EF> > if (> /etc/rcorder.cache.tmp) 2>/dev/null; then
EF> I would have expected that to be
EF> if (:> /etc/rcorder.cache.tmp) 2>/dev/null; then
EF> and am suprised the shell accepts redirection on an empty command.
"> foo" is the standard idiom in Bourne-type shells to quickly
truncate a file to zero size, without messing up its ownership
or permissions.
The bloated variant ": > foo" is for old BSD farts like me who still
use the csh/tcsh which both do not accept a bare redirection:
% > foo
Invalid null command.
%
Both tcsh and POSIX sh define ":" as a built-in command, also accepting
(and ignoring) arguments.
The original/NetBSD's csh is a funny case. Neither the man page
nor Bill Joy's "An Introduction to the C shell" mention any ":"
built-in. Tests with "goto ''" make me believe that
:
is actually parsed as a label statement with an empty label by csh,
making ": > foo" work almost by accident.
Martin Neitzel
