Unix - Difference Between Hard Link and Soft Link in UNIX

Hard links and soft links are used in UNIX to create references to files without duplicating data. They help users manage files efficiently by allowing multiple access paths to the same file. Understanding the difference between hard and soft links is important for file management and system administration.

Hard Link
A hard link is an additional name for an existing file. Both the original file and the hard link point to the same data on the disk. If the original file is deleted, the data still exists as long as at least one hard link remains.

Soft Link (Symbolic Link)
A soft link is a special file that points to the path of another file. It acts like a shortcut. If the original file is deleted, the soft link becomes broken and cannot access the data anymore.

Inode Usage
Hard links share the same inode number, which means they directly reference the same file data. Soft links have a different inode and only store the file path, not the actual data.

File System Limitation
Hard links can be created only within the same file system and cannot link directories in most cases. Soft links can link files or directories across different file systems without restriction.

Behavior After File Deletion
When the original file is deleted, a hard link still works because it points to the same data. A soft link fails because it depends on the file path, which no longer exists.

Visibility and Identification
Hard links look exactly like normal files and are difficult to identify without checking inode numbers. Soft links are easily identified because they show a link arrow pointing to the target file.

Practical Command Example
The command ln file1 file2 creates a hard link, while ln -s file1 file2 creates a soft link. These commands are commonly used to manage file references efficiently.

Where It Is Used
Hard and soft links are widely used in UNIX systems for backup management, shared libraries, configuration files, and efficient storage handling.