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Symbolic Links

A symbolic link, usually called a symlink for short, is a special kind of file that points to another file or directory.

It's a lot like a shortcut in a GUI. The symlink has its own path, but when you use it, the operating system follows the link to the target.

Link Command

The ln command creates links. To create a symbolic link, use the -s flag:

ln -s target_path link_path

Note, the path to the target comes first, then the path where the symlink will be created. For example:

ln -s documents/important.txt important.txt

That creates a symlink in the current directory named important.txt, which points to documents/important.txt.

A relative target is resolved from the symlink's location, not from wherever you run ln.

You can use either a relative or an absolute path for the target. Both options have tradeoffs!

If you use an absolute path, you can usually move the symlink without a problem, but moving the target will break the symlink. If you use a relative path, the symlink will continue to work as long as its position relative to the target stays the same. For example, you could move a parent directory containing both the symlink and the target.

Symlinks vs. Copies

A symlink is not the same as a copy: it doesn't duplicate the file's contents. It just creates another path that points to the original. That means:

If the target file changes, the symlink shows the new contents.
If you delete the symlink, the target file still exists.
If you delete the target file, the symlink breaks.

You can use ls -l to see where a symlink points:

important.txt -> documents/important.txt

Assignment

WorldBanc's T-Bills product is filed under credit_cards, but Treasury Bills are an investment, not a credit card. You'll move the file where it belongs, then leave a symlink at the old path so any old documentation that still points to credit_cards/tbills.txt keeps working, without keeping a second copy of the file.

Navigate into the worldbanc/public/products directory.
Create a new investments directory.
Move credit_cards/tbills.txt into the investments directory.
Navigate into the credit_cards directory.
Create a symlink named tbills.txt that points to the file's new home in investments.
- Use a relative target (resolved from credit_cards).
- credit_cards and investments are siblings, so the target needs to go up one level first (../investments/tbills.txt).
Run ls -l (lowercase L) to confirm that the symlink exists.

Paste the ls -l output and submit it.