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C. Maintenance Commands

In addition to commands intended for No value for GDBN users, No value for GDBN includes a number of commands intended for No value for GDBN developers, that are not documented elsewhere in this manual. These commands are provided here for reference. (For commands that turn on debugging messages, see Optional Messages about Internal Happenings.)

maint agent expression

Translate the given expression into remote agent bytecodes. This command is useful for debugging the Agent Expression mechanism (see section The GDB Agent Expression Mechanism).

maint info breakpoints

Using the same format as ‘info breakpoints’, display both the breakpoints you've set explicitly, and those No value for GDBN is using for internal purposes. Internal breakpoints are shown with negative breakpoint numbers. The type column identifies what kind of breakpoint is shown:


Normal, explicitly set breakpoint.


Normal, explicitly set watchpoint.


Internal breakpoint, used to handle correctly stepping through longjmp calls.

longjmp resume

Internal breakpoint at the target of a longjmp.


Temporary internal breakpoint used by the No value for GDBN until command.


Temporary internal breakpoint used by the No value for GDBN finish command.

shlib events

Shared library events.

maint check-symtabs

Check the consistency of psymtabs and symtabs.

maint cplus first_component name

Print the first C++ class/namespace component of name.

maint cplus namespace

Print the list of possible C++ namespaces.

maint demangle name

Demangle a C++ or Objective-C mangled name.

maint deprecate command [replacement]
maint undeprecate command

Deprecate or undeprecate the named command. Deprecated commands cause No value for GDBN to issue a warning when you use them. The optional argument replacement says which newer command should be used in favor of the deprecated one; if it is given, No value for GDBN will mention the replacement as part of the warning.

maint dump-me

Cause a fatal signal in the debugger and force it to dump its core. This is supported only on systems which support aborting a program with the SIGQUIT signal.

maint internal-error [message-text]
maint internal-warning [message-text]

Cause No value for GDBN to call the internal function internal_error or internal_warning and hence behave as though an internal error or internal warning has been detected. In addition to reporting the internal problem, these functions give the user the opportunity to either quit No value for GDBN or create a core file of the current No value for GDBN session.

These commands take an optional parameter message-text that is used as the text of the error or warning message.

Here's an example of using internal-error:

(No value for GDBP) maint internal-error testing, 1, 2
…/maint.c:121: internal-error: testing, 1, 2
A problem internal to GDB has been detected.  Further
debugging may prove unreliable.
Quit this debugging session? (y or n) n
Create a core file? (y or n) n
(No value for GDBP)
maint packet text

If No value for GDBN is talking to an inferior via the serial protocol, then this command sends the string text to the inferior, and displays the response packet. No value for GDBN supplies the initial ‘$’ character, the terminating ‘#’ character, and the checksum.

maint print architecture [file]

Print the entire architecture configuration. The optional argument file names the file where the output goes.

maint print dummy-frames

Prints the contents of No value for GDBN's internal dummy-frame stack.

(No value for GDBP) b add
(No value for GDBP) print add(2,3)
Breakpoint 2, add (a=2, b=3) at …
58	  return (a + b);
The program being debugged stopped while in a function called from GDB.
(No value for GDBP) maint print dummy-frames
0x1a57c80: pc=0x01014068 fp=0x0200bddc sp=0x0200bdd6
 top=0x0200bdd4 id={stack=0x200bddc,code=0x101405c}
 call_lo=0x01014000 call_hi=0x01014001
(No value for GDBP)

Takes an optional file parameter.

maint print registers [file]
maint print raw-registers [file]
maint print cooked-registers [file]
maint print register-groups [file]

Print No value for GDBN's internal register data structures.

The command maint print raw-registers includes the contents of the raw register cache; the command maint print cooked-registers includes the (cooked) value of all registers; and the command maint print register-groups includes the groups that each register is a member of. See (gdbint)Registers section `Registers' in No value for GDBN Internals.

These commands take an optional parameter, a file name to which to write the information.

maint print reggroups [file]

Print No value for GDBN's internal register group data structures. The optional argument file tells to what file to write the information.

