~/relaissrc$ gcc relais.c -g -o relais
relais.c: In function ‘init’:
relais.c:151: warning: incompatible implicit declaration of built-in function ‘exit’
relais.c: In function ‘getport’:
relais.c:180: warning: incompatible implicit declaration of built-in function ‘exit’
relais.c: In function ‘usage’:
relais.c:246: warning: incompatible implicit declaration of built-in function ‘exit’
relais.c: In function ‘main’:
relais.c:274: warning: incompatible implicit declaration of built-in function ‘exit’
relais.c:287: warning: incompatible implicit declaration of built-in function ‘exit’
relais.c:306: warning: incompatible implicit declaration of built-in function ‘exit’
relais.c:320: warning: incompatible implicit declaration of built-in function ‘exit’