In this short tutorial, we will go over the basics of symbolic links in Linux and create a simple bash script to get the target of the symbolic link.
Types of Symbolic Links
There are mainly two types of symbolic links, namely:
Hard Links:
Hard links are direct pointers to a file or directory within a filesystem. Hard links are creatable only in the same filesystem as the target file.
Soft Links:
On the other hand, Soft links are indirect shortcuts to a file or directory and can exist anywhere within a filesystem. Soft links can point to file in a different filesystem.
How to Create Symbolic Links
To create a symbolic link in Linux, we use the ln command. Executing the command with no options creates a hard link to the specified target file.
The general syntax for the ln command is:
As mentioned, the above command will create a hard link to the target file. To create a soft symbolic link, use the -s option as:
Example #1
Let us take the file auth.log in /var/log. We can create a link to the file in our home directory using the command as:
The above command will create a link pointing to the main file. We can verify this by using the ls command:
Example #2
You can also perform a similar operation on a directory. To create a link to /var/log, we use the command:
Similarly, a soft link is created pointing to the target /var/log directory:
How to Remove Symbolic Links
To remove a symbolic link, we use the command unlink followed by the path to the symbolic link to remove.
For example:
NOTE: If you delete the target file or directory, remove the symbolic link because leaving it creates a broken link.
How to Get Symbolic Link Target File or Directory
Every symbolic link points to a target file or directory (unless broken). To fetch the target file/directory of a symlink, we use this command that shows the target of a symlink.
For example, to get the target of the auth.log file we created in an earlier section, we can do:
/val/log/auth.log
A Simple Bash Script to Get Symlinks
Using the concepts above, we can assemble a simple bash script that accepts a path and lists all the symlinks and their target files or directory.
A simple script such as the one provided below should do the trick.
echo "Provide the directory to evaluate:"
read target_dir
cd $target_dir
links=$(find . -maxdepth1 -type l -ls | awk '{print $11}')
for link in links
do
echo "$link -> $(readlink $link)"
done
The script starts by asking the user for the directory to evaluate. Then, the script goes to the provided directory and finds all the symbolic links inside the directory, and passes the output to awk.
Awk parses the output and locates only the symbolic links, and saves them to a variable called links.
We then create a loop that grabs each link in the links and evaluates their target value using the readlink command.
Finally, we echo the symbolic link and the target directory. Below is an example output:
In the above example, we find all the symlinks in the /etc directory and print their target file or directory.
Conclusion
In this tutorial, we discussed the basics of using symbolic links in Linux. We then created a simple script to find symbolic links in a specified directory and show their source and target.
Thank you for reading!
