Unix shell script find out which directory the script file resides?

Question

Basically I need to run the script with paths related to the shell script file location, how can I change the current directory to the same directory as where the script fil

Answer 1

An earlier comment on an answer said it, but it is easy to miss among all the other answers.

When using bash:

echo this file: "$BASH_SOURCE"
echo this dir: "$(dirname "$BASH_SOURCE")"

Bash Reference Manual, 5.2 Bash Variables