Command line environment
The environment of the command line refers to the settings and preferences of the current user. It enables users to set greetings,
alias commands, variables, and much more.
Source Bash Profile
All the commands in ~/.bash_profile are executed with the shell command
source ~/.bash_profile. So when changes are made to ~/.bash_profile, run this command to activate the changes in the current session.
The shell command
alias is used to assign commonly used commands to shortcuts (or aliases). The assigned commonly used command should be wrapped in double quotes.
# The following command creates an alias `pd` for the command `pwd` alias pd="pwd"
history command in Unix Systems
history shell command is used to get a history of commands (also known as “events”) that were executed in the current session. The command also allows us to perform operations on this list of commands that have been executed, such as selecting or manipulating a command in the history.
Variables that can be used across terminal commands are called environment variables. They also hold information about the shell’s environment.
export command makes a given variable available to all child sessions initiated from the current session.
# This command will make the environment variable USER available # to all child sessions with the value "Jane Doe". export USER="Jane Doe"
HOME Environment Variable in Unix Systems
HOME is an environment variable present in command line environments. It is used to get the path to the current user’s home directory. This makes it easy for programs to access the home directory when needed.
# To show the path of the home directory use the following command: echo $HOME
Shell Command env
For Unix-based systems like Mac OS and Linux (not Windows), the shell command
env returns a list of environment variables for the current user.