What information is modified when a hard link is created for an existing file?

When a hard link is created for an existing file, the main aspect that is affected is the link count. Each hard link essentially points to the same inode of the file, which means that the file’s data on the disk is not duplicated. Instead, the link count, which represents the number of directory entries that reference the inode, is incremented.

This is significant because it allows multiple directory entries to refer to the same file content without creating additional copies of the actual data. Therefore, if you delete one hard link, the file data remains accessible via other links until the link count reaches zero, at which point the inode and the associated data on the disk are freed.

In contrast to the link count, the file name, permissions, and size remain unchanged upon the creation of a hard link. The file name changes only in the context of creating a new directory entry that links to the existing file, while file permissions and file size are inherent properties of the original file and are not affected by the creation of additional links.