Unix Administrator Interview Question: Difference between Hard Link and Soft Link

In Unix/Linux, both hard links and soft links are used to create a reference to a file. However, there are key differences between the two:

Hard Link:

A hard link is an exact copy of the original file's inode, essentially creating a new name for the same data on disk. Changes to one hard link of a file will affect all other hard links as they are essentially the same file. Hard links cannot cross filesystem boundaries.

Soft Link (Symbolic Link):

A soft link, also known as a symbolic link, is a pointer to the original file's pathname. It is a separate file that references the original file's inode number. Soft links can span filesystems and can link to directories as well as files. If the original file is deleted, the soft link becomes a "dangling link" that points to nothing.

When to use Each:

Use hard links when you want multiple file names to point to the same data on disk and when you need changes made to one file to reflect in all linked files. Hard links are commonly used for critical system files that should always be accessible and never be deleted accidentally.

Use soft links when you need a shortcut to access a file or directory, or when working across filesystem boundaries. Soft links are commonly used for creating symbolic references to important directories or files to simplify navigation.