since the last
time @value{GDBN} read its symbols, @val