$PROGRAM_NAME
$0      Contains the name of the program being executed.
        On some operating systems assigning to "$0" modi­
        fies the argument area that the ps program sees.
        This is more useful as a way of indicating the
        current program state than it is for hiding the
        program you're running.  (Mnemonic: same as sh and
        ksh.)

        Note for BSD users: setting "$0" does not com­
        pletely remove "perl" from the ps(1) output.  For
        example, setting "$0" to ""foobar"" will result in
        ""perl: foobar (perl)"".  This is an operating
        system feature.


##</code><code>##

# test3.pl
$0 = "bar" ;
while ( 1 ) { 1 } ;