I think the  -1 is not needed. At least the gnu coreutils and the freebsd versions of ls default to using multi-column output only when the output goes to a terminal, and single-column output otherwise. In fact, even POSIX mandates that the single-column output is the default when the output is not to a terminal, and leaves the other case implementation-defined. (This is of course unless you alias ls to something stupid, which many people and even distributions do, but that's their fault, and in that case \ls is still shorter than ls -1.)