You use the dot command:

Code:

. filename

to have the current shell execute the commands in filename in your current shell execution environment. This works as long as filename is readable by you. Since the commands in filename were executed in the current shell execution environment, any variables set while it was running will be available for you to use in subsequent commands.

You use the command:

Code:

filename

(without the .) to run the commands in filename in a separate shell execution environment . When the commands in filename are done, that separate shell execution environment is deleted and anything that commands in filename did that did not change other files or were not written somewhere disappear. This doesn't work unless you have permission to execute filename and filename is on your search path for commands (as specified by the PATH environment variable).

But, it is also possible for a shell script to set up an environment and invoke an interactive database session. That script will not end until the interactive session is terminated by logging out of the database session.

All of the above are possible whether or not filename's first character is a <period>. The best way to figure out what a script might do is usually to read the file and look at the manual pages for your system to figure out what the commands in that file are doing.