Links in Linux

Links help replicate a file to multiple location without creating redundant copies. The links point to the source file (as opposed to copying the file-contents). Any changes done to source file (after linking) are reflected in the links. Dangling links can be created to non-existent files.

There are 2 types of links: Hard links and Symbolic links.

Hard Links	Symbolic Links
Each hard link is a reference to the same i-node number (a key in the i-node table - inode entry for a file can be viewed using stat<<filename>>).	Each symbolic link contains the pathname of the source file.
Source cannot be a directory	Source can be a directory
Source & destination must be in the same file systems (because inode numbers are unique only within one file system)	Source and destination can reside anywhere

e.g.:
~/temp$ ls --inode source.txt # List file with inode number
2131296 source.txt

~/temp$ cp --link source.txt link-copied.txt # a hard link

~/temp$ cp --symbolic-link source.txt symbolic-link-copied.txt # a symbolic link

~/temp$ ls --inode source.txt link-copied.txt symbolic-link-copied.txt
2131296 link-copied.txt 
2131296 source.txt # hard link: i-node numbers of source and destination files are same
2133544 symbolic-link-copied.txt # symbolic link: i-node numbers differ