# Symbolic Links

UNIX filesystems have a feature called symbolic links, which are files that point to another file, called the target. They're similar to shortcuts in Windows.

There are two kinds of symbolic links: hard links and soft links.

## Hard Links

Hard links create a file which points to the same space on the hard drive as the file which is being linked to, rather than to that file itself.

```
/home/me/file      /home/you/file
    |                    |
 hard link           hard link
    |                   ,'
    V               _.-`
HARD DRIVE <....--``
```

A file won't be deleted until every hard link to it is deleted.

To create a hard link, you use the `ln` command with the source file, and the target hard linked file:

```bash
ln arrayDat.txt arrayHard.txt

ls
```

Notice that any changes you make to `arrayDat.txt` will be reflected in `arrayHard.txt`.

## Soft Links

Soft links create a file which points to the original file or directory.

```
/home/me/file <---Soft link--- /home/you/file
     |
     |
     V
HARD DRIVE
```

Soft links break if the original file is deleted.

To create a soft link, you use the `ln` command with the `-s` flag.

```bash
ln -s arrayDat.txt arraySoft.txt

ls -l
```

Notice that any changes you make to `arrayDat.txt` will be reflected in `arraySoft.txt`. The `ls` command will show that `arraySoft.txt` points to the file `arrayDat.txt`.

Your Luria home folder has a couple of soft links automatically set up pointing to storage servers so that common programs don't take up too much space on the head node.

[#home-directory](https://igb.mit.edu/computing-resources/luria-cluster#home-directory "mention")


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