`'''[http://www.tcl.tk/man/tcl/TclCmd/tclvars.htm#M39%|%tcl_traceExec]'''`, a
[tclvars%|%built-in] [Tcl] variable, controls how much tracing information is
displayed during bytecode execution.


** See Also **

   [bytecode]:   



** Description **

By default, the value of `$tcl_traceExec` is `0`, and no information is
displayed.  Setting  `$tcl_traceExec` to `1` generates a one-line trace in
stdout on each call to a Tcl procedure.  Setting it to `2` generates a line of
output whenever any Tcl command is invoked that contains the name of the
command and its arguments.  Setting it to 3 produces a detailed trace showing
the result of executing each bytecode instruction.  Note that when
`$tcl_traceExec` is `2` or `3`, commands such as `[set]` and `[incr]` that have
been entirely replaced by a sequence of bytecode instructions are not shown.
Setting this variable is useful in tracking down suspected problems with the
bytecode compiler and interpreter.

`$tcl_traceExec` and its functionality only exist if `TCL_COMPILE_DEBUG` was
defined when Tcl was compiled. This is usually done by passing `--enable-symbols=all` to `configure` during the build of Tcl.



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