Chapter 5: Text, editors and the shell environment

grep, vim and Bash quiz

Twelve questions across the whole chapter. Each answer explains why. Aim for nine before moving on to chapter 6.

• Which sends both output and errors of a command into one file, all.log?
• What does cmd 2> /dev/null | wc -l count?
• Why is cmd 2>&1 > file different from cmd > file 2>&1?
• Which grep pattern matches lines that start with a digit?
• Which command shows lines of app.conf that are neither comments nor empty?
• In basic grep syntax, how do you match one or more digits?
• You are in vim and typed text in the wrong place. Which keys undo it?
• Which vim command saves and quits?
• Which vim keys delete three lines?
• Why does a command you put in ~/bin run without typing its full path?
• Where would you set an environment variable for every user on the system?
• What does LANG=C ls run?