The
bane of many a
computer user. Some programs are
sensitive to
whitespace. Normally inconvenient, but sometimes a
catastrophe. Like when you inadvertantly leave whitespace at the
end of a
line. Unless you set up some special
editing modes, this whitespace is
invisible, yet your file won't work.
An example of a horrible place for trailing whitespace is the end of a Perl here document. If you have something like this:
$x = <<END;
This is the first line
This is the second
END
(highlight the "END" line to see what's going on!), Perl won't recognise the
terminator!
This can waste a significant amount of time out of your life.