source

Load variables and functions from a file into the current shell

source file (or . file) runs the file in the current shell. Environment variables set in the file become available immediately: source .env loads all variables.

Example

$ source /etc/environment
$ echo $JAVA_HOME
/usr/lib/jvm/java-17-openjdk-amd64

Tip: Type it yourself in the terminal below - reading is not the same as doing.