Master Linux File Links: Soft, Hard, and Symbolic Link Techniques

Introduction

This guide introduces what file links are in Linux and how to use them effectively.

Viewing Link Documentation

Running man ln shows the basic usage of creating links between files, while man link describes the link creation function.

Soft Link

A soft link (symbolic link) creates a new reference to a file; the new file’s inode points to the original file.

Hard Link

A hard link makes the old and new files share the same inode number.

Symbolic Link

In many Unix/Linux systems, symbolic links and soft links are treated the same, but the new file may point to a different inode depending on implementation.

Note: The terms “symbolic link” and “soft link” are often interchangeable, but you must know when to use each.

Creating Hard Links

shashi@linuxtechi ~}$ man ln<br/>ln  - make links between files

shashi@linuxtechi ~}$ ln<br/>ln: missing file operand<br/>Try 'ln --help' for more information.

shashi@linuxtechi ~}$ ls -la<br/>total 24<br/>drwx------ 4 root root 4096 Feb 6 15:23 .<br/>drwxr-xr-x 23 root root 4096 Jan 25 16:39 ..<br/>-rw-r--r-- 1 root root 3122 Jan 25 16:41 .bashrc<br/>drwx------ 2 root root 4096 Feb 6 15:23 .cache<br/>-rw-r--r-- 1 root root 0 Jan 25 16:41 .hushlogin<br/>-rw-r--r-- 1 root root 148 Aug 17 2015 .profile<br/>drwxr-xr-x 2 root root 4096 Jan 25 16:41 .ssh

shashi@linuxtechi ~}$ touch 123.txt<br/>shashi@linuxtechi ~}$ ls -l<br/>total 0<br/>-rw-r--r-- 1 root root 0 Feb 6 15:51 123.txt

shashi@linuxtechi ~}$ cat > 123.txt<br/>Welcome to this World!<br/>^C

shashi@linuxtechi ~}$ ln 123.txt 321.txt<br/>shashi@linuxtechi ~}$ ls -l<br/>total 8<br/>-rw-r--r-- 2 root root 23 Feb 6 15:52 123.txt<br/>-rw-r--r-- 2 root root 23 Feb 6 15:52 321.txt

shashi@linuxtechi ~}$ ls -li<br/>794583 -rw-r--r-- 2 root root 23 Feb 6 15:52 123.txt<br/>794583 -rw-r--r-- 2 root root 23 Feb 6 15:52 321.txt

shashi@linuxtechi ~}$ rm 123.txt<br/>shashi@linuxtechi ~}$ ls -l<br/>total 8<br/>-rw-r--r-- 2 root root 23 Feb 6 15:52 321.txt

shashi@linuxtechi ~}$ ls -li<br/>794583 -rw-r--r-- 2 root root 23 Feb 6 15:52 321.txt

Hard links cannot be created across directories.

shashi@linuxtechi ~}$ mkdir abc<br/>shashi@linuxtechi ~}$ ln abc def<br/>ln: abc: hard link not allowed for directory

Creating Soft (Symbolic) Links

shashi@linuxtechi ~}$ touch src.txt<br/>shashi@linuxtechi ~}$ cat > src.txt<br/>Hello World<br/>^C<br/>shashi@linuxtechi ~}$ ls -l<br/>total 4<br/>-rw-r--r-- 1 root root 12 Feb 6 16:32 src.txt

shashi@linuxtechi ~}$ ln -s src.txt dst.txt<br/>shashi@linuxtechi ~}$ ls -l<br/>total 4<br/>lrwxrwxrwx 1 root root 7 Feb 6 16:33 dst.txt -> src.txt<br/>-rw-r--r-- 1 root root 12 Feb 6 16:32 src.txt

shashi@linuxtechi ~}$ cat dst.txt<br/>Hello World

shashi@linuxtechi ~}$ ls -li<br/>794584 lrwxrwxrwx 1 root root 7 Feb 6 16:33 dst.txt -> src.txt<br/>794583 -rw-r--r-- 1 root root 12 Feb 6 16:32 src.txt

Symbolic links can also point to directories.

shashi@linuxtechi ~}$ mkdir abc<br/>shashi@linuxtechi ~}$ ln -s abc def<br/>shashi@linuxtechi ~}$ ls -l<br/>drwxr-xr-x 2 root root 4096 Feb 6 16:34 abc<br/>lrwxrwxrwx 1 root root 3 Feb 6 16:34 def -> abc

When the source directory receives new files, the linked target directory reflects the same changes.

shashi@linuxtechi ~}$ cd abc<br/>shashi@linuxtechi ~}$ touch 123.txt<br/>shashi@linuxtechi ~}$ vi 123.txt<br/>Hello<br/>:wq!<br/>shashi@linuxtechi ~}$ touch 456.txt<br/>shashi@linuxtechi ~}$ cd ..<br/>shashi@linuxtechi ~}$ ls -l<br/>drwxr-xr-x 2 root root 4096 Feb 6 16:36 abc<br/>lrwxrwxrwx 1 root root 3 Feb 6 16:34 def -> abc

shashi@linuxtechi ~}$ cd def<br/>shashi@linuxtechi ~}$ ls -l<br/>-rw-r--r-- 1 root root 6 Feb 6 16:37 123.txt<br/>-rw-r--r-- 1 root root 0 Feb 6 16:36 456.txt<br/>shashi@linuxtechi ~}$ cat 123.txt<br/>Hello

Removing Soft Links

Use rm or unlink to delete a symbolic link or its directory.

# rm <soft-link-filename><br># unlink <soft-link-filename>

# rm <soft-link-directory><br># unlink <soft-link-directory>

Source: 鸠摩智首席音效师