source (command)

source is a Unix command that evaluates the file following the command, as a list of commands, executed in the current context.

Frequently the "current context" is a terminal window into which the user is typing commands during an interactive session. The source command can be abbreviated as just a dot.

Some bash scripts should be run using the source your-script syntax, e.g., if they contain a change directory (cd) command and the user intends that he be left in that directory after the script is complete, or the script file does not have the "execute" permission.