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Basic first

You can use up arrow to go to previous command.

If your system does not support up/down arrow key, you can use Ctrl-p or Ctrl-n.

reset to reset.

Ctrl-c to break off command.

Read the docs​

man for getting help. E.g. man ls to see info about ls user commands.

Then press space to move down, press b to move up. / for search, write the word then enter, n to find next occurs.

q to exit.

Anatomy of a command​

  • Words seperated by spaces
    • First word: the command to run
    • Other words: arguments
  • Options are arguments starting with -
    • It changes behavior of the command

Some for user interface:

  • Space bar to move down, b to move up a page.
  • / for search, n for next match.
  • q for quit.

Some commands​

pwd: path to work directory.

ls: list contents. ls -a: list all files including hidden. ls -l: long format.

a and l above called options. You can combine both by using ls -a -l or just ls -la.

cd somePathToDir: change directory by go somePathToDir.

cd: go to home directory.

To get the suggestion when cd, use tab. E.g. in bash:

$ cd D# then hit tab twice
# shows all directories start with 'D'
Desktop/    Documents/  Downloads/

$ cd Doc# then tab
$ cd Documents/

With zsh, you only to tab once to show all suggestions, then continue to tab to choose the directory.

Work with text files​

touch file1 file2: create empty files.

If you want space in filename, use single quote or backlash \ escape

mkdir someDir: create directory.

rm someFile: delete file permanently.

List files​

cat someFile: show content of someFile. Use less someFile if the file is large & complex (then you can use space and b to move around, etc.).

file someFile: info of someFile.

open someFile: open a file (macOS).

Edit with Nano​

nano someFile, it will show some instructions at bottom.

Edit with Vi​

vi someFile.

Vi has different modes:

  • Command mode (default):
    • X: delete a character.
    • DD: delete whole line.
    • : (shows : at the bottomU, then do below before enter:
      • w: write (save file's changes).
      • q: exit vi. q!: exit without saving changes.
      • wq: write and exit.
  • Insert mode:
    • Press i to enter this mode (at the bottom shows -- INSERT --).
    • Press esc to exit this mode.

Case sensitivity in filenames​

Default filesystem on macOS is not case-sensitive.

Characters to avoid:

  • Quotes: `` ' "
  • Brackets, parens: {} () <> []
  • Interpunction: ! ? & | : ; \ ^
  • Other: $ @ ~ * #
  • Whitespace: tab delete backspace newline

Log in to another system using SSH​

ssh someLinuxServer

The prompt will also change corresponding to the session.

exit, logout