How do I open a character device in Linux?

In Linux, to get a character device for a disk, one must use the “raw” driver, though one can get the same effect as opening a character device by opening the block device with the Linux-specific O_DIRECT flag.

What is character device driver in Linux?

Character device drivers normally perform I/O in a byte stream. Examples of devices using character drivers include tape drives and serial ports. Character device drivers can also provide additional interfaces not present in block drivers, such as I/O control (ioctl) commands, memory mapping, and device polling.