Call a Mathematica program from the command line, with command-line args, stdin, stdout, and stderr

#!/usr/bin/env MathKernel
x = 2+2;
Print[x];
Print["There were ", Length[ARGV], " args passed in on the command line."];
linesFromStdin = readList[];
etc.

#!/bin/sh
exec <"$0" || exit; read; read; exec /usr/local/bin/math -noprompt "$@" | sed '/^$/d'; exit
(* Mathematica code starts here *)
x = 2+2;
Print[x];

export PATH=$PATH:/Applications/Mathematica.app/Contents/MacOS

#!/usr/bin/env MathKernel -script

$ cat hello.ma
#!/usr/bin/env MathKernel -script

Print["Hello World!"]

$ chmod a+x hello.ma
$ ./hello.ma
"Hello World!"