NAME

SYNOPSIS

DESCRIPTION

The first line of the output displays the pid of the traced process, binary name as reported by the kernel, and the currently active osrel version of the ABI for the process. After that, for each thread in the process, the thread id is displayed, followed by the backtrace.

The following options are available:

-a count

Try to guess the arguments of each function appearing in the backtrace. Not more than count arguments are printed for each function. Ability to correctly read the argument values depends on the architecture and compiler optimization, but it is generally impossible to do.

-f count

For each thread, print not more than count frames in the backtrace.

-l

Instead of walking the stacks of the running threads, print the names of the shared objects loaded into the process address space. The output of the utility resembles the output of ldd(1) command run on the binary.

-o

Show the names of the objects which contain the location of the frame current instruction pointer.

-O

Same as -o, but displays the full path to the objects instead of only names.

-t

Measure and print the time which the target process was suspended to walk the stack frames.

-v

Be verbose.

SEE ALSO

AUTHORS

CAVEATS

On amd64, the argument printing currently does not work. The amd64 ABI specifies that integer arguments are passed in the registers which are not required to be preserved across function calls. As the result, there is typically no way to re-create the arguments values on any frame except the current one.

The symbol names cannot be inferred if the corresponding binary or shared object are already deleted, since libunwind needs to read the symbols from the on-disk ELF image. This could typically occur if the binary or library is reinstalled, but the process uses older version of the binary with the same name.

The pstack only works on the processes executing ELF binaries.

You cannot get a backtrace for the process, to which another debugger is currently attached. The ptrace(2) debugging mechanism used to obtain the neccessary live process information causes some syscalls to return EINTR errors on pstack detach.

The pstack utility cannot yet extract a backtrace from the core dump.

The architecture of the program and pstack shall match (this is libunwind restriction).