Microsoft Windows [Version 6.0.6001]
Copyright (c) 2006 Microsoft Corporation.  All rights reserved.

c:\>cd test

c:\test>set pathext
PATHEXT=.pl;.COM;.EXE;.BAT;.CMD;

c:\test>junk junk.pl
'print "'$_'" while <>;
'
c:\test>junk < junk.pl
'print "'$_'" while <>;
'
c:\test>type junk.pl | junk
'print "'$_'" while <>;
'
c:\test>set pathext=.com;.exe;.bat;.cmd;

c:\test>set pathext
PATHEXT=.com;.exe;.bat;.cmd;

c:\test>junk junk.pl
'junk' is not recognized as an internal or external command,
operable program or batch file.

c:\test>junk < junk.pl
'junk' is not recognized as an internal or external command,
operable program or batch file.

c:\test>type junk.pl | junk
'junk' is not recognized as an internal or external command,
operable program or batch file.

c:\test>set pathexe=%pathext%.pl;

c:\test>set pathext
PATHEXT=.com;.exe;.bat;.cmd;

c:\test>set pathext=%pathext%.pl;

c:\test>set pathext
PATHEXT=.com;.exe;.bat;.cmd;.pl;

c:\test>junk junk.pl
'print "'$_'" while <>;
'
c:\test>junk < junk.pl
'print "'$_'" while <>;
'
c:\test>type junk.pl | junk
'print "'$_'" while <>;
'
c:\test>