== What is a script language on Unix

There's a lot of argument in general about what is (merely) a 'scripting
language' and what is a fully fledged programming language, deserving
to hold its head up high besides grown up languages like C, Java, and
Pascal.

Unix is a simpler place, because it has a simple and very clear
definition of what is a script versus what is a program. To wit: if the
kernel can directly _exec()_ you in place as is, you are a program. If
not, you are a script (sometimes called an 'interpreter script') and
actually get processed by your interpreter, not the kernel.

(Note that in-place execution doesn't preclude the use of a helper;
almost every program you run on a modern Unix requires the help of the
dynamic loader, which is *not* part of each executable.)

While technical and somewhat picky, this distinction is important. Among
other issues, there are a number of places where a program can be used
that a script cannot be.

As an immediate corollary, on Unix a language that cannot be used to
make programs is a script language, and there are some things that
programs written in that language will never be able to do directly.
Note that this says nothing about their [[suitability for serious
jobs ../python/IndustrialPython]].

(While scripts usually start with '_#! <interpreter>_', some Unixes
have ways to run scripts without that; Linux has [[binfmt_misc
http://en.wikipedia.org/wiki/Binfmt_misc]], for example.)