dd is a command line utility that is used to convert and copy files on Linux. dd has many usages in Linux. For example, you can use dd to make a bootable USB thumb drive of your favorite Linux distribution. This is a very common usage of the dd command. In this article, I will show you how you can use dd to do various convert and copy operations in Linux. So, let’s get started.
Linux dd command. In short, the dd command lets you copy and convert a file. The tool offers some operands that you can use to specify what kind of formatting you want. Here's the generic syntax of the command as described on its man page.
If you want to make an ISO file of your CD or DVD disk. You can easily do that with the dd command.
Let’s say, you’ve inserted a DVD of a movie into the CD/DVD reader of your computer. Now, you want to create a ISO file from that DVD.
The first of these, the dd command, was discussed in part 1 of this series as a method for acquiring a forensic disk image. While many Mac utilities can create disk images, dd is an optimal choice for forensic use because it can create a disk image without mounting the drive (which would contaminate it). Dd can also be used with a variety of.
This will overwrite all partitions, master boot records, and data. Use the sudo command as well (sudo dd). Filling the disk with all zeros (This may take a while, as it is making every bit of data 0): dd if=/dev/zero of=/dev/sdX bs=1M Replace X with the target drive letter. If you are wiping your hard drive for security, you should.
My experience: Win32DiskImager did not detect u-SD through a USB-3 reader; dd for Windows, MinGW compiled dd, Unix Utils dd, and Linux dd VIA VirtualBox VM USB3 pass-through were all unacceptably slow; I have yet to find a Windows command line equivalent that can beat the 50MB/s write speeds I'm seeing with Rufus.
Dd' is an extremely basic, but powerful block level copy command built into all Linux and Unix operating systems (MacOS is UNIX based)' if' stands for input file (a.k.a the source file or location). In our use-case, this is the.ISO file.
First, run the following command to find the device name of your CD/DVD reader.
As you can see, the device name is sr0 in my case. So, I can access it as /dev/sr0
Now, you can make an ISO file of the CD/DVD disk with the following command:
Here, /path/filename.iso is the path and filename of your ISO file. In my case, I will save it to ~/Downloads/ubuntu.iso
As you can see, the ISO file is created. The disk write speed is about 29.4 MB/s and about 851 MB of data is written in total.
You should be able to find the ISO file in the directory where you saved it.
Making a Bootable USB Thumb Drive of Your Favorite Linux Distribution:
You can use dd to create a bootable USB thumb drive of your favorite Linux distribution.
To create a bootable USB thumb drive, you need a USB thumb drive of about 4GB or more in size and an ISO image of your preferred Linux distribution.
Let’s say, you want to make a bootable USB thumb drive of Ubuntu Server 18.04.1 LTS. You’ve downloaded the ISO file of Ubuntu Server 18.04.1 LTS and it’s in your ~/Downloads directory.
First, insert the USB thumb drive which you want to make bootable.
Now, run the following command to find the device name of your USB thumb drive.
As you can see, my 32GB USB thumb drive is listed here. The device name is sdb. So, I can access it as /dev/sdb
Now, run the following command to make a bootable USB thumb drive from the ISO image of your preferred Linux distribution.
Your USB thumb drive now can be used to install your desired Linux distribution.
Creating Virtual File Systems:
The dd command can be used to create file based virtual file systems. You can format, mount, store files etc from there.
Let’s say, you want to create a 512MB virtual file system.
To do that, run the following command:
NOTE: bs=1M means the block size is 1 MB and count=512 means the disk1.raw file will contain 512 blocks. 512 * 1MB = 512 MB. You can also set bs=1G to change the block size to 1 GB.
The 512MB raw file disk1.raw should be created.
As you can see, a new file disk1.raw is in my current working directory.
Now, you can format the file disk1.raw file as any filesystem you want. I will format it as EXT4 filesystem.
To format the disk1.raw file as EXT4 filesystem, run the following command:
NOTE: Here, datastore1 is the label of the virtual disk. You may change it if you want.
A virtual EXT4 filesystem should be created.
Now, make a new directory where you can mount the virtual filesystem with the following command:
Now, mount the virtual filesystem to the newly created directory with the following command:
As you can see, the virtual filesystem is mounted correctly.
This is great for testing.
Wiping The Whole Disk:
You can use the dd command to wipe the partition table off of your disk or USB thumb drives.
Let’s say, you want to wipe off the partition table off of the disk /dev/sdb. To do that, run the following command:
The whole partition table of your disk should be removed. This is a very destructive operation. You will not be able to recover your partitions anymore. If you want to use this disk again, you will have to create a new partition table.
If you want to sell your hard drive or SSD to someone else, then it is always safe to completely wipe out all your personal data. Complete wipe out means replacing the contents of the whole disk with either zeros or random values. So, the new owner of the disk won’t be able to recover any of your personal data.
If you want to replace the contents of the whole disk with zeros, then you can use dd as follows:
This will take a long time to complete.
If you want to replace the contents of the whole disk with random values, then you can use dd as follows:
This will take a long time to complete as well.
Where to Go Next?
The dd command has a lot of options that may come in handy. You may checkout the dd manpage for more information on all the supported command line options and usages of the dd command.
To access the manpage of dd, run the following command:
Dd Command For Mac Iso
So, that’s how you use dd command on Linux to do various tasks. Thanks for reading this article.
Data Duplicator, convert and copy a file. Copy standard input to the standard output.
