In Unix-like operating systems, a device file or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. … These special files allow an application program to interact with a device by using its device driver via standard input/output system calls.
What is the use of special files in Unix?
Special Files – Used to represent a real physical device such as a printer, tape drive or terminal, used for Input/Output (I/O) operations. Device or special files are used for device Input/Output(I/O) on UNIX and Linux systems. They appear in a file system just like an ordinary file or a directory.
Which files are known as special files in Unix?
Explanation: There are two special files named /dev/null and /dev/tty which is used in UNIX for special purposes. For example, if we want to check whether the program runs successfully without seeing its output on the screen or may not want to save output in a file either.
What is character special files?
A character special file is a file that provides access to an input/output device. … Each character special file has a device major number, which identifies the device type, and a device minor number, which identifies a specific device of a given device type.
What are the 3 types of files in Unix?
The seven standard Unix file types are regular, directory, symbolic link, FIFO special, block special, character special, and socket as defined by POSIX. Different OS-specific implementations allow more types than what POSIX requires (e.g. Solaris doors).
What are the main features of Unix?
The UNIX operating system supports the following features and capabilities:
- Multitasking and multiuser.
- Programming interface.
- Use of files as abstractions of devices and other objects.
- Built-in networking (TCP/IP is standard)
- Persistent system service processes called “daemons” and managed by init or inet.
What file system does Unix use?
Directory Structure
Unix uses a hierarchical file system structure, much like an upside-down tree, with root (/) at the base of the file system and all other directories spreading from there. It has a root directory (/) that contains other files and directories.
What are the two types of device files?
There are two types of device files; character and block, as well as two modes of access. Block device files are used to access block device I/O.
How does Unix work?
The UNIX system is functionally organized at three levels: The kernel, which schedules tasks and manages storage; The shell, which connects and interprets users’ commands, calls programs from memory, and executes them; and. The tools and applications that offer additional functionality to the operating system.
Which is an example of character special file?
A character special file is similar to a block device, but data is written one character (eight bits, or one byte) at a time. Examples of character special files: /dev/stdin (Standard input.) /dev/stdout (Standard output.)
How many types of special files are there?
There are three basic types of special files: FIFO (first-in, first-out), block, and character. FIFO files are also called pipes.
What are block special files?
Block special files or block devices provide buffered access to hardware devices, and provide some abstraction from their specifics. Unlike character devices, block devices will always allow the programmer to read or write a block of any size (including single characters/bytes) and any alignment.