Details on script interpreter invocation - that is, the shebang (#!) line. And the list also reveals a problem with Linux: the path of an interpreter in the #! line is ignored. Classic example: a Python 2.2 installation in /usr/bin, another in /opt/pyds/bin. Now a script is supposed to run with /opt/pyds/bin/python - but if you enter that in the #! line, Linux ignores the path and takes the installation in /usr/bin anyway, and thus the wrong libraries. ! is a nasty hack that sometimes does what you expect. Sometimes. But not always. And certainly not more often than not.