OS X - Create a personal bin directory (~/bin) and run scripts without specifying their full path
You need to add the following to file ~/.profile:

export PATH=/Users/thi/bin:$PATH


Then source ~/.profile

Note, that you may need to create this file, and because it begins with a . it might not be visible in the finder for editing via an application like a text editor.  To list all files including hidden ones, use:

ls -la ~/