use OpaL::where qw(which);
DESCRIPTIONOpaL::where is a module for locating system resources.
Which takes a program name and searches for that in the PATH environment
variable and returns the path to the executable. If no program is found with
that name undef is returned instead.
This is similar to the program with the same name. See which(1).
$t = "which"(``perl'');