GDB/MI Breakpoint Commands (Debugging with GDB)

Next: GDB/MI Catchpoint Commands, Previous: GDB/MI Command Description Format, Up: GDB/MI [Contents][Index]

### 27.8 GDB/MI Breakpoint Commands

This section documents GDB/MI commands for manipulating breakpoints.

#### The `-break-after` Command

#### Synopsis

     -break-after number count

The breakpoint number number is not in effect until it has been hit count times. To see how this is reflected in the output of the ‘`-break-list`’ command, see the description of the ‘`-break-list`’ command below.

#### GDB Command

The corresponding GDB command is ‘`ignore`’.

#### Example

    (gdb)
    -break-insert main
    ^done,bkpt={number="1",type="breakpoint",disp="keep",
    enabled="y",addr="0x000100d0",func="main",file="hello.c",
    fullname="/home/foo/hello.c",line="5",thread-groups=["i1"],
    times="0"}
    (gdb)
    -break-after 1 3
    ~
    ^done
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="1",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
    line="5",thread-groups=["i1"],times="0",ignore="3"}]}
    (gdb)

#### The `-break-commands` Command

#### Synopsis

     -break-commands number [ command1 ... commandN ]

Specifies the CLI commands that should be executed when breakpoint number is hit. The parameters command1 to commandN are the commands. If no command is specified, any previously-set commands are cleared. See Break Commands. Typical use of this functionality is tracing a program, that is, printing of values of some variables whenever breakpoint is hit and then continuing.

#### GDB Command

The corresponding GDB command is ‘`commands`’.

#### Example

    (gdb)
    -break-insert main
    ^done,bkpt={number="1",type="breakpoint",disp="keep",
    enabled="y",addr="0x000100d0",func="main",file="hello.c",
    fullname="/home/foo/hello.c",line="5",thread-groups=["i1"],
    times="0"}
    (gdb)
    -break-commands 1 "print v" "continue"
    ^done
    (gdb)

#### The `-break-condition` Command

#### Synopsis

     -break-condition [ --force ] number [ expr ]

Breakpoint number will stop the program only if the condition in expr is true. The condition becomes part of the ‘`-break-list`’ output (see the description of the ‘`-break-list`’ command below). If the ‘`--force`’ flag is passed, the condition is forcibly defined even when it is invalid for all locations of breakpoint number. If the expr argument is omitted, breakpoint number becomes unconditional.

#### GDB Command

The corresponding GDB command is ‘`condition`’.

#### Example

    (gdb)
    -break-condition 1 1
    ^done
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="1",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
    line="5",cond="1",thread-groups=["i1"],times="0",ignore="3"}]}
    (gdb)

#### The `-break-delete` Command

#### Synopsis

     -break-delete ( breakpoint )+

Delete the breakpoint(s) whose number(s) are specified in the argument list. This is obviously reflected in the breakpoint list.

#### GDB Command

The corresponding GDB command is ‘`delete`’.

#### Example

    (gdb)
    -break-delete 1
    ^done
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="0",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[]}
    (gdb)

#### The `-break-disable` Command

#### Synopsis

     -break-disable ( breakpoint )+

Disable the named breakpoint(s). The field ‘`enabled`’ in the break list is now set to ‘`n`’ for the named breakpoint(s).

#### GDB Command

The corresponding GDB command is ‘`disable`’.

#### Example

    (gdb)
    -break-disable 2
    ^done
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="1",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="n",
    addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
    line="5",thread-groups=["i1"],times="0"}]}
    (gdb)

#### The `-break-enable` Command

#### Synopsis

     -break-enable ( breakpoint )+

Enable (previously disabled) breakpoint(s).

#### GDB Command

The corresponding GDB command is ‘`enable`’.

#### Example

    (gdb)
    -break-enable 2
    ^done
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="1",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
    addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
    line="5",thread-groups=["i1"],times="0"}]}
    (gdb)

#### The `-break-info` Command

#### Synopsis

     -break-info breakpoint

Get information about a single breakpoint.

The result is a table of breakpoints. See GDB/MI Breakpoint Information, for details on the format of each breakpoint in the table.

#### GDB Command

The corresponding GDB command is ‘`info break breakpoint`’.

#### Example

N.A.

#### The `-break-insert` Command

#### Synopsis

     -break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ] [ --qualified ]
        [ -c condition ] [ --force-condition ] [ -i ignore-count ]
        [ -p thread-id ] [ -g thread-group-id ] [ locspec ]

If specified, locspec, can be one of:

linespec location

  A linespec location. See Linespec Locations.

explicit location

  An explicit location. GDB/MI explicit locations are analogous to the CLI’s explicit locations using the option names listed below. See Explicit Locations.

  ‘`--source filename`’

    The source file name of the location. This option requires the use of either ‘`--function`’ or ‘`--line`’.

  ‘`--function function`’

    The name of a function or method.

  ‘`--label label`’

    The name of a label.

  ‘`--line lineoffset`’

    An absolute or relative line offset from the start of the location.

address location

  An address location, *address. See Address Locations.

The possible optional parameters of this command are:

‘`-t`’

  Insert a temporary breakpoint.

