The xxd utility is a command-line tool available in Linux that allows you to dump a binary file in hexadecimal, octal, decimal or binary format. It is especially useful for viewing and analyzing the contents of binary files such as executables and image formats. This article will provide you with a step by step guide on how to use the xxd hex dumper utility in Linux.

Step 1: Install xxd

The xxd tool is generally included in most Linux distributions. In case it is not installed in your system, you can install it using the following command:

`sudo apt-get install xxd`

Alternatively, you can use the package manager available on your Linux distribution to install it.

Step 2: Basic Usage

To use the xxd utility, navigate to the location of the binary file using the terminal, and then type the following command:

`xxd filename.bin`

This will display the contents of the binary file in hex format in the terminal.

Step 3: Additional Options

The xxd utility also supports several additional options to customize the way the output is displayed. Below are some of the most commonly used options:

– `-b` – displays the output in binary format
– `-c` – specifies the number of bytes to be displayed in a single line
– `-g` – specifies the number of bytes per group when displaying hex output
– `-l` – specifies the number of bytes to be displayed
– `-u` – displays the output using uppercase letters
– `-v` – displays the ASCII representation along with the hex output

For example, the following command will display the contents of the binary file using 8 bytes per line:

`xxd -c 8 filename.bin`

Step 4: Redirecting Output

You can also redirect the output of the xxd command to a text file using the standard output redirection operator `>`.

For example, to save the output of the xxd command to a file called `output.txt`, run the following command:

`xxd filename.bin > output.txt`

Step 5: Modifying Files with the xxd Utility

Besides just displaying the contents of a binary file, the xxd utility can also be used to make changes to the file.

To modify a binary file using the xxd utility, follow these steps:

– Dump the contents of the file into a new file
– Edit the new file using a hex editor
– Convert the edited file back to binary

For example, to modify a binary file `filename.bin` using the xxd utility, run the following commands:

1. Dump the contents of the file to a new file:
`xxd filename.bin > output.txt`

2. Open the new file in a hex editor and modify the necessary bytes.

3. Convert the modified file back to binary:
`xxd -r output.txt > newfilename.bin`

Conclusion

The xxd hex dumper utility is a powerful tool that allows you to analyze and modify binary files with ease. With the ability to customize output and redirect output to files, it makes analyzing binary files in Linux a breeze. Combine xxd with a hex editor and you have an efficient method to modify and analyze binary files.