Dd to create 10gb file First, make sure you’ve sufficient disk space to create a image file using dd: $ df -H To create 1MB file (1024kb), enter: I am using the bash shell and would like to pipe the out of the command openssl rand -base64 1000 to the command dd such as dd if={output of openssl} of="sample. Example 5: Create a bootable USB. I think I can use variables but I am however unsure how best to do so. This means that you have some 67 GB of unused space, so you can proceed with next command that will create 10 GB file: dd if=/dev/zero of=myharddisk. You can use dd to create a bootable USB and it’s just as easy as you might expect. txt 2. Based on the requirement of the data type and size, you can execute your dd command to create dummy data. I’ll create a sample file of known size, and generate an MD5 hash from it on several different storage mediums varying in IO capability. File C:\another1. After searching around for files of the right size, it turns out the easiest solution is to generate one yourself using the Linux command line. Feb 12, 2025 · How do I create 1 GB or 10 GB image file instantly with dd command under UNIX / Linux / BSD operating systems using a shell prompt? You can use dd command to create image files for network or file system testing. Jul 24, 2023 · It will be sufficient to accommodate the 10GB file we want to create. Then you need to convert that file into swap space, and enable it, so: sudo mkswap swapfile sudo swapon swapfile For more details, check: How do I add a swap?. Create a loop script that creates a 10GB file using dd where, upon completion, removes the file, then repeats 25 times or if CTRL+C is typed before the script gets the chance to exit. When you wish to create a very large file for test purposes, try this command: # dd if=/dev/zero bs=1024 count=2097152 of=. Sparse files are the fastest method to create empty files. Depending on your needs, you can The example below shows the syntax used. dd if=/dev/zero of=file. Jun 28, 2021 · In your dd command, you are trying to read from /dev/null. img /mnt/file Copy your files into your new mounted volume and when you finish unmount it: Jan 3, 2025 · We use these commands to create or generate the dummy or sample files. Apr 16, 2017 · Under non-embedded Linux or Cygwin (or any system with GNU coreutils) and FreeBSD: truncate -s 24m example. 24G . Using Fallocate to Create a 10GB File. txt is created. zip" (10GB) Create a large file using PowerShell with . Note: fallocate and dd allocated real/actual size for the file whereas truncate does not. So I tried to create a 10GB file with sudo dd if=/dev/zero of=/mnt/smbshare/VHD2. Aug 19, 2024 · For example, we’ll create a zip file with 10GB in sise. However, some file systems do not support this. echo "This is just a sample line appended to create a big file. Mar 18, 2024 · $ dd if=/dev/zero of=largerfile bs=1M count=666 $ dd if=file of=largerfile bs=1M conv=notrunc. Aug 22, 2024 · In this tutorial, we have covered the fundamentals of Linux file systems first. Conclusion. The contents of the file will consist of spaces. It's a bigger difference than I expected. txt >> dummy. If you want to create a file containing pseudo-random contents, run: See full list on cyberciti. Using the ‘dd’ Command. sudo dd if=/dev/zero of=/mnt/smbshare/VHD. bin. txt count=1024 bs=1024. github. When pushing the large image to the registry, it takes only few MB. Example: dd if=/dev/zero of=zeros. C:\>fsutil file createnew another1. You can use fallocate -l <size> <file_name> syntax to create a large file. Dec 22, 2021 · #DiskImage #DD #SDCardFull steps can be found at https://i12bretro. Here is a better solution. In this case, we first create largerfile with a size of 666 MiB. com, we're on a mission to simplify the way you share and receive files up to 10 GB, whether for business, educational, or personal use. $ dd if=/dev/zero of=10g. But using the dd command, you can do that too. This file will not contain any lines i. txt 32234567000. The size can be in KB, GB and TB. You can confirm the generated file size with the finder Get Info command, or by using ls: This means that you have some 12 GB of unused space, so you can proceed with next command that will create 10 GB file: dd if=/dev/zero of=myharddisk. Especially, if you are creating a large file with dozens of gigabytes it will take a considerable amount of time to write the file. 100MB. You can verify the size of the file by using du -sh largefile command as shown below. txt > foo Create a file filled with the last 14MB of data of another file: tail -c 14MB bar. tar largefile. bin filled with zeros, that has size of 20 megabytes : dd if=/dev/zero of=/tmp/zero_big_data_file. These commands do not include any feature or function to manipulate the text. The dd command is a versatile tool that can be used to create large files in Linux. Mar 21, 2010 · This means we can use it along with the dd command to quickly generate a file of any size. It reads data from an input file and writes it to