‘`-h`’

  Insert a hardware breakpoint.

‘`-f`’

  If locspec cannot be resolved (for example if it refers to unknown files or functions), create a pending breakpoint. Without this flag, GDB will report an error, and won’t create a breakpoint, if locspec cannot be parsed.

‘`-d`’

  Create a disabled breakpoint.

‘`-a`’

  Create a tracepoint. See Tracepoints. When this parameter is used together with ‘`-h`’, a fast tracepoint is created.

‘`-c condition`’

  Make the breakpoint conditional on condition.

‘`--force-condition`’

  Forcibly define the breakpoint even if the condition is invalid at all of the breakpoint locations.

‘`-i ignore-count`’

  Initialize the ignore-count.

‘`-p thread-id`’

  Restrict the breakpoint to the thread with the specified global thread-id. thread-id must be a valid thread-id at the time the breakpoint is requested. Breakpoints created with a thread-id will automatically be deleted when the corresponding thread exits.

‘`-g thread-group-id`’

  Restrict the breakpoint to the thread group with the specified thread-group-id.

‘`--qualified`’

  This option makes GDB interpret a function name specified as a complete fully-qualified name.

#### Result

See GDB/MI Breakpoint Information, for details on the format of the resulting breakpoint.

Note: this format is open to change.

#### GDB Command

The corresponding GDB commands are ‘`break`’, ‘`tbreak`’, ‘`hbreak`’, and ‘`thbreak`’.

#### Example

    (gdb)
    -break-insert main
    ^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",
    fullname="/home/foo/recursive2.c,line="4",thread-groups=["i1"],
    times="0"}
    (gdb)
    -break-insert -t foo
    ^done,bkpt={number="2",addr="0x00010774",file="recursive2.c",
    fullname="/home/foo/recursive2.c,line="11",thread-groups=["i1"],
    times="0"}
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="2",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x0001072c", func="main",file="recursive2.c",
    fullname="/home/foo/recursive2.c,"line="4",thread-groups=["i1"],
    times="0"},
    bkpt={number="2",type="breakpoint",disp="del",enabled="y",
    addr="0x00010774",func="foo",file="recursive2.c",
    fullname="/home/foo/recursive2.c",line="11",thread-groups=["i1"],
    times="0"}]}
    (gdb)

#### The `-dprintf-insert` Command

#### Synopsis

     -dprintf-insert [ -t ] [ -f ] [ -d ] [ --qualified ]
        [ -c condition ] [--force-condition] [ -i ignore-count ]
        [ -p thread-id ] [ locspec ] format
        [ argument… ]

Insert a new dynamic print breakpoint at the given location. See Dynamic Printf. format is the format to use, and any remaining arguments are passed as expressions to substitute.

If supplied, locspec and `--qualified` may be specified the same way as for the `-break-insert` command. See -break-insert.

The possible optional parameters of this command are:

‘`-t`’

  Insert a temporary breakpoint.

‘`-f`’

  If locspec cannot be parsed (for example, if it refers to unknown files or functions), create a pending breakpoint. Without this flag, GDB will report an error, and won’t create a breakpoint, if locspec cannot be parsed.

‘`-d`’

  Create a disabled breakpoint.

‘`-c condition`’

  Make the breakpoint conditional on condition.

‘`--force-condition`’

  Forcibly define the breakpoint even if the condition is invalid at all of the breakpoint locations.

‘`-i ignore-count`’

  Set the ignore count of the breakpoint (see ignore count) to ignore-count.

‘`-p thread-id`’

  Restrict the breakpoint to the thread with the specified global thread-id.

#### Result

See GDB/MI Breakpoint Information, for details on the format of the resulting breakpoint.

#### GDB Command

The corresponding GDB command is ‘`dprintf`’.

#### Example

    (gdb)
    4-dprintf-insert foo "At foo entry\n"
    4^done,bkpt={number="1",type="dprintf",disp="keep",enabled="y",
    addr="0x000000000040061b",func="foo",file="mi-dprintf.c",
    fullname="mi-dprintf.c",line="25",thread-groups=["i1"],
    times="0",script=["printf \"At foo entry\\n\"","continue"],
    original-location="foo"}
    (gdb)
    5-dprintf-insert 26 "arg=%d, g=%d\n" arg g
    5^done,bkpt={number="2",type="dprintf",disp="keep",enabled="y",
    addr="0x000000000040062a",func="foo",file="mi-dprintf.c",
    fullname="mi-dprintf.c",line="26",thread-groups=["i1"],
    times="0",script=["printf \"arg=%d, g=%d\\n\", arg, g","continue"],
    original-location="mi-dprintf.c:26"}
    (gdb)

#### The `-break-list` Command

#### Synopsis

     -break-list

Displays the list of inserted breakpoints, showing the following fields:

‘`Number`’

  number of the breakpoint

‘`Type`’

  type of the breakpoint: ‘`breakpoint`’ or ‘`watchpoint`’

‘`Disposition`’

  should the breakpoint be deleted or disabled when it is hit: ‘`keep`’ or ‘`nokeep`’

‘`Enabled`’

  is the breakpoint enabled or no: ‘`y`’ or ‘`n`’

‘`Address`’

  memory location at which the breakpoint is set

‘`What`’

  logical location of the breakpoint, expressed by function name, file name, line number

‘`Thread-groups`’

  list of thread groups to which this breakpoint applies

‘`Times`’

  number of times the breakpoint has been hit

If there are no breakpoints, watchpoints, tracepoints, or catchpoints, the `BreakpointTable` `body` field is an empty list.

