Linking to Files in Linux

Introduction

File linking in Linux is a powerful feature that allows users to create multiple references to the same file. This can be useful in a variety of situations, such as when you want to link to a file or when you want to share a file across multiple directories. In this article we will discuss the different types of shortcuts that can be created in Linux and the commands used to create them. We'll also explore the differences between hard links and soft links, and when to use each type.

Hard Links

A hard link is a direct link to the physical file on the file system. When a hard link is created, it is treated as a separate file, but is actually just a reference to the original file. This means that any changes made to the original file will also be reflected in the hard link and vice versa. A hard link is essentially another name for the same file and shares the same inode number as the original file.

Creating a Hard Link

Creating a hard link is done using the ln command. The basic syntax is as follows −

$ ln original_file hard_link

For example, if we have a file called “original.txt” and we want to create a hard link called “link.txt”, we would use the following command −

$ ln original.txt link.txt 
ln: failed to create hard link 'link.txt' => 'original.txt': Operation not permitted

It is important to note that creating hard links requires root access, and furthermore, it is not possible to create a hard link for a directory.

Soft Links

A soft link, also known as a symbolic link or symbolic link, is a reference to a file stored in a separate location. Unlike a hard link, a soft link is not a direct link to the physical file. Instead, it's a pointer to the file's location in the file system. This means that if the original file is moved or deleted, the soft link will no longer be valid. Soft links are identified by the l in the first column when using the ls -l command.

Creating a Soft Link

Creating a soft link is done using the ln command with the -s option. The basic syntax is as follows −

$ ln -s original_file soft_link

For example, if we have a file called “original.txt” and we want to create a soft link called “link.txt”, we would use the following command −

$ ln -s original.txt link.txt

This command creates a soft link to the original.txt file named “link.txt”. To verify the link, you can use the ls -l command to list the files in the directory. The output will show the file type and the destination file name.

$ $ ls -l link.txt 
lrwxrwxrwx 1 user user 12 Jan 17 16:31 link.txt -> original.txt

When to use Hard and Soft Links

Hard links are useful when you want to keep multiple references to the same file, but don't want to consume additional disk space. They are also useful when you want to create multiple names for the same file and want all names to be updated when the file changes. However, hard links have some limitations. For example, they cannot be used to link files on different file systems and also cannot be used to link directories.

On the other hand, soft links are useful when you want to make a reference to a file stored in a different location or on a different file system. They're also useful when you want to link to a file and don't want to worry about the file being moved or deleted. Soft links are also useful when you want to link to a directory. The main limitation of soft links is that they can become invalid if the original file is moved or deleted.

Conclusion

In conclusion, understanding the difference between hard links and soft links and when to use them is an important aspect of working with files in Linux. Hard links are useful when you want to keep multiple references to the same file and don't want to consume additional disk space, while soft links are useful when you want to create a reference to a file stored in a different location. or on a different file system. In short, hard links are direct links to the physical file, share the same inode number as the original file, cannot be created for a directory, and can only be created within the same file system. Soft links are a reference to the file location, can be created between different file systems, and become invalid if the original file is moved or deleted.