Environment variables are dynamic named values stored within the Linux system that are used by applications and processes to define the behavior of the environment. They can affect the ongoing processes or programs executed in the environment and allow you to customize how specific applications and services behave with the system. Each variable contains a name and an associated value, and they can be accessed, modified, and retrieved through the shell, which is a command-line interface that interprets and executes commands entered by the user.
Some key points to keep in mind when working with Linux environment variables are:
- Environment variables follow a naming convention where the name is in UPPER CASE, and the values are case-sensitive.
- The scope of an environment variable in Linux can be global or local. A globally scoped environment variable that is defined in a terminal can be accessed from anywhere in that particular environment that exists in the terminal.
- Environment variables can be useful when you want to override default settings or manage new settings that your system has no reason to create on its own.
To list the environment variables in Linux, you can use the env command, which displays all the environment variables defined for a current session. To print the value of a specific environment variable, you can use either the printenv VARIABLE_NAME or echo $varname command. To define an environment variable, you can use the export VARIABLE_NAME=value command.
Overall, environment variables are a key aspect of Linux system administration and provide engineers with a powerful tool for customizing systems.
