Compilare: main.c: In function 'run': main.c:113:11: warning: unused variable 'op' [-Wunused-variable] char *s, op; ^~ main.c: In function 'main': main.c:171:6: warning: unused variable 'i' [-Wunused-variable] int i; ^ main.c:170:25: warning: unused variable 'stop' [-Wunused-variable] struct timespec start, stop; ^~~~ main.c:170:18: warning: unused variable 'start' [-Wunused-variable] struct timespec start, stop; ^~~~~ main.c: In function 'run': main.c:162:2: warning: ignoring return value of 'write', declared with attribute warn_unused_result [-Wunused-result] write(fd_out, output, oindex); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~