Difference between “./”, “.” and “source” in BASH shell or terminal (Linux)

Let’s understand each of these in the context of the sample test.sh file.

Using “./“

The changes made by script gets discarded as soon as scripts end because this runs script by forking a separate process. Example:

./test.sh

Using “.“

The changes made by the script persist till the terminal remains alive because the script gets executed in the same bash process. Example:

. test.sh

Using “source“

source are “.”  are synonyms and the same thing. “.” is the inclusion of POSIX standard. Example:

source test.sh