LINUX_source

Be careful! ./ and source are not quite the same.

• ./script runs the script as an executable file, launching a new shell to run it
• source script reads and executes commands from filename in the current shellenvironment

Note: ./script is not . script, but . script == source script

http://askubuntu.com/questions/182012/is-there-a-difference-between-and-source-in-bash-after-all?lq=1

help doesn‘t work everywhere (atleast in zsh). type does

help {builtin-name}