Surely parameterless shift and pop, operate on @ARGV in the main, or @_ in a sub, as described. But unshift and push, unseasoned with parameters, are a syntax error.

/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;print join 
+"<>", @ARGV;'
that<>more
/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;push;print 
+join "<>", @ARGV;'
Not enough arguments for push at -e line 1, near "push;"
/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;unshift;pri
+nt join "<>", @ARGV;'
Not enough arguments for unshift at -e line 1, near "unshift;"
/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;push "X";pr
+int join "<>", @ARGV;'
Type of arg 1 to push must be array (not constant item) at -e line 1, 
+near ""X";"
 /usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;unshift "X
+";print join "<>", @ARGV;'
Type of arg 1 to unshift must be array (not constant item) at -e line 
+1, near ""X";"
[download]

Or is there a cunning way to make them dance?

Cheers,
R.