My personal cheatsheet for the Mac OS Terminal

In order to use commands you'll need a program that reads and executes them. That program is called shell, which runs inside the Terminal. Some commands are builtin and some commands are external programs. You can check that by using the type command.

You can define a shell variables and their values by assigning them:

VAR=3 

Print it out using a leading $

echo $VAR

The Shell comes with some default Variables.

Use printenv to print all of them. If you want to create an environment variable that is available to all programms started from that shell you need to use

export VAR=3 

or

export VAR

if you previously defined VAR.

Programs are scattered all over the filesystem, in directories like /bin and /usr/bin. The variable PATH tells the shell where to look.PATH is a sequence of directories separated by colons

Modify it using: PATH=$PATH:/your/directory

if you want to make it permanent you need to put that command into your .bash_profile or .zshrc

alias ll='ls -l'

unalias ll

The shell can redirect standard in, standard out and standard error to and from files. Any command that reads from standard input can read from a file instead with the shells <, > and 2> operator

Redirection of standard input of one command can be redirected to another command using the | operator.

If you want a word contain whitspaced you need to surround it with single or double quotes to make the shell treat it as a unit. Double quotes will result in evaluating the actual content and replacing shell variables with there actual content.

If a character has a special meaning to the shell but you want it used literally, precede the character with a backslash \

The shell allows you to recall previous commands. All commands you are entered are stored inside the command history. Here are some handy command you can use for it

All shells have job control: the ability to run programs in the background (multitasking) und foreground (running as the active process at your shell). Jobs are higher level than processes.

Example:

-rw-r--r--

....