An exercise in minimalism.
Try the following:
gcc -o c4 c4.c (you may need the -m32 option on 64bit machines)
./c4 hello.c
./c4 -s hello.c
./c4 c4.c hello.c
./c4 c4.c c4.c hello.c
An exercise in bit-twiddling masochism.
x86 only, not self-hosted!
gcc -m32 c4x86.c -o c4x86
./c4x86 hello.c
./c4x86 c4.c hello.c