> For the complete documentation index, see [llms.txt](https://eric-lo.gitbook.io/lab9-filesystem/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eric-lo.gitbook.io/lab9-filesystem/important-commands/viewing-with-hex-editor.md).

# Viewing with Hex Editor

In order to analyze the file system, we have to view it using hexadecimal editor.

There are two common hex editors in Ubuntu:

* hexedit
* xxd

Now try to view the disk file by hexedit. If you haven't unmount it, do it now.

In the terminal,

```
$ hexedit test.disk
```

![](/files/-Lp-5bN3bv52RU6TI9G3)

There are three columns in the output:

1. Line number in hexadecimal
2. Content in Hexadeciaml
3. Content in ASCII

For one hex digit, 4 bits (2^4 = 16) are needed to represent 0-15(0-F). Two hex digits occipies 8bits = 1 byte, therefore they are in group of two.