How to run something from the folder the script is in

Lets say I have a script 开发者_Go百科called foo in some folder and a script called bar in the same folder. Say foo looks like this:

./bar

Now if I call ./foo, this will work fine, but if I am in another folder and call somefolder/foo, it will fail.

How can I get this to the point where ./bar is interpreted from the directory that foo is in?

foo could look like this:

cd "$(dirname "$0")"
./bar

Answered pretty exhaustively for bash and other shells in:

Getting the source directory of a Bash script from within