GDB/MI Miscellaneous Commands (Debugging with GDB)

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27.24 Miscellaneous GDB/MI Commands

Synopsis

 -gdb-exit

Exit GDB immediately.

GDB Command

Approximately corresponds to ‘quit’.

Example

(gdb)
-gdb-exit
^exit

Synopsis

 -gdb-set

Set an internal GDB variable.

GDB Command

The corresponding GDB command is ‘set’.

Example

(gdb)
-gdb-set $foo=3
^done
(gdb)

Synopsis

 -gdb-show

Show the current value of a GDB variable.

GDB Command

The corresponding GDB command is ‘show’.

Example

(gdb)
-gdb-show annotate
^done,value="0"
(gdb)

Synopsis

 -gdb-version

Show version information for GDB. Used mostly in testing.

GDB Command

The GDB equivalent is ‘show version’. GDB by default shows this information when you start an interactive session.

Example

(gdb)
-gdb-version
~GNU gdb 5.2.1
~Copyright 2000 Free Software Foundation, Inc.
~GDB is free software, covered by the GNU General Public License, and
~you are welcome to change it and/or distribute copies of it under
~ certain conditions.
~Type "show copying" to see the conditions.
~There is absolutely no warranty for GDB.  Type "show warranty" for
~ details.
~This GDB was configured as
 "--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
^done
(gdb)

Synopsis

-list-thread-groups [ --available ] [ --recurse 1 ] [ group ... ]

Lists thread groups (see Thread groups). When a single thread group is passed as the argument, lists the children of that group. When several thread group are passed, lists information about those thread groups. Without any parameters, lists information about all top-level thread groups.

Normally, thread groups that are being debugged are reported. With the ‘--available’ option, GDB reports thread groups available on the target.

The output of this command may have either a ‘threads’ result or a ‘groups’ result. The ‘thread’ result has a list of tuples as value, with each tuple describing a thread (see GDB/MI Thread Information). The ‘groups’ result has a list of tuples as value, each tuple describing a thread group. If top-level groups are requested (that is, no parameter is passed), or when several groups are passed, the output always has a ‘groups’ result. The format of the ‘group’ result is described below.

To reduce the number of roundtrips it’s possible to list thread groups together with their children, by passing the ‘--recurse’ option and the recursion depth. Presently, only recursion depth of 1 is permitted. If this option is present, then every reported thread group will also include its children, either as ‘group’ or ‘threads’ field.

In general, any combination of option and parameters is permitted, with the following caveats:

• When a single thread group is passed, the output will typically be the ‘threads’ result. Because threads may not contain anything, the ‘recurse’ option will be ignored.
• When the ‘--available’ option is passed, limited information may be available. In particular, the list of threads of a process might be inaccessible. Further, specifying specific thread groups might not give any performance advantage over listing all thread groups. The frontend should assume that ‘-list-thread-groups --available’ is always an expensive operation and cache the results.

The ‘groups’ result is a list of tuples, where each tuple may have the following fields:

id

Identifier of the thread group. This field is always present. The identifier is an opaque string; frontends should not try to convert it to an integer, even though it might look like one.

type

The type of the thread group. At present, only ‘process’ is a valid type.

pid

The target-specific process identifier. This field is only present for thread groups of type ‘process’ and only if the process exists.

exit-code

The exit code of this group’s last exited thread, formatted in octal. This field is only present for thread groups of type ‘process’ and only if the process is not running.

num_children

The number of children this thread group has. This field may be absent for an available thread group.

threads

This field has a list of tuples as value, each tuple describing a thread. It may be present if the ‘--recurse’ option is specified, and it’s actually possible to obtain the threads.

cores

This field is a list of integers, each identifying a core that one thread of the group is running on. This field may be absent if such information is not available.

executable

The name of the executable file that corresponds to this thread group. The field is only present for thread groups of type ‘process’, and only if there is a corresponding executable file.

Example

(gdb)
-list-thread-groups
^done,groups=[{id="17",type="process",pid="yyy",num_children="2"}]
-list-thread-groups 17
^done,threads=[{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
   frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]},state="running"},
{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
   frame={level="0",addr="0x0804891f",func="foo",args=[{name="i",value="10"}],
           file="/tmp/a.c",fullname="/tmp/a.c",line="158",arch="i386:x86_64"},state="running"}]]
-list-thread-groups --available
^done,groups=[{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]}]
-list-thread-groups --available --recurse 1
 ^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
                threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
                         {id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},..]
-list-thread-groups --available --recurse 1 17 18
^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
               threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
                        {id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},...]

Synopsis

-info-os [ type ]

If no argument is supplied, the command returns a table of available operating-system-specific information types. If one of these types is supplied as an argument type, then the command returns a table of data of that type.

The types of information available depend on the target operating system.

GDB Command

The corresponding GDB command is ‘info os’.