Input data is read and written in 512-byte blocks. If input reads are short, input from multiple reads are aggregated to form the output block. When finished, dd displays the number of complete and partial input and output blocks and truncated input records to the standard error output.
ascii, oldascii The same as the unblock value except that characters are translated from EBCDIC to ASCII before the records are converted. (These values imply unblock if the operand cbs is also specified.) There are two conversion maps for ASCII. The value ascii specifies the recommended one which is compatible with AT&T System V UNIX. The value oldascii specifies the one used in historic AT&T UNIX and pre-4.3BSD-Reno systems. block Treats the input as a sequence of newline or end-of- file terminated variable length records independent of input and output block boundaries. Any trailing new-line character is discarded. Each input record is converted to a fixed length output record where the length is specified by the cbs operand. Input records shorter than the conversion record size are padded with spaces. Input records longer than the conversion record size are truncated. The number of truncated input records, if any, are reported to the standard error output at the completion of the copy.
ebcdic, ibm, oldebcdic, oldibm The same as the block value except that characters are translated from ASCII to EBCDIC after the records are converted. (These values imply block if the operand cbs is also specified.) There are four conversion maps for EBCDIC. The value ebcdic specifies the recommended one which is compatible with AT&T System V UNIX. The value ibm is a slightly different mapping, which is compatible with the AT&T System V UNIX ibm value. The values oldebcdic and oldibm are maps used in historic AT&T UNIX and pre-4.3BSD-Reno systems. lcase Transform uppercase characters into lowercase characters. noerror Do not stop processing on an input error. When an input error occurs, a diagnostic message followed by the current input and output block counts will be written to the standard error output in the same format as the standard completion message. If the sync conversion is also specified, any missing input data will be replaced with NUL bytes (or with spaces if a block oriented conversion value was specified) and processed as a normal input buffer. If the sync conversion is not specified, the input block is omitted from the output. On input files which are not tapes or pipes, the file offset will be positioned past the block in which the error occurred using lseek(2). notrunc Do not truncate the output file. This will preserve any blocks in the output file not explicitly written by dd. The notrunc value is not supported for tapes. osync Pad the final output block to the full output block size. If the input file is not a multiple of the output block size after conversion, this conversion forces the final output block to be the same size as preceding blocks for use on devices that require regularly sized blocks to be written. This option is incompatible with use of the bs=n block size specification. sparse If one or more output blocks would consist solely of NUL bytes, try to seek the output file by the required space instead of filling them with NULs, resulting in a sparse file. swab Swap every pair of input bytes. If an input buffer has an odd number of bytes, the last byte will be ignored during swapping. sync Pad every input block to the input buffer size. Spaces are used for pad bytes if a block oriented conversion value is specified, otherwise NUL bytes are used. ucase Transform lowercase characters into uppercase characters. unblock Treats the input as a sequence of fixed length records independent of input and output block boundaries. The length of the input records is specified by the cbs operand. Any trailing space characters are discarded and a newline character is appended.
Where sizes are specified, a decimal, octal, or hexadecimal number of bytes is expected. If the number ends with a b, k, m, g, or w, the number is multiplied by 512, 1024 (1K), 1048576 (1M), 1073741824 (1G) or the number of bytes in an integer, respectively. Two or more numbers can be separated by an x to indicate a product.
When finished, dd displays the number of complete and partial input and output blocks, truncated input records and odd-length byte-swapping blocks to the standard error output. A partial input block is one where less than the input block size was read. A partial output block is one where less than the output block size was written. Partial output blocks to tape devices are considered fatal errors. Otherwise, the rest of the block will be written. Partial output blocks to character devices will produce a warning message. A truncated input block is one where a variable length record oriented conversion value was specified and the input line was too long to fit in the conversion record or was not newline ter- minated.
Normally, data resulting from input or conversion or both are aggregated into output blocks of the specified size. After the end of input is reached, any remaining output is written as a block. This means that the final output block might be shorter than the output block size.
The name dd is thought to be an allusion to the DD statement found in IBM's Job Control Language (JCL), where the acronym stands for 'Data Description'.
If dd receives a SIGINFO signal, the current input and output block counts will be written to the standard error output in the same format as the standard completion message. If dd receives a SIGINT signal, the current input and output block counts will be written to the standard error output in the same format as the standard completion message and dd will exit.
Clone the drive hda onto an image file: $ dd if=/dev/hda of=/image.img
Copy a CD or DVD disc to a .iso image file, first unmounting the disc: sudo umount /dev/dvd-device dd if=/dev/dvd-device of=dvd.iso bs=2048 conv=sync,notrunc # dvd-device will typically be dvd for a dvd disc or cdrom for a cdrom disc.
Dd Command Mac Progress
Clone a hard drive to a zipped image file in 100Mb blocks: $ dd if=/dev/hda bs=100M | gzip -c > /image.img
Create a 10 KB file filled with random data (10 x 1K blocks): $ dd if=/dev/random of=random.bin bs=1024 count=10
Completely wipe the hard drive hdz by overwriting it with random data: $ dd if=/dev/urandom of=/dev/hdz
Dd Command For Mac Installer
“Success isn't something you chase. It's something you have to put forth the effort for constantly. Then maybe it'll come when you least expect it. Most people don't understand that” - Michael Jordan
Related macOS commands:
Apple Disk Utility can create DMG files or ISO files (select the 'CD/DVD Master' option) cp - Copy one or more files to another location. cpio - Copy files to and from archives. hdiutil - Manipulate iso disk images. install - Copy files and set attributes. mv - Move or rename files or directories. tr - Translate, squeeze, and/or delete characters.