What is the difference between anonymous and named pipe?

The Difference Between Anonymous and Named Pipes

Pipes are a fundamental concept in the Linux operating system, providing a way for processes to communicate with each other by passing data from the output of one process to the input of another. There are two main types of pipes in Linux: anonymous pipes and named pipes.

Anonymous Pipes

An anonymous pipe is a temporary, one-way communication channel that is created and used within a single process or between related processes. It is created using the pipe() system call and is identified by a file descriptor, which is a small integer that represents an open file in the operating system.

Here's an example of how to create an anonymous pipe in a C program:

int fd[2];
if (pipe(fd) == -1) {
    perror("pipe");
    return 1;
}

In this example, fd[0] represents the read end of the pipe, and fd[1] represents the write end of the pipe. The processes can then use these file descriptors to read and write data to the pipe.

Anonymous pipes are commonly used for inter-process communication (IPC) within a single application or between related processes, such as a parent and child process. They are simple to use and provide a way to pass data between processes without the need for additional setup or configuration.

However, anonymous pipes have some limitations:

• They are one-way communication channels, meaning data can only flow in one direction.
• They are temporary and exist only for the lifetime of the processes that created them.
• They can only be used between related processes, such as a parent and child process.

Named Pipes

A named pipe, also known as a FIFO (First-In, First-Out), is a special type of file that acts as a communication channel between unrelated processes. Unlike anonymous pipes, named pipes have a persistent file system representation and can be accessed by any process that has the appropriate permissions.

Here's an example of how to create a named pipe in a Linux terminal:

mkfifo my_pipe

This creates a named pipe file called my_pipe in the current directory. Any process can then open this file for reading or writing, and the data will be passed between the processes in a first-in, first-out manner.

Here's an example of how to use a named pipe in a C program:

int fd = open("my_pipe", O_RDWR);
if (fd == -1) {
    perror("open");
    return 1;
}

Named pipes have several advantages over anonymous pipes:

• They can be used for communication between unrelated processes, not just parent-child processes.
• They have a persistent file system representation, so they can be used for long-term communication between processes.
• They can be used for bi-directional communication, as both ends of the pipe can be opened for reading and writing.

However, named pipes also have some limitations:

• They require explicit creation and setup, which can be more complex than anonymous pipes.
• They can only be used for communication within a single system, not across a network.

In summary, the main differences between anonymous and named pipes are:

• Persistence: Anonymous pipes are temporary and exist only for the lifetime of the processes that created them, while named pipes have a persistent file system representation.
• Directionality: Anonymous pipes are one-way communication channels, while named pipes can be used for bi-directional communication.
• Relationship: Anonymous pipes can only be used between related processes, while named pipes can be used for communication between unrelated processes.
• Setup: Creating an anonymous pipe is simpler than creating a named pipe, which requires explicit creation and setup.

The choice between using an anonymous or named pipe depends on the specific requirements of the application and the communication needs between the processes.