Most of the data that is displayed by the free and vmstat commands actually comes from the /proc/dma O /proc/interrupts /proc/meminfo /proc/cpuinfo file, which can be viewed directly. To view the USB devices available on the system, one could Isdev cat /proc/ioports Isusb Isblk The job of the spooler printer Olpr Olpd is to control access to the printer so that one print job finishes before the next one starts.