Block device and character device

Question

Describe block device and character device?

Answer 1

Character devices deal along with IO on a character through character basis. The clearest example is a keyboard, where every key produce a character on the device. The mouse is another instance of character devices. Every motion or click sends a character to the /dev/input/mouse0 device. To check it out do $cat /dev/input/mouse0 , then move mouse (see what happens)

Block devices read data in big chunks or blocks. Data storage devices, like IDE hard drives (/dev/hd), SCSI hard drives (/dev/sd), and CD-ROMs (/dev/cdrom or /dev/sr0) are block devices. IO interactions along with block devices transact to chunks of data (blocks), which let large quantities of data to be moved back and forth more efficiently(unlike character device). eg: $df -h

Broadly, block devices can be mounted and cached, and char devices are for communication devices, aren’t cached nor block aligned, and can’t be mounted. Particularly, /dev/scd* (block) are for cdroms, provide the block access and commands for ejecting, closing, playing, etc. The equivalent character device for the cdrom is /dev/sg1