[SOLVED] UNIX: Is the i-number same as the file descriptor?

Issue

Dennis Ritchie and Ken Thompson's paper UNIX Time-Sharing System mentions the following points

1. About i-number: A directory entry contains only a name for the associated file and a pointer to the file itself. This pointer is an integer called the i-number (for index number) of the file
2. About open and create system-calls: The returned value (of open and create) is called a file descriptor. It is a small integer used to identify the file in subsequent calls
3. Purpose of open/create: The purpose of an open or create system call is to turn the path name given by the user into an i-number by searching the explicitly or implicitly named directories

Does this mean that the file descriptor is just the i-number of a file? Or am I missing something?

Solution

A file descriptor in UNIX is basically just an index into the array of open files for the current process.

An inode number is an index into the inode table for the file system.

So they're basically just integers, indexes into an array, but they are indexes into completely different, unrelated arrays. So there is no connection between them.

Answered By - Chris Dodd

Answer Checked By - Marilyn (WPSolving Volunteer)