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Links: Multiple Names for the Same File

Links let you access files from multiple locations. Like shortcuts. But different.

Here's the thing: Links are useful. You'll use them. Mostly symbolic links. Hard links are rare.

The Difference​

Hard link: Multiple names for the same file. All point to the same data.

Symbolic link: A pointer to another file. Like a shortcut.

My take: Use symbolic links. They're more common. Hard links are rare.

ln file.txt hardlink.txt          # Create hard link

What it does: Creates another name for the same file.

Real example:

$ echo "Hello" > original.txt
$ ln original.txt link.txt
$ cat original.txt
Hello
$ cat link.txt
Hello
$ echo "World" >> link.txt
$ cat original.txt
Hello
World

Both point to the same data. Change one, both change.

Limitations:

  • Only works on same filesystem
  • Can't link directories
  • All links are equal (no "original")

My take: Hard links are rare. You'll rarely use them. But they exist.

ln -s target link                  # Create symbolic link
ln -s /path/to/file link           # Absolute path
ln -s ../file.txt link             # Relative path

The -s flag: Makes it symbolic.

Real examples:

ln -s /var/www/html /var/www/current
ln -s ../config/production.conf app.conf

My take: Symbolic links are common. Use them. They're useful.

$ ln -s /etc/nginx/nginx.conf nginx.conf
$ ls -l nginx.conf
lrwxrwxrwx 1 ubuntu ubuntu 25 Dec 28 10:30 nginx.conf -> /etc/nginx/nginx.conf

The -> shows where it points. The l at the start means it's a link.

My take: Symbolic links are pointers. They point to other files. Simple.

$ ln -s /nonexistent/file.txt broken
$ ls -l broken
lrwxrwxrwx 1 ubuntu ubuntu 20 Dec 28 10:30 broken -> /nonexistent/file.txt
$ cat broken
cat: broken: No such file or directory

What happens: Link exists, but target doesn't. Link is broken.

My take: Broken links happen. Delete them. They're useless.

Common Uses​

Version Management​

ln -s /opt/app-v2.0 /opt/app-current
# Switch versions by changing the link

My take: Useful for deployments. Point to current version. Switch easily.

Convenient Access​

ln -s /var/log/nginx/access.log ~/nginx-access.log

My take: Create links for convenience. Access files from anywhere.

Configuration Management​

ln -s /etc/nginx/sites-available/mysite /etc/nginx/sites-enabled/mysite

My take: Common pattern. Available vs enabled. Links enable sites.

find /path -type l                 # Find all symbolic links
ls -l | grep "^l"                  # List links in directory
readlink link                      # Show where link points

My take: readlink shows where a link points. Useful for debugging.

rm link                            # Remove link (not the target)
unlink link                        # Same thing

My take: Removing a link doesn't remove the target. Just the link.

Common Mistakes (I've Made These)​

  1. Forgetting -s: ln file link creates hard link. ln -s file link creates symbolic link.

  2. Relative vs absolute paths: Absolute paths are safer. Relative paths break if you move the link.

  3. Linking to directories: Hard links can't link directories. Symbolic links can.

  4. Broken links: Links break if target is deleted. Clean them up.

  5. Circular links: Don't create links that point to each other. It breaks things.

Real-World Examples​

Enable Nginx Site​

sudo ln -s /etc/nginx/sites-available/mysite /etc/nginx/sites-enabled/mysite
sudo nginx -t
sudo systemctl reload nginx
ln -s /opt/app-v2.0 /opt/app-current
# Deploy new version
rm /opt/app-current
ln -s /opt/app-v3.0 /opt/app-current

What's Next?​

Now that you understand links, you can create shortcuts. Or learn about Disk Management to monitor storage.

Personal note: When I started, I'd copy files to multiple locations. Then I learned symbolic links. Now I link instead of copy. Saves space. Easier to manage. Links are useful.