Debugging with GDB: Linespec Locations

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9.2.1 Linespec Locations

A linespec is a colon-separated list of source location parameters such as file name, function name, etc. Here are all the different ways of specifying a linespec:

linenum

Specifies the line number linenum of the current source file.

-offset

+offset

Specifies the line offset lines before or after the current line. For the list command, the current line is the last one printed; for the breakpoint commands, this is the line at which execution stopped in the currently selected stack frame (see Frames, for a description of stack frames.) When used as the second of the two linespecs in a list command, this specifies the line offset lines up or down from the first linespec.

filename:linenum

Specifies the line linenum in the source file filename. If filename is a relative file name, then it will match any source file name with the same trailing components. For example, if filename is ‘gcc/expr.c’, then it will match source file name of /build/trunk/gcc/expr.c, but not /build/trunk/libcpp/expr.c or /build/trunk/gcc/x-expr.c.

function

Specifies the line that begins the body of the function function. For example, in C, this is the line with the open brace.

By default, in C++ and Ada, function is interpreted as specifying all functions named function in all scopes. For C++, this means in all namespaces and classes. For Ada, this means in all packages.

For example, assuming a program with C++ symbols named A::B::func and B::func, both commands break func and break B::func set a breakpoint on both symbols.

Commands that accept a linespec let you override this with the -qualified option. For example, break -qualified func sets a breakpoint on a free-function named func ignoring any C++ class methods and namespace functions called func.

See Explicit Locations.

function:label

Specifies the line where label appears in function.

filename:function

Specifies the line that begins the body of the function function in the file filename. You only need the file name with a function name to avoid ambiguity when there are identically named functions in different source files.

label

Specifies the line at which the label named label appears in the function corresponding to the currently selected stack frame. If there is no current selected stack frame (for instance, if the inferior is not running), then GDB will not search for a label.

-pstap|-probe-stap [ objfile:[ provider:] ] name

The GNU/Linux tool SystemTap provides a way for applications to embed static probes. See Static Probe Points, for more information on finding and using static probes. This form of linespec specifies the location of such a static probe.

If objfile is given, only probes coming from that shared library or executable matching objfile as a regular expression are considered. If provider is given, then only probes from that provider are considered. If several probes match the spec, GDB will insert a breakpoint at each one of those probes.

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