ln

Understanding Hard Links and Symbolic Links

Before jumping into the ln command itself, let’s clarify the difference between hard links and symbolic links:

Hard Links: A hard link is essentially another directory entry pointing to the same inode as the original file. Think of it as creating an alias. Deleting one hard link doesn’t affect the others; the file data remains intact as long as at least one hard link exists. Hard links cannot span different filesystems.

Symbolic Links (Soft Links): A symbolic link, also known as a soft link, is a file that contains a path to another file. It’s like a shortcut. Deleting a symbolic link doesn’t affect the original file; however, if the original file is deleted, the symbolic link becomes broken (pointing to a non-existent file). Symbolic links can span different filesystems.

Using the ln Command

The basic syntax of the ln command is:

ln [OPTION]... TARGET LINK_NAME

Where:

• TARGET: The path to the original file (the target of the link).
• LINK_NAME: The desired name for the link.

Creating Hard Links

To create a hard link, simply use the ln command without any options:

ln myfile.txt myfile_link.txt

This creates a hard link named myfile_link.txt pointing to the same inode as myfile.txt. Both files will now have the same size and modification times. Try running ls -li myfile.txt myfile_link.txt to verify they share the same inode number (the first number in the output).

You can also create hard links in different directories:

ln myfile.txt /home/user/documents/myfile_link.txt

This creates a hard link in the /home/user/documents directory. Remember, hard links cannot cross filesystems.

Creating Symbolic Links

To create a symbolic link, use the -s option:

ln -s myfile.txt myfile_symlink.txt

This creates a symbolic link myfile_symlink.txt that points to myfile.txt. The ls -l command will show a l indicating it’s a symbolic link, and the output will include the path to the target file.

You can create symbolic links that point to directories as well:

ln -s /home/user/documents mydocs_link

Handling Existing Links

If you try to create a hard link with a name that already exists, you’ll receive an error. For symbolic links, the existing file will be overwritten if it’s not a directory.

Advanced Usage: Relative and Absolute Paths

The TARGET and LINK_NAME in the ln command can be either relative or absolute paths. Relative paths are relative to the current working directory.

ln -s data/myfile.txt myfile_link.txt



ln -s /home/user/data/myfile.txt /tmp/myfile_link.txt

Troubleshooting Broken Symbolic Links

If the original file of a symbolic link is deleted, the link becomes broken. You can identify broken symbolic links using ls -l: they’ll appear with an indication like -> followed by a path that doesn’t exist. To fix this, either restore the original file or remove the broken symbolic link using rm.

This guide offers a solid foundation for effectively utilizing the ln command in your Linux workflow. Further exploration of its capabilities can improve your Linux administration skills.