[FIXED] How to create a TCP-IP named socket file in Unix?

Issue

I found out that, under 'everything is a file' philosophy in Unix, even sockets are considered as files, and can be stored in a path in file system. So, I was trying to create a TCP-IP socket file out of curiosity.

This answer shows how to create a named Unix domain socket file. But struct sockaddr_in doesn't have sin_path field. So I have no idea how to create a named TCP-IP socket file. Can anyone tell me how to do this?

Solution

... even sockets are considered as files, and can be stored in a path in file system.

Not really. There are some sockets where the endpoint is represented by a file. These are UNIX domain sockets (AF_UNIX) and their is a variant which has a message semantic (SOCK_DGRAM) similar to UDP and one which has a stream semantic (SOCK_STREAM) similar to TCP.

But, UDP and TCP sockets have a no file representation in UNIX. They have a file descriptor though similar to normal files (and read and write system calls work with these), but they are not represented by a path in the file system.

There is also something like /dev/tcp/.. to deal with sockets inside the bash shell. But this is not an actual path on the file system either, but only a fancy syntax specific to the bash shell.

For more on this see also Wikipedia: Everything is a file which specifically notes:

... Therefore, a more accurate description of this feature is Everything is a file descriptor.

Answered By - Steffen Ullrich

Answer Checked By - Dawn Plyler (PHPFixing Volunteer)