The register groups info looks like this:

(No value for GDBP) maint print reggroups
 Group      Type
 general    user
 float      user
 all        user
 vector     user
 system     user
 save       internal
 restore    internal

This command forces No value for GDBN to flush its internal register cache.

maint print objfiles

Print a dump of all known object files. For each object file, this command prints its name, address in memory, and all of its psymtabs and symtabs.

maint print statistics

This command prints, for each object file in the program, various data about that object file followed by the byte cache (bcache) statistics for the object file. The objfile data includes the number of minimal, partial, full, and stabs symbols, the number of types defined by the objfile, the number of as yet unexpanded psym tables, the number of line tables and string tables, and the amount of memory used by the various tables. The bcache statistics include the counts, sizes, and counts of duplicates of all and unique objects, max, average, and median entry size, total memory used and its overhead and savings, and various measures of the hash table size and chain lengths.

maint print target-stack

A target is an interface between the debugger and a particular kind of file or process. Targets can be stacked in strata, so that more than one target can potentially respond to a request. In particular, memory accesses will walk down the stack of targets until they find a target that is interested in handling that particular address.

This command prints a short description of each layer that was pushed on the target stack, starting from the top layer down to the bottom one.

maint print type expr

Print the type chain for a type specified by expr. The argument can be either a type name or a symbol. If it is a symbol, the type of that symbol is described. The type chain produced by this command is a recursive definition of the data type as stored in No value for GDBN's data structures, including its flags and contained types.

maint set dwarf2 max-cache-age
maint show dwarf2 max-cache-age

Control the DWARF 2 compilation unit cache.

In object files with inter-compilation-unit references, such as those produced by the GCC option ‘-feliminate-dwarf2-dups’, the DWARF 2 reader needs to frequently refer to previously read compilation units. This setting controls how long a compilation unit will remain in the cache if it is not referenced. A higher limit means that cached compilation units will be stored in memory longer, and more total memory will be used. Setting it to zero disables caching, which will slow down No value for GDBN startup, but reduce memory consumption.

maint set profile
maint show profile

Control profiling of No value for GDBN.

Profiling will be disabled until you use the ‘maint set profile’ command to enable it. When you enable profiling, the system will begin collecting timing and execution count data; when you disable profiling or exit No value for GDBN, the results will be written to a log file. Remember that if you use profiling, No value for GDBN will overwrite the profiling log file (often called ‘gmon.out’). If you have a record of important profiling data in a ‘gmon.out’ file, be sure to move it to a safe location.

Configuring with ‘--enable-profiling’ arranges for No value for GDBN to be compiled with the ‘-pg’ compiler option.

maint show-debug-regs

Control whether to show variables that mirror the x86 hardware debug registers. Use ON to enable, OFF to disable. If enabled, the debug registers values are shown when No value for GDBN inserts or removes a hardware breakpoint or watchpoint, and when the inferior triggers a hardware-assisted breakpoint or watchpoint.

maint space

Control whether to display memory usage for each command. If set to a nonzero value, No value for GDBN will display how much memory each command took, following the command's own output. This can also be requested by invoking No value for GDBN with the ‘--statistics’ command-line switch (see section Choosing Modes).

maint time

Control whether to display the execution time for each command. If set to a nonzero value, No value for GDBN will display how much time it took to execute each command, following the command's own output. This can also be requested by invoking No value for GDBN with the ‘--statistics’ command-line switch (see section Choosing Modes).

maint translate-address [section] addr

Find the symbol stored at the location specified by the address addr and an optional section name section. If found, No value for GDBN prints the name of the closest symbol and an offset from the symbol's location to the specified address. This is similar to the info address command (see section Examining the Symbol Table), except that this command also allows to find symbols in other sections.

The following command is useful for non-interactive invocations of No value for GDBN, such as in the test suite.

set watchdog nsec

Set the maximum number of seconds No value for GDBN will wait for the target operation to finish. If this time expires, No value for GDBN reports and error and the command is aborted.

show watchdog

Show the current setting of the target wait timeout.

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