Understanding Linux Hard and Soft Links: Commands, Differences, and Limits

Introduction

In Windows, shortcuts are link files that become invalid when the target is removed. Linux uses links that are different: hard links and soft (symbolic) links.

Hard Links

Hard links are pointers to the original file's inode; they share the same inode and therefore the same file content.

Example:

[root@qll ~]# ll -i /etc/passwd
67544416 -rw-r--r--. 1 root root 882 Feb 5 11:50 /etc/passwd

Creating a hard link:

[root@qll ~]# ln /etc/passwd passwd_test
[root@qll ~]# ll -i /etc/passwd passwd_test
67544416 -rw-r--r--. 2 root root 882 Feb 5 11:50 /etc/passwd
67544416 -rw-r--r--. 2 root root 882 Feb 5 11:50 passwd_test

Both entries have the same inode number, indicating they refer to the same file. The first character in the permission field is "-", meaning a regular file; the link count column increases from 1 to 2.

Characteristics and Limitations of Hard Links

Consume almost no extra space because only a directory entry is added.

The file is not truly deleted until all hard links are removed.

Cannot be created across different file systems.

Cannot link directories.

Soft (Symbolic) Links

Soft links store the pathname of the target, so they can point to directories and cross file‑system boundaries. When the target is removed, the symbolic link becomes dangling, similar to Windows shortcuts.

Example with /etc/passwd:

[root@qll ~]# ln -s /etc/passwd passwd_soft
[root@qll ~]# ll -i /etc/passwd passwd_soft
67544416 -rw-r--r--. 1 root root 882 Feb 5 11:50 /etc/passwd
100663362 lrwxrwxrwx. 1 root root 11 Feb 19 17:51 passwd_soft -> /etc/passwd

The inode numbers differ, showing they are separate files.

The permission field shows "l", indicating a symbolic link.

The link count remains 1, so creating a soft link does not increase the target’s link count.

The size of the symbolic link file equals the length of the pathname (11 bytes).

The last column displays the target path.

ln Command

1. Hard Link

[root@qll tmp]# ln /tmp/data.txt data2.txt   # create hard link
[root@qll tmp]# rm -rf /tmp/data.txt        # delete source file
[root@qll tmp]# cat data2.txt               # still works because hard link remains

2. Soft Link

[root@qll tmp]# ln -s /tmp/te.txt /tmp/te2.txt   # create file soft link
[root@qll tmp]# ln -s /bin testbin                # create directory soft link
[root@qll tmp]# rm -rf /tmp/te.txt                # delete source file
[root@qll tmp]# cat /tmp/te2.txt                  # fails: No such file or directory