Shell

When is the .profile file loaded?

Once, when you login into your os

When is the .rc file loaded?

Every time you start a new terminal.

What was the default shell in UNIX 7?

The Bourne Shell (sh) created by Stephen Bourne.

Is there only 1 shell?

No, There are a lot of different shells.

Does the Bourne Shell load the .rc file?

No.

What was the replacement of the Bourne Shell (sh)?

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

Name another very popular shell.

zsh (Z Shell)

If you want to add a path to your PATH variable that should be permanent, where to add it?

You need to do it in either the .profile or .rc file, otherwise it will get lost once you restart the terminal.

How do I add an alias?

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

What does the $SHELL command tell you?

The current shell you are using.

How can I check if my default shell is just a symlink to another shell?

Go into the directory of the default shell and run ls -lah. This is often used to symlink sh to bash.

What does the $PWD environment variable stand for?

Print working directory.

How can you create a symlink?

Use the command ln -s FILE DESTINATION.

How can you see all registered shells?

Cat the content of /etc/shells.

How can you get a list of all environment variables?

Use the command export -p.

What does the $ sign in the terminal represent?

The $ sign in the terminal stands for a variable.

How can you use the result of one command inside another?

You can use a variable: echo that is the path for $(which brew)

How can you directly access a binary file from anywhere if its directory is registered in your path?

By simply typing the name of the binary file in the command line.

How can you change the default shell to zsh as example?

chsh -s $(which zsh)

How can you check the directories that are registered in your path?

echo $PATH

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

which brew

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