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I understand file descriptors are kernel handle to identify the file , while inode number of a file is pointer to a structure which has other details about file(Correct me if I am wrong). But I am unable to get the difference between them.
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A file descriptor is a number that uniquely identifies an open file in a computer's operating system. It describes a data resource, and how that resource may be accessed. When a program asks to open a file — or another data resource, like a network socket — the kernel: Grants access.
From what I have gathered from Wikipedia, a file descriptor is an index in a file descriptor table, which points to a file name in a file table, which in turn points to an inode in an inode table. File handle is a type of data structure that stores a file descriptor.
An inode is denoted by the phrase "file serial number", defined as a per-file system unique identifier for a file. That file serial number, together with the device ID of the device containing the file, uniquely identify the file within the whole system.
An inode is an artifact of a particular file-system and how it manages indirection. A "traditional *ix" file-system uses this to link together files into directories, and even multiple parts of a file together. That is, an inode represents a physical manifestation of the file-system implementation.
On the other hand, a file descriptor is an opaque identifier to an open file by the Kernel. As long as the file remains open that identifier can be used to perform operations such as reading and writing. The usage of "file" here is not to be confused with a general "file on a disk" - rather a file in this context represents a stream and operations which can be performed upon it, regardless of the source.
A file descriptor is not related to an inode, except as such may be used internally by particular [file-system] driver.
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