Example

When run on a GNU/Linux system, the output will look something like this:

(gdb)
-info-os
^done,OSDataTable={nr_rows="10",nr_cols="3",
hdr=[{width="10",alignment="-1",col_name="col0",colhdr="Type"},
     {width="10",alignment="-1",col_name="col1",colhdr="Description"},
     {width="10",alignment="-1",col_name="col2",colhdr="Title"}],
body=[item={col0="cpus",col1="Listing of all cpus/cores on the system",
            col2="CPUs"},
      item={col0="files",col1="Listing of all file descriptors",
            col2="File descriptors"},
      item={col0="modules",col1="Listing of all loaded kernel modules",
            col2="Kernel modules"},
      item={col0="msg",col1="Listing of all message queues",
            col2="Message queues"},
      item={col0="processes",col1="Listing of all processes",
            col2="Processes"},
      item={col0="procgroups",col1="Listing of all process groups",
            col2="Process groups"},
      item={col0="semaphores",col1="Listing of all semaphores",
            col2="Semaphores"},
      item={col0="shm",col1="Listing of all shared-memory regions",
            col2="Shared-memory regions"},
      item={col0="sockets",col1="Listing of all internet-domain sockets",
            col2="Sockets"},
      item={col0="threads",col1="Listing of all threads",
            col2="Threads"}]
(gdb)
-info-os processes
^done,OSDataTable={nr_rows="190",nr_cols="4",
hdr=[{width="10",alignment="-1",col_name="col0",colhdr="pid"},
     {width="10",alignment="-1",col_name="col1",colhdr="user"},
     {width="10",alignment="-1",col_name="col2",colhdr="command"},
     {width="10",alignment="-1",col_name="col3",colhdr="cores"}],
body=[item={col0="1",col1="root",col2="/sbin/init",col3="0"},
      item={col0="2",col1="root",col2="[kthreadd]",col3="1"},
      item={col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"},
      ...
      item={col0="26446",col1="stan",col2="bash",col3="0"},
      item={col0="28152",col1="stan",col2="bash",col3="1"}]}
(gdb)

(Note that the MI output here includes a "Title" column that does not appear in command-line info os; this column is useful for MI clients that want to enumerate the types of data, such as in a popup menu, but is needless clutter on the command line, and info os omits it.)

Synopsis

-add-inferior

Creates a new inferior (see Inferiors Connections and Programs). The created inferior is not associated with any executable. Such association may be established with the ‘-file-exec-and-symbols’ command (see GDB/MI File Commands). The command response has a single field, ‘inferior’, whose value is the identifier of the thread group corresponding to the new inferior.

Example

(gdb)
-add-inferior
^done,inferior="i3"

Synopsis

-interpreter-exec interpreter command

Execute the specified command in the given interpreter.

GDB Command

The corresponding GDB command is ‘interpreter-exec’.

Example

(gdb)
-interpreter-exec console "break main"
&"During symbol reading, couldn't parse type; debugger out of date?.\n"
&"During symbol reading, bad structure-type format.\n"
~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
^done
(gdb)

Synopsis

-inferior-tty-set /dev/pts/1

Set terminal for future runs of the program being debugged.

GDB Command

The corresponding GDB command is ‘set inferior-tty’ /dev/pts/1.

Example

(gdb)
-inferior-tty-set /dev/pts/1
^done
(gdb)

Synopsis

-inferior-tty-show

Show terminal for future runs of program being debugged.

GDB Command

The corresponding GDB command is ‘show inferior-tty’.

Example

(gdb)
-inferior-tty-set /dev/pts/1
^done
(gdb)
-inferior-tty-show
^done,inferior_tty_terminal="/dev/pts/1"
(gdb)

Synopsis

-enable-timings [yes | no]

Toggle the printing of the wallclock, user and system times for an MI command as a field in its output. This command is to help frontend developers optimize the performance of their code. No argument is equivalent to ‘yes’.

GDB Command

No equivalent.

Example

(gdb)
-enable-timings
^done
(gdb)
-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x080484ed",func="main",file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73",thread-groups=["i1"],
times="0"},
time={wallclock="0.05185",user="0.00800",system="0.00000"}
(gdb)
-enable-timings no
^done
(gdb)
-exec-run
^running
(gdb)
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
frame={addr="0x080484ed",func="main",args=[{name="argc",value="1"},
{name="argv",value="0xbfb60364"}],file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73",arch="i386:x86_64"}
(gdb)

Synopsis

-complete command

Show a list of completions for partially typed CLI command.

This command is intended for GDB/MI frontends that cannot use two separate CLI and MI channels — for example: because of lack of PTYs like on Windows or because GDB is used remotely via a SSH connection.

Result

The result consists of two or three fields:

‘completion’

This field contains the completed command. If command has no known completions, this field is omitted.

‘matches’

This field contains a (possibly empty) array of matches. It is always present.

‘max_completions_reached’

This field contains 1 if number of known completions is above max-completions limit (see Completion), otherwise it contains 0. It is always present.

GDB Command

The corresponding GDB command is ‘complete’.

Example

(gdb)
-complete br
^done,completion="break",
      matches=["break","break-range"],
      max_completions_reached="0"
(gdb)
-complete "b ma"
^done,completion="b ma",
      matches=["b madvise","b main"],max_completions_reached="0"
(gdb)
-complete "b push_b"
^done,completion="b push_back(",
      matches=[
       "b A::push_back(void*)",
       "b std::string::push_back(char)",
       "b std::vector<int, std::allocator<int> >::push_back(int&&)"],
      max_completions_reached="0"
(gdb)
-complete "nonexist"
^done,matches=[],max_completions_reached="0"
(gdb)

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