ben@Tyr:~$ alias foobar="/usr/bin/perl"
ben@Tyr:~$ cat <<! >xyz
> #!foobar -w
> print \$ARGV[0]
> !
ben@Tyr:~$ chmod +x xyz
ben@Tyr:~$ ./xyz Hello
-bash: ./xyz: foobar: bad interpreter: No such file or directory