变量和注释

Comments are lines that exist in computer programs that are ignored by compilers and interpreters.

# This is a comment

When you reference a variable in bash it is important not to put spaces around the equals sign.

# User variable
name="Cael"
echo "My name is $name"
echo "My name is ${name}_bank"

System variables are mostly in Capitals.

# System variable
echo Our shell name is $BASH
echo Our shell version is $BASH_VERSION
echo Our home directory is $HOME
echo Our current directory is $PWD