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What is /dev/zero in Linux?

One of the special device files in Linux, /dev/zero is used for creating files filled with zeroes.

Sagar Sharma

Warp Terminal

In Linux, device files are quite special as they provide applications to interface with device drivers which also include the /dev/zero.

So in this article, I will walk you through what it is and why it is used for.

A Zero Generator of Linux

Yes, you guessed it right!

The /dev/zero is a dummy file that is used to create files filled with zeroes.

But why would you want to create a file filled with zeroes? Well, there are various use cases for nuking the file with zeros. Such as:

  • Formatting drive and filling space with zeros to override old data.
  • Creating dummy files for experiments.
  • Creating a temporary swap file.

Sounds interesting. Right?

So let's have a look at how you can use this powerful utility.

How to use /dev/zero

Here, I will be showing you two use cases of /dev/zero:

  1. Formatting disk partitions with zeroes.
  2. Creating dummy files.

So let's start with creating a dummy file filled with zeros.

How to create a dummy file in Linux

To create a dummy file, you would need to follow the given command syntax:

dd if=/dev/zero of=Filename bs=Block_Size count=sets_of_blocksize


  • of=Filename is where you can indicate the path and name of the file you want to create,
  • bs=Block_size is where you will enter the size of each block such as 1MB.
  • count=sets_of_blocksize is where you have to specify the count of the block size. such as if you want to create a file worth 1 gigabyte, you will use a 1Mb block and set the count to 1024.

For example, Here I have created a dummy file named Dummy worth of 100MB:

dd if=/dev/zero of=Dummy bs=1MB count=100
how to create dummy files in Linux

How to format drive with zeroes in Linux

This process may take quite a long especially if you use using a drive with slow write speeds.

The first step in formatting is to list available disks in Linux. Here, I have used the lsblk command:

list available disks in linux

Here, my target disk is sdb1 mounted at /media/sagar/Q1.

Once you find out the name of the drive you want to work with, you will have to unmount that partition.

This can easily be done using the umount command:

umount TargetDrive

For me, its sdb1:

umount /dev/sdb1

Now, all you need to do is use the following command to format the disk:

sudo dd if=/dev/zero of=TargetDrive bs=1M
format disk with zeroes in Linux

Ignore the error message as you are wiping the disk from the beginning.

And as you can see, the drive has been formatted successfully!

It is not advised to use the `dd` command to create a file using the `/dev/zero` special file on SSDs. This is to prevent write amplification which negatively impacts the endurance of an SSD.

Wrapping Up

I would recommend using /dev/random instead of /dev/zero if you want to format the disk and make it a lot harder to recover old data.

This was a little explanatory guide on how you can use the /dev/zero. I hope you will find this helpful.

And if you have any queries, let me know in the comments.

Sagar Sharma