[prog] assigning variables in sh

[Peter Samuelson]

[Almut Behrens]
> and there should be whitepace around the test brackets, i.e. "while [
> $LINE ]; do", not "[$LINE]".

That's a bad habit to get into, and it might be non-portable as well.
What you should do is quote the $LINE variable:

  while [ "$LINE" ]; do

It's a bad habit because, in many situations, you can't be sure that
your input will not have special characters like spaces.  if $LINE has
a space in it, you'll get a syntax error or worse, depending on the
shell.  Perhaps *this* time you can be sure that $LINE won't have
spaces in it, but I'm talking in general.

The reason the original might also be non-portable is that if $LINE
happens to be empty, the expression will expand to "while [ ]; do"
which might throw a syntax error with some shells.  I note that the
bash builtin test, and the test in GNU coreutils, do not spew such a
message - but I could have sworn that some version of Unix does.

Peter