====== dd ======

**General Information**

Using dd to create a USB bootable image.

**Checklist**
  * Distro(s): Any

----

===== The command =====
<code bash>
dd if=~/image.iso of=/dev/sdx oflag=direct  bs=2MB
</code>

==== Explanation ====

  * if = in file, the location of source image
  * of = output file, the location of the USB device. x is the drive letter.
  * oflag direct = bypass the cache and write direct to disk
  * bs = write in the specified block size

----

===== Get DD status =====

To get a progress report while dd is running, you need to open another virtual terminal, and then send a special USR1 signal to the dd process.

First, find out the process id of the dd process by running the following in the new virtual terminal.
<code bash>
pgrep -l '^dd$'
8789 dd
</code>

To send the USR1 signal to the dd prcoess:
<code bash>
kill -USR1  8789
</code>

As soon as the USR1 signal is detected, dd will print out the current statistics to its STDERR.
<code bash>
$ dd if=/dev/random of=/dev/null bs=1K count=100
0+14 records in
0+14 records out
204 bytes (204 B) copied, 24.92 seconds, 0.0 kB/s
</code>

Use the watch command to execute kill at a set interval. (every 10 seconds in this case)
<code bash>
watch -n 10 kill -USR1 8789
</code>

----

===== Alternative DD status =====

Another method of getting dd status is using pv.
PV "monitors the progress of data through a pipe".

The dd command then becomes:
<code bash>
dd if=~/image.iso | pv -petr | of=/dev/sdx oflag=direct  bs=2MB
</code>

pv options

  * -p : show progress bar
  * -e : estimated time remaining
  * -t : timer on, show total time running
  * -r : rate of data transfer