$output = system('ls -l'); echo $output;
if (!file_exists('mydir')) { mkdir('mydir'); }
echo 'CPU cores: ' . sysconf(_SC_NPROCESSORS_ONLN); echo 'Memory: ' . memory_get_usage();These functions print the number of CPU cores and the amount of memory being used by the PHP script. Overall, the PHP System library provides a convenient way to interact with the system on which the PHP application is running.