Example
Sourcing a file is different from execution, in that all commands are evaluated within the context of the current bash session - this means that any variables, function, or aliases defined will persist throughout your session.
Create the file you wish to source sourceme.sh
#!/bin/bash
export A="hello_world"
alias sayHi="echo Hi"
sayHello() {
echo Hello
}
From your session, source the file
$ source sourceme.sh
From hencefourth, you have all the resources of the sourced file available
$ echo $A
hello_world
$ sayHi
Hi
$ sayHello
Hello
Note that the command . is synonymous to source, such that you can simply use
$ . sourceme.sh
