Generally I prefer to avoid asking simple questions, but I can't seem to get any information on this one. If I were to write this function, for example:

if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi

what does the '.' in the second line indicate ('.' ~/.bashrc)?

sure its not a mistake? i dont see any reason for it to be there

'.' is equivalent to 'source'. Both are bash builtins, so, check the bash man page to see what 'source' does.

The basic purpose of 'source' is to dump the contents of a shell script on the current shell, instead of spawning a new sub-shell. This is done this way because in bashrc you usually set a number of variables, and setting them into a subshell really makes no sense, since they will go away when the script exits. So, if you want a shell to run on the current shell you 'source' it instead of running it the traditional way.

Eureka!

OK, I get the general idea. Now I just have to read the man for source and learn what sub-shells are. That's easy enough though, I can take it from here. Thank you!