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

Navigate filesystem

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