💡
We can not directly view the raw directory entry because the filesystem manages it at a low level. However, we can view information about the files in a directory, including inode numbers, which are part of the directory entries using the commands ls -li or stat
A *link* is simply an additional directory entry for a file or directory. It is between the filename and the actual data stored on the filesystem. By creating links we can have multiple directory entries (names) for the same file or directory, allowing two or more names for the same thing.
## Hard Links
A hard link is a directory entry that points directly to the inode of a file. It acts as a separate file and refers to the exact spot on a hard drive. It is a mirror copy of the original file. Let's look at how to create hard links and find out how they work. To create the hard link, use `ln` command.
**Creating a hard link**:
1. Create an original file:
```bash
echo "Hello World!" > original.txt
```
![](https://cdn.hashnode.com/res/hashnode/image/upload/v1722515246589/10b8346f-29dd-4255-a86d-2bd244645599.png align="center")
2. Create a hard link:
```bash
ln original.txt hardlink.txt
```
![](https://cdn.hashnode.com/res/hashnode/image/upload/v1722515419279/39ddbedb-a62a-4697-89d3-b3d9e64a6cd5.png align="center")
3. Verify the inode numbers of the original and hard link files:
```bash
ls -i original.txt hardlink.txt
```
![](https://cdn.hashnode.com/res/hashnode/image/upload/v1722515575361/ae792d3d-6a12-4f1d-9933-4f0b15145c29.png align="center")
As we can see, both `original.txt` and `hardlink.txt` share the same inode number, indicating they point to the same file content.
**Editing the hard link**
4. Make changes to the hard link `hardlink.txt`:
```bash
echo "Nice to see you World" >> hardlink.txt
```
5. Check the content of the original file `original.txt`
```bash
cat original.txt
```
![](https://cdn.hashnode.com/res/hashnode/image/upload/v1722517146640/509eb247-eba0-42c1-8b47-3e8d389da581.png align="center")
As we can see, changes made to `hardlink.txt` are reflected in `original.txt` because they refer to the same inode.
**Deleting the original file**
6. Delete the original file:
```bash
rm original.txt
```
7. Check the content of the hard link `hardlink.txt`:
```bash
cat hardlink.txt
```
![](https://cdn.hashnode.com/res/hashnode/image/upload/v1722518809458/7a2cd0f7-2b91-436a-8a84-0dadc62cabc2.png align="center")
As we can see, the file content is still accessible through `hardlink.txt` since the inode and data blocks are preserved until *all* hard links are removed.
**Creating multiple hard links**
8. Create another hard link:
```bash
ln hardlink.txt another-hardlink.txt
```
9. Verify Inode numbers:
```bash
ls -li hardlink.txt another-hardlink.txt
```
![](https://cdn.hashnode.com/res/hashnode/image/upload/v1722519508799/ade1b0e6-5230-406d-abb4-4bf0c3bad95d.png align="center")
Again, both `hardlink.txt` and `another-hardlink.txt` share the same inode number, indicating they point to the same file content.
### Hard Link Advantages and Disadvantages
Hard links have the following advantages:
1. **Efficient Storage:** Hard links share the same inode and data blocks, which means no additional disk space is used for multiple hard links to the same file.
2. **File Availability**: As long as at least one hard link exists, the file's data remains accessible. Deleting one hard link does not delete the file.
3. **Performance**: Hard links are typically faster than symbolic links because they point directly to the inode without the need for path resolution.
4. **Transparency**: Hard links appear and behave like regular files. There is no distinction between the original file and its hard links.
5. **Consistency**: All hard links to a file are always up-to-date. Any changes made to the file through any hard link are immediately reflected in all other hard links.
While useful, there are some limitations to what hard links can do.
1. **Restrictions on Directories**: Hard links can only be created for regular files (not directories or special files).
2. **Single Filesystem Limitation**: Hard links cannot span multiple filesystems. They only work when the new hard link exists on the same filesystem as the original.
## Soft Links
A soft link (symbolic link) is a separate file that contains the path to another file or directory. Unlike hard links, soft links do not reference the inode of the target file directly but instead have their own inodes and contain the path to the target file or directory.
#### Creating a Soft Link
1. Create an original file:
```bash
echo "Hello World" > original.txt
```
2. Create a soft link using the command `ln -s`:
```bash
ln -s original.txt softlink.txt
```