Hard Link

• Hard link is a directory entry that maps the file name with an inode in a file-system.
• A hard link creates a additional name for the same file, pointing at the same inode thus referring the same data.
• Hard links are indistinguishable from the original file even the timestamps will be the same(access time, modify time etc).
• Each file must have atleast one hard link because the hard link maps the file name with its inode which contains the metadata and pointers to the file content.
• Hard links can't be created between different file systems or partitions.

Creation of Hard links

touch hello.txt
ln hello.txt world.txt

• Here the world.txt is the hard link to hello.txt, they both are pointing to the same inode number thus the same data.
• Both files now contains the same data changes done to one will reflect in other file.
• Deleting one doesn't affect the other.