Why do you need ./ (dot-slash) before executable or script name to run it in bash?

Question

When running scripts in bash, I have to write ./ in the beginning:

$ ./manage.py syncdb

If I don\'t, I get an error message:

Answer 1

This question already has some awesome answers, but I wanted to add that, if your executable is on the PATH, and you get very different outputs when you run

./executable

to the ones you get if you run

executable

(let's say you run into error messages with the one and not the other), then the problem could be that you have two different versions of the executable on your machine: one on the path, and the other not.

Check this by running

which executable

and

whereis executable

It fixed my issues...I had three versions of the executable, only one of which was compiled correctly for the environment.