Tweak formatting & add another example

sheets/dd

@@ -1,26 +1,42 @@
 # Read from {/dev/urandom} 2*512 Bytes and put it into {/tmp/test.txt}
-# Note: At the first iteration, we read 512 Bytes.
-# Note: At the second iteration, we read 512 Bytes.
-dd if=/dev/urandom of=/tmp/test.txt count=512 bs=2
+# Note: both iterations each read 512 Bytes (the selected block size).
+dd if=/dev/urandom of=/tmp/test.txt count=2 bs=512
 
-# Watch the progress of 'dd'
-dd if=/dev/zero of=/dev/null bs=4KB &; export dd_pid=`pgrep '^dd'`; while [[ -d /proc/$dd_pid ]]; do kill -USR1 $dd_pid && sleep 1 && clear; done
+# Watch the progress of dd(1).
+dd if=/dev/zero of=/dev/null bs=4KB &
+export dd_pid=`pgrep '^dd'`
+while [[ -d /proc/$dd_pid ]]; do
+	kill -USR1 $dd_pid && sleep 1
+	clear
+done
 
-# Watch the progress of 'dd' with `pv` and `dialog` (apt-get install pv dialog)
-(pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror) 2>&1 | dialog --gauge "Running dd command (cloning), please wait..." 10 70 0
+# Watch the progress of dd(1) with pv(1) and dialog(1), both of which can be
+# installed with the following command: apt-get install pv dialog
+(
+	pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror
+) 2>&1 | dialog --gauge "Running dd command (cloning), please wait..." 10 70 0
 
-# Watch the progress of 'dd' with `pv` and `zenity` (apt-get install pv zenity)
-(pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror) 2>&1 | zenity --title 'Running dd command (cloning), please wait...' --progress
+# Watch the progress of dd(1) with pv(1) and zenity(1), both of which can be
+# installed with the following command: apt-get install pv zenity
+(
+	pv -n /dev/zero | dd of=/dev/null bs=128M conv=notrunc,noerror
+) 2>&1 | zenity --title 'Running dd command (cloning), please wait...' --progress
 
-# Watch the progress of 'dd' with the built-in `progress` functionality (introduced in coreutils v8.24)
+# Watch the progress of dd(1) with the built-in `progress` functionality, -
+# introduced in coreutils v8.24.
 dd if=/dev/zero of=/dev/null bs=128M status=progress
 
 # DD with "graphical" return
 dcfldd if=/dev/zero of=/dev/null bs=500K
 
-# This will output the sound from your microphone port to the ssh target computer's speaker port. The sound quality is very bad, so you will hear a lot of hissing.
+# This will output the sound from your microphone port to the ssh target
+# computer's speaker port. The sound quality is very bad, so you will hear a
+# lot of hissing.
 dd if=/dev/dsp | ssh -c arcfour -C username@host dd of=/dev/dsp
 
 # Show current progress without interruption (USR1)
 dd if=/dev/zero of=/dev/null & pid=$!
 kill -USR1 $pid
+
+# Create a 1GiB file with nothing but zeros, ready to mkswap(8) it.
+dd if=/dev/zero of=/swapfile count=1048576 bs=1024 status=progress