= stack, stackv: examine call stack


*bind '#p' /prog* +
*stack* [ *-v* ] [ *-p* _dispath_ _sblpath_ ]... _pid_ +
*stackv* [ *-Tlm* ] [ *-r* _maxdepth_ ] [ _pid[._sym_] ...] ..._


_Stack_ writes to the standard output a stack trace for process _pid_,
by decoding the stack traceback data contained in the file
**/prog/**__pid__**/stack**__.__ The *-v* option causes _stack_ to print
values of arguments and variables. The output is most useful when the
Limbo program was compiled with the *-g* option to produce a *.sbl*
symbol file.

_Stack_ has a built-in list of associations between *dis* directories
and their associated source directories (e.g. it can automatically map
from */dis/ls.dis* to */appl/cmd/ls.sbl*). Giving the *-p* option adds a
new association to the head of this list: if a module path prefix
matches _dispath_, _stack_ will search for a symbol file in _sblpath_.
If the environment variable *$sblpath* is set, pairs of items from it
are added to the association list, as given as *-p* options. The *-p*
options take precedence over *$sblpath*.

_Stackv_ recursively traverses the symbols it finds, printing values as
it goes. Repeated identical structure is not shown - only the pointer
value is printed, followed by *(qv)*. Each argument gives a starting
point for the traversal, rooted by a process id, _pid_. If an unadorned
process id is given, all values in all stack frames in the process will
be printed; adding names specifies the starting point. For instance,
*123.init.ctxt.display* might specify the *display* field inside the
*ctxt* adt inside the *init* function inside the process *123*. _Stackv_
understands the following options:

*-l*::
  Show source line information with each item.
*-m*::
  Show module variables accessible from each stack frame.
*-T*::
  Do not show the Limbo types of value encountered.
**-r**__ maxdepth__::
  Restrict the maximum traversal depth to _maxdepth_ levels.

== EXAMPLE

Run _stack_ on process with ID 1:

....
$ stack 1
unknown fn() Module $Sys PC 742103
waitfor() shnew.b:105.7, 38
runpipeline() shnew.b:483.2, 14
runit() shnew.b:552.3, 29
init() shnew.b:83.3, 28
....

The process is executing in the *Sys* module, a call to *sys->read* that
originated at line 105 (characters 7 to 38) of the *waitfor* function in
*shnew.b*.

Once again, with the *-v* option to reveal more:

....
$ stack -v 1
unknown fn() Module $Sys PC 742103
waitfor(pid=18) shnew.b:105.7, 38
        status=[0] ""
        buf=[64] @b419a4
        n=-1
        who=-1
runpipeline(ctx=nil, pipeline=@b41454) shnew.b:483.2, 14
        pid=18
runit(ctx=nil, pipes=nil) shnew.b:552.3, 29
        pipeline=@b41454
init(ctxt=nil, argv=nil) shnew.b:83.3, 28
        buf=[1024] @b40f04
        n=4
        arg=@b41634
        prompt=[21] "$ "
$
....

== FILES

**/prog/**__pid__*/stack* +
**/prog/**__pid__*/status*

== SOURCE

*/appl/cmd/stack.b* +
*/appl/cmd/stackv.b*

== SEE ALSO

_deb_(1), _ps_(1), _prog_(3), _debug_(2)