Lesson 2.1: Introduction to the command line
How a command line session works: running a command, reading its output and its error messages, case sensitivity, command history, Tab completion and the two shortcuts you'll use every day.
14 min
You will learn to
- Run a command and read its output
- Read an error message and tell who reported what
- Explain why LS and ls are different commands
- Use history, the arrow keys, Tab completion, Ctrl+C and clear
Key terms
- Output
- What a command prints in the terminal after it runs.
- Error message
- A message explaining why a command couldn't do what you asked. It usually names who reports the error, what it was working on, and the problem.
- Case sensitivity
- Linux treats capital and small letters as different characters: ls, LS and Ls are three different names, and so are notes.txt and Notes.txt.
- Command history
- The list of commands you ran, kept by the shell. The Up and Down arrow keys move through it; history shows it.
- Tab completion
- Pressing the Tab key makes the shell complete a command or file name you started typing. Pressing it twice lists the possibilities.
- Ctrl+C and Ctrl+L
- Ctrl+C stops the command that is running (or throws away the line you are typing). Ctrl+L clears the screen, like clear.
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