Some Alternatives to dd

dd is a very old command. It was published over 50 years ago in 1974 for Unix. This age makes the syntax of its commands quite unusual. Given that this command is frequently used to overwrite partitions and entire storage devices the unusual nature of its command syntax is dangerous. It’s a rite of passage for every Linux Sysadmin to dd over something viable, destroying it.

There are now more modern commands that can perform the same job as dd using much more standard syntax.

Writing an ISO to a partition or device

This job occurs when you have a Linux ISO and want to write it over a USB partition or the entire device. The dd command looks like the following:

dd if=linux.iso of=/dev/sda1 bs=4MB status=progress

• if= Input file or what is supplying the data
• of= Output file or where the data is getting written to
• bs=4MB Block size
• status=progress Print the status of the write operation

Using cp

The cp command is capable of performing this task as well:

cp linux.iso /dev/sda1

Using cat

The cat command will print the contents of an input and send it to standard out. This means that we can simply cat the iso file onto the destination:

cat linux.iso > /dev/sda1

The > redirects the output from cat, standard output, to be written to a file, partition, or device. The only problem with this command is that it will not print any status information.

You can use the pv or pipe viewer command to give the status of the write:

cat linux.iso | pv > /dev/sda1

Using pv

You can also simply use the pv command as another replacement for dd:

pv linux.iso -Y -o /dev/sda1

• -Y This synchronizes the buffers after every write operation making the status bar more accurate for slow disks
• -o This specifies the output

Bonus - Creating an arbitrary file with head

The other main use I put dd to is to create a large file when I need one. I use the following command to create a 1GB file:

dd if=/dev/zero of=big.file bs=1MB count=1024 status=progress

• if=/dev/zero Input data from /dev/zero
• of=big.file Output file or where the data is getting written to
• bs=1GiB Block size
• count=1 How many blocks to write
• status=progress Print the status of the write operation

The input, /dev/zero is an endless and very rapid stream of zeros. These are nulls (binary zeros, not the ASCII kind i.e. “0”). This means that running this command will create a 1GB file full of the same character.

The head command will print the beginning number of lines, characters, or bytes of an input. This means that we can use it on /dev/zero:

head -c 1G /dev/zero > big.file

• -c 1G head will only write the first 1GB of data from /dev/zero