# File System Object

Nix implementations use a simplified model of the file system, which consists of file system objects.
Every file system object is one of the following:

 - File

   - A possibly empty sequence of bytes for contents
   - A single boolean representing the [executable](https://en.m.wikipedia.org/wiki/File-system_permissions#Permissions) permission

 - Directory

   Mapping of names to child file system objects

 - [Symbolic link](https://en.m.wikipedia.org/wiki/Symbolic_link)

   An arbitrary string.
   Nix implementations do not assign any semantics to symbolic links.

File system objects and their children form a tree.
A bare file or symlink can be a root file system object.

Nix does not encode any other file system notions such as [hard links](https://en.m.wikipedia.org/wiki/Hard_link), [permissions](https://en.m.wikipedia.org/wiki/File-system_permissions), timestamps, or other metadata.

## Examples of file system objects

A plain file:

```
50 B, executable: false
```

An executable file:

```
122 KB, executable: true
```

A symlink:

```
-> /usr/bin/sh
```

A directory with contents:

```
├── bin
│   └── hello: 35 KB, executable: true
└── share
    ├── info
    │   └── hello.info: 36 KB, executable: false
    └── man
        └── man1
            └── hello.1.gz: 790 B, executable: false
```

A directory that contains a symlink and other directories:

```
├── bin -> share/go/bin
├── nix-support/
└── share/
```
