[renan@panic ~]:1033> cc -o hello hello.c
hello.c: In function ‘main’:
hello.c:5: warning: incompatible implicit declaration of built-in function ‘exit’
/usr/lib/gcc/i586-suse-linux/4.1.2/../../../../i586-suse-linux/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000008048290

[renan@panic ~]:1034> ./hello
Instrução ilegal