an output file, making it an ideal choice for generating files of a specific size. Jun 19, 2013 · Create a file filled with \0s: dd if=/dev/zero of=foo. “Sparse file” means that file pretends to be 1GB in size, but as dd says during creation, 0 bytes were written to disk. Who We Are GetShared. That immediately returns EOF, so your dd command will exit after zero bytes. img. Jan 3, 2023 · This command is similar to dd, but it uses the fallocate() system call to pre-allocate space on the file system for the file, rather than writing zeros to the file. 04, so I’ll use dd to create a two gigabyte file using my system disk as effectively random input data. Notably, this has to be bigger than file. The files created by the dd and truncate are sparse files. biz Sep 26, 2008 · There are lots of answers, but none explained nicely what else can be done. To tell the difference with fallocate and dd (Whereas fallocate and dd allocate real storage, truncate does This means that you have some 67 GB of unused space, so you can proceed with next command that will create 10 GB file: dd if=/dev/zero of=myharddisk. If you want to create an even bigger file, say 10GB, the process remains the same. (Here is an example to It’s important to make sure that your source and destination files have the same ‘bs’ set for these operations, otherwise they will not have the intended results. Looking into man pages for dd, it is possible to better specify the size of a file. Test-Files Region: HIL. Mar 5, 2021 · fallocate (described at Quickly create a large file on a Linux system) works great to create large files very quickly, but the result is a 0 entropy large file, highly compressible. It is far quicker to use fallocate than to create a file by populating it with zeroes. txt bs=1k count=10485760 Sep 23, 2021 · The problem with the dd command is it takes a considerable amount of time to create the file. In this case, the following command will generate a 1 GB file. Jun 4, 2024 · How to Create a File-Based Filesystem Using dd Command on Linux. The dd command on Linux is powerful for cloning disks or creating ba May 5, 2025 · You can use this to create a tiny file that can compress extremely well This means you can create a 10GB file, and pass it to "gzip" and it becomes 10MB Used the following command to create this small "zip bomb" dd if=/dev/zero bs=1G count=10 | gzip -c > zipbomb. While you can try to create just a text file with some app like Notepad, it is very inconvenient when you need to create a huge file or many files at once. Transferring said files between hosts, for example, can provide a quick indication of your network throughput. bin 100+0 records in 200+0 records out 102400 bytes (102 kB) copied, 0,0114595 s, 8,9 MB/s Dec 20, 2014 · To create 4GB of swapfile, you can run: sudo dd if=/dev/zero of=swapfile bs=1K count=4M so by using multiplicative suffixes it's easier to count (1K * 4M = 4 GiB). ) using Fsutil. However, when the output file is not on a direct-access device and you use the seek flag, you also need read access to the file. html. txt > foo Oct 19, 2023 · To create a file of 1 GB, use it like this: fallocate -l 1G testfile1. Jan 21, 2023 · Creating an image file using the dd command; To create an image file using the dd command, the first step is to check the free disk space to create an image file, use the following command for this purpose: df -H. Oct 9, 2020 · Shrink or extend the file to a specified size. dd if=/dev/urandom of=/tmp/file bs=1M count=100 100+0 records in 100+0 records out 104857600 bytes (105 MB, 100 MiB) copied, 10,3641 s, 10,1 MB/s file /tmp/file && du -h /tmp/file /tmp/file: data 101M /tmp/file Use the dd command for creating swap files, copying disks, backup linux disks. ) Jun 23, 2017 · For example, this command will create a 1GB file called 1gb. In Linux, you can use the dd utility. First create a file of required size filled with 0xFF: $ dd if=/dev/zero ibs=1 count=102400 | LC_ALL=C tr "\000" "\377" >paddedFile. Some popular system text manipulating commands are dd, yes, fallocate, truncate, and touch. This can be faster than using dd if you just need to create an empty file of a certain size and don't need to fill it with data. img bs=1G seek=10 count=0. Create a 10GB file with filename “big” truncate -s 10G big or with time time truncate -s 10G big. You can use it to create a file of a specific size on Mac filled with zeros or random data. fsutil file createnew "C:\Users\<username>\Desktop\sample. The reason I would like to create the file is because I would like a 1GB file with random text. img bs=1M count=130 Then, format the image file: sudo hformat -l File /root/file. txt" 1073741824 Linux. bin bs=1M count=20 Oct 17, 2024 · The dd command is one of those commands that can create larger files with a reasonable time and without putting much pressure on the CPU. The dd command is a powerful utility for creating files with specific sizes. txt”: fallocate -l 1G largefile. : Apr 26, 2025 · Example: To create a 1 GB file named “largefile. Big files created from mkfile are full of zeroes. Its most common use is to create live Linux USBs. The dd command is one of the original Unix utilities, used to perform low-level Nov 6, 2022 · You can generate a dummy Test file of any size or type (txt, pdf, etc. 1GB. Just specify the size, which is 10GB in this case: fallocate -l 10GB users. Creating large files with the dd command. com is a team of dedicated professionals, software developers, and digital enthusiasts working together to bring you a seamless file-sharing experience. img count=1 bs=1 seek=$((10 * 1024 * 1024 * 1024 - 1)) This is very fast because only one byte is really written to the physical disc. head -c 14MB /dev/zero > foo Create a file filled with the first 14MB of data of another file: head -c 14MB bar. tar and then Tar will prompt for volume 2 like below :- Apr 18, 2017 · Here, we'll take advantage of a couple of built-in UNIX devices to create large files. Windows comes with a special console tool, fsutil. bin Greetings, I am wanting to create a 10GB zfs snapshot to use for some zfs send/receive bandwidth testing. The next step is to verify that our created image file actually exists. At the end of each operation, i. May 15, 2024 · In Windows, you can use the fsutil utility to create a new file with a defined number of bytes. txt bs=1G count=1. The dd command is used to copy and convert files. This file will have a size, but if we look at Jul 15, 2019 · For test purposes, I first tried with a 1GB file using the following commands. txt is consisting of a count of 10240 blocks, each of block size is 1M. ext4 /mnt/smbshare/VHD. The file is created instantly and takes up the full size. This is what I did: Code: mike@ubuntuzfs:/tan Dec 14, 2021 · This is probably the quickest way to create a large file. html----- Dec 3, 2024 · Here, we can explore three commands dd, mkfile, and truncate to make a file of a certain size on Mac. Lets say the largefile. For the examples below, I'm running macOS's version of dd. fsutil file createNew "C:temptest1. Oct 23, 2023 · 2. file This creates a file full of null bytes. The value 102400 is 1024 x 100, which will create a 100 Meg file called disk1. txt bs=1k count=10485760 Jan 21, 2019 · " dd if=/dev/zero of=dd. After that, we write our initial file to the beginning of largerfile. Thus, we end up with the contents of file padded to the size of largerfile. img bs=1000 count=0 seek=$[1000*1000*10] Caveats: This trick will work on ext3, ext4 & reiserfs – but will NOT work on FAT32 partitions as they have maximum file size of 4 GiB. io/tutorials/0525. The dd command inserts new-line characters only when converting with the conv=ascii or conv=unblock flags set; it pads only when converting with the conv=ebcdic, conv=ibm, or conv=block flags set. If every 10240 block is equal to 1M, Sep 26, 2008 · Just to follow up Tom's post, you can use dd to create sparse files as well: dd if=/dev/zero of=the_file bs=1 count=0 seek=12345 This will create a file with a "hole" in it on most unixes - the data won't actually be written to disk, or take up any space until something other than zero is written into it. Here we are creating an 8G file name largefile using fallocate -l 8G largefile command. txt bs=1M count=10240 "Your file dd. and more. Let's create a file whose contents is just a long series of null characters. head speeds are down ~40% compared to dd if=/dev/zero bs=64k and down ~25% compared to dd if=/dev/nvme0n1 bs=2M. txt for /L %i in (1,1,14) do type dummy. This creates 32GB file instantly which has random content. This tutorial will walk you through the steps to create, format, and use a file-based filesystem on a Linux system. Command dd to create files of specific size on Mac. As far as I know you can't tell dd to pad a file. For that purpose, I will be using the/dev/zero to create a file with a specific file size in the following manner: dd if Sep 28, 2021 · Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Dec 2, 2016 · I want to create a file of a specific size containing only printable strings in bash. Different versions provide different output. tgz is 150 Meg and we need to fit the file on two 100 Meg Zip drives. Nov 7, 2014 · In order to create a 10 GB temp file In Linux you can do this: fallocate -l 10G temp_10GB_file In Windows you can do this: fsutil file createnew temp_10GB_file 10000000000 but what about i May 12, 2018 · The best way to create random dump files is by using 'fsutil' in your command prompt. To make the math easier, it was helpful if I had files with round numbered sizes like 10MB, 20MB, or 100MB. Net. Create a file with a specific file size using the dd command. file This wil create a file consisting of 2097152 blocks of 1024 bytes, which is 2GB. This is going to create /tmp/zero_big_data_file. Disadvantage of sparse files Disadvantages are that sparse files may become fragmented. exe command-line in Windows 10. To verify the allocated storage space and display other file metadata, use the ls command with the -lh option: ls -lh users Aug 30, 2015 · Now, create an image file, the size is fixed: sudo dd if=/dev/zero of=/root/file. The key is to input the size of the file in bytes, so here are some common file sizes to save you from math: 1 MB = 1048576 bytes 100 MB = 104857600 bytes 1 GB = 1073741824 bytes 10 GB = 10737418240 Advantage of sparse files The advantage of sparse files is that storage is only allocated when actually needed: disk space is saved, and large files can be created even if there is insufficient free space on the file system. img bs=1024 count=2M takes time. Aug 2, 2010 · Occasionally, the need arises for files of a specific size. You can change the count value to anything you like. These commands are optimized to create text files of any size. In fact, this is one of the most popular use of the dd $ dd if=/dev/zero of=YOUR_IMAGE_FILE_NAME bs=1 count=0 seek=File_Size_HERE 这里，我们将在Linux机器上创建一个10GB的大文件来演示在Linux中创建大文件的过程。 在执行命令之前，请确保您的文件系统有足够的可用空间来存储输出文件。 Sep 23, 2014 · The experiment is simple. . img bs=1 count=0 seek=10G Create Large Dummy File in Linux. Both truncate or fallocate can create a file with some part of it filled with zeros or left uninitialized. img It works to get a 1GB ext4 filesystem, but dd is slow (10MB/s). test 1073741824. tgz. " > dummy. You need to read from something that can be actually read from, like /dev/random (as VladiBG suggests), /dev/zero (which is readable and always returns binary zero), or an existing file. I’m running Ubuntu 12. txt bs=14MB count=1 or. Creating a Large "Empty" File. So you total file size will be 10. /test. One easy way to build a file of a specific size is with the Data Description or dd command. Generally, when you create empty files, you don't get any options to create an empty file with a specific size. img bs=1000 count=0 seek=$[1000*1000*10] Caveats: This trick will work on ext3, ext4 & reiserfs - but will NOT work on FAT32 partitions as they have maximum file size of 4 GiB. To create a 10GB file with random data, you would use the following from your cmd prompt: dd if=/dev/random of=testfile. Aug 5, 2014 · I want to create a large file ~10G filled with zeros and random values. img After that, mount the image: sudo mkdir /mnt/file sudo mount -t hfs -o loop /root/file. Once we understand how the file system works on Linux systems, we can easily create files using terminal commands. gz In my NGINX server, I can use any NGINX config to detect unwanted requests. Learn how. exe file in the location you want to work with, or set up an environment variable for it. e. First up, I’ll create my sample file. 10GB. This is because writing all that zeros to disk like the following command does: dd if=/dev/zero of=2g. Now check the output file: ls -lh testfile1. Dec 28, 2018 · head speeds are indeed somewhere between dd bs=4k and dd bs=8k. large. Then, to create an image file with the desired size, for example, 1024kb (1MB), enter the following command: Dec 4, 2011 · So to get started, simply put the dd. My first thought was to use /dev/urandom:. Selecting a command May 31, 2013 · For example, to create a 1GB file called “LargeTestFile” on the desktop, the command would be: mkfile -n 1g ~/Desktop/LargeTestFile. To create the 10GB file on my Linux machine, I will run the following command. At GetShared. This command will create a file of size count*bs bytes, which in the above case will be 1Mb. dd, then rm, time it so we know exactly how long dd and rm took; So far, I'm thinking something along these lines: May 24, 2023 · I was recently testing file upload performance, and needed several large files of different sizes to test with. The file system free space Dec 8, 2022 · At this point, we can’t just create an empty file and start writing random data to it. In this post, we will see how to create larger files in a Linux system. Is there any way to create a new file of a specific size? Here are a few ways to create large files for your reference. test on my desktop: > fsutil file createnew c:\users\steve\desktop\1gb. tar -c -M --tape-length=102400 --file=disk1. But you can tell dd to write into a prepadded file. Dec 4, 2011 · So to get started, simply put the dd. The reads from /dev/zero are of course more CPU-limited, but for the SSD I/O queing also plays a role. img bs=1M count=1000 mkfs. I have tried using: dd if=/dev/urandom of=10Gfile bs=5G count=10 it creates a file of about 2Gb and exits with a exit status Jun 16, 2020 · will create a sparse file. So, how can a large, uncompressible file be created? Jun 12, 2009 · Extract from the link above: If you want to create a file with real data then you can use the below command line script. Verify Large Dummy File in Linux You can use dd to create a file consisting solely of zeros. Fsutil targets advanced users and 5. – Oct 31, 2018 · Sometimes you need to create a file of specific size for testing purposes. txt (Run the above two commands one after another or you can add them to a batch file. iro wouf gmy lfstkx ymnee xlxzv boflw edt wkuvskw jbxemk