Command Line Fun Environment Variables echo $PATH   export b=10.11.1.220 ping -c 2 $b There are many other environment variables defined by default in Kali Linux. We can view these by running env at the command line:   Bash History While working on a penetration test, it's important to keep a record of commands that have been entered into the shell. Fortunately, Bash maintains a history of commands that have been entered, which can be displayed with the history command. 1 Holding down C and pressing r will invoke the reverse-i-search facility. Type a letter, for example, c , and you will get a match for the most recent command in your history that contains the letter "c". Keep typing to narrow down your match and when you find the desired command, press I to execute it.