File::Which was created to be able to get the paths to executable programs on
systems under which the `which' program wasn't implemented in the shell.

File::Which searches the directories of the user's PATH (as returned by
File::Spec->path()), looking for executable files having the name specified as
a parameter to which(). Under Win32 systems, which do not have a notion of
directly executable files, but uses special extensions such as .exe and .bat to
identify them, File::Which takes extra steps to assure that you will find the
correct file (so for example, you might be searching for perl, it'll try
perl.exe, perl.bat, etc.)

These slurp/spew subs work for files, pipes and sockets, and stdio,
pseudo-files, and DATA.