How to use symbolic link

What is Symlink?

Symlink is a file that points to the original file or directory path.

Why Should We Use Symlink?

By using symlink, you can avoid duplicating data, organize files efficiently, and save disk space.

Example

Hypothetical File Structure

Suppose you have the following directory structure on your computer:

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/home/
│
├── user/
│   ├── documents/
│   │   ├── report.txt
│   │   └── notes.txt
│   │
│   └── projects/
│       └── project1/
│           ├── data.csv
│           └── analysis.py

Creating a Symlink

Let’s say you frequently need to access data.csv from the projects/project1/ directory while working in the documents directory. To make this easier, you can create a symlink in documents folder that points directly to data.csv. From your terminal, you would first navigate to the documents directory:

Commands to Create the Symlink

First, you should go to the directory (documents) that you want to link the targeted file (data.csv).

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cd /home/user/documents

Then, you can create the symlink by using the following command:

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ln -s ../projects/project1/data.csv data_link.csv

Updated File Structure with Symlink

Now your directory structure looks like this:

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/home/
│
├── user/
│   ├── documents/
│   │   ├── report.txt
│   │   ├── notes.txt
│   │   └── data_link.csv -> ../projects/project1/data.csv
│   │
│   ├── photos/
│   │   └── vacation/
│   │       ├── img001.jpg
│   │       └── img002.jpg
│   │
│   └── projects/
│       └── project1/
│           ├── data.csv
│           └── analysis.py

How Does the Symlink Work?

The symlink data_link.csv in the documents directory doesn’t contain the data itself but is merely a reference to data.csv located in /home/user/projects/project1/. When you access data_link.csv, the operating system redirects you to the original data.csv file. If data.csv is updated, those changes will appear when accessing it through data_link.csv as well.

Viewing the Contents of the Symlink

If you run a command to view the contents of data_link.csv, such as:

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cat data_link.csv

This will display the contents of data.csv, because the symlink directs to that file.

What Happens When the Linked File is Deleted?

When the target of symbolic link (symlink) is deleted, the symlink becomes what is commonly referred to as a “dangling link” or “broken link”. This means that the symlink still exists but points to a non-existent file or directory.

To prevent issues related to dangling symlinks, especially in scripts or automated systems, it’s good practice to check that a symlink’s target exists before accessing it.

How to Check the Existing Symlinks?

If you want to see details about files and symlinks in a directory, you could use ls -l like this:

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ls -l /path/to/directory