STACK(1) STACK(1)
NAME
stack, stackv - examine call stack
SYNOPSIS
bind '#p' /prog
stack [ -v ] [ -p dispath sblpath ]... pid
stackv [ -Tlm ] [ -r maxdepth ] [ pid[.sym] ...] ...
DESCRIPTION
Stack writes to the standard output a stack trace for pro-
cess 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 direc-
tories 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:
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STACK(1) STACK(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)
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