#### GDB Command

The corresponding GDB command is ‘`info break`’.

#### Example

    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="2",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x000100d0",func="main",file="hello.c",line="5",thread-groups=["i1"],
    times="0"},
    bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
    addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c",
    line="13",thread-groups=["i1"],times="0"}]}
    (gdb)

Here’s an example of the result when there are no breakpoints:

    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="0",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[]}
    (gdb)

#### The `-break-passcount` Command

#### Synopsis

     -break-passcount tracepoint-number passcount

Set the passcount for tracepoint tracepoint-number to passcount. If the breakpoint referred to by tracepoint-number is not a tracepoint, error is emitted. This corresponds to CLI command ‘`passcount`’.

#### The `-break-watch` Command

#### Synopsis

     -break-watch [ -a | -r ]

Create a watchpoint. With the ‘`-a`’ option it will create an access watchpoint, i.e., a watchpoint that triggers either on a read from or on a write to the memory location. With the ‘`-r`’ option, the watchpoint created is a read watchpoint, i.e., it will trigger only when the memory location is accessed for reading. Without either of the options, the watchpoint created is a regular watchpoint, i.e., it will trigger when the memory location is accessed for writing. See Setting Watchpoints.

Note that ‘`-break-list`’ will report a single list of watchpoints and breakpoints inserted.

#### GDB Command

The corresponding GDB commands are ‘`watch`’, ‘`awatch`’, and ‘`rwatch`’.

#### Example

Setting a watchpoint on a variable in the `main` function:

    (gdb)
    -break-watch x
    ^done,wpt={number="2",exp="x"}
    (gdb)
    -exec-continue
    ^running
    (gdb)
    *stopped,reason="watchpoint-trigger",wpt={number="2",exp="x"},
    value={old="-268439212",new="55"},
    frame={func="main",args=[],file="recursive2.c",
    fullname="/home/foo/bar/recursive2.c",line="5",arch="i386:x86_64"}
    (gdb)

Setting a watchpoint on a variable local to a function. GDB will stop the program execution twice: first for the variable changing value, then for the watchpoint going out of scope.

    (gdb)
    -break-watch C
    ^done,wpt={number="5",exp="C"}
    (gdb)
    -exec-continue
    ^running
    (gdb)
    *stopped,reason="watchpoint-trigger",
    wpt={number="5",exp="C"},value={old="-276895068",new="3"},
    frame={func="callee4",args=[],
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13",
    arch="i386:x86_64"}
    (gdb)
    -exec-continue
    ^running
    (gdb)
    *stopped,reason="watchpoint-scope",wpnum="5",
    frame={func="callee3",args=[{name="strarg",
    value="0x11940 \"A string argument.\""}],
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18",
    arch="i386:x86_64"}
    (gdb)

Listing breakpoints and watchpoints, at different points in the program execution. Note that once the watchpoint goes out of scope, it is deleted.

    (gdb)
    -break-watch C
    ^done,wpt={number="2",exp="C"}
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="2",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x00010734",func="callee4",
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",thread-groups=["i1"],
    times="1"},
    bkpt={number="2",type="watchpoint",disp="keep",
    enabled="y",addr="",what="C",thread-groups=["i1"],times="0"}]}
    (gdb)
    -exec-continue
    ^running
    (gdb)
    *stopped,reason="watchpoint-trigger",wpt={number="2",exp="C"},
    value={old="-276895068",new="3"},
    frame={func="callee4",args=[],
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13",
    arch="i386:x86_64"}
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="2",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x00010734",func="callee4",
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",thread-groups=["i1"],
    times="1"},
    bkpt={number="2",type="watchpoint",disp="keep",
    enabled="y",addr="",what="C",thread-groups=["i1"],times="-5"}]}
    (gdb)
    -exec-continue
    ^running
    ^done,reason="watchpoint-scope",wpnum="2",
    frame={func="callee3",args=[{name="strarg",
    value="0x11940 \"A string argument.\""}],
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18",
    arch="i386:x86_64"}
    (gdb)
    -break-list
    ^done,BreakpointTable={nr_rows="1",nr_cols="6",
    hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
    {width="14",alignment="-1",col_name="type",colhdr="Type"},
    {width="4",alignment="-1",col_name="disp",colhdr="Disp"},
    {width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
    {width="10",alignment="-1",col_name="addr",colhdr="Address"},
    {width="40",alignment="2",col_name="what",colhdr="What"}],
    body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
    addr="0x00010734",func="callee4",
    file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
    fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
    thread-groups=["i1"],times="1"}]}
    (gdb)

Next: GDB/MI Catchpoint Commands, Previous: GDB/MI Command Description Format, Up: GDB/MI [Contents][Index]