Shell

$SHELL tells you the current shell you are using

To find if the default location is just a symlink, go the directory containing the shell and run ls -lah to see if your shell is just a symlink to another shell, very common for sh → bash

To see the working directory, you can use the environment variable $PWD which stands for print working directory

To create a symlink, use ln -s FILE DESTINATION

If you want to see all registered shells (important for using another default shell), you can cat the content of /etc/shells

To get a list of all environment variables, use export -p

The $ sign in the terminal stands for a variable, as example if you want to write the following in the terminal: echo that is the path for brew which brew will not work because which brew is part of the command now but with the use of a variable: echo that is the path for $(which brew) it will work

To change the default shell to zsh as example. Use chsh -s $(which zsh)

To check the directories that are registered in your path, use echo $PATH

If a directory containing a binary file is registered in your path, you can directly access it from everywhere

An alternative to see the location of a command: command -v brew is which brew

TODO

The .profile file is loaded once you login in the system

The .rc file is loaded on every new terminal

There are a lot of different shells. The Bourne Shell (sh) created by Stephen Bourne was the default shell in UNIX 7.

The Bourne Shell does not load the .rc file

The Bourne shell is mostly dead by now and was replaced with bash (Bourne Again Shell) or on newer linux versions, with dash

Another very popular shell is zsh (Z Shell)

If you want to add a path to your PATH variable you need to do it in either the .profile or .rc file, otherwise it will get lost once you restart the terminal

To add a new alisas, go into your .rc file and add it with alias aliasname=command