BashShellOptions

Clobber

If option noclobber is set, redirect >filename will not overwrite an existing file. This can be overridden by >| filename.

set -o noclobber # enable noclobber
set +o noclobber # disable noclobber

For those new to BashShell, not that it is a little counterintuitive that -o enables and +o disables. Likely -o came first and then +o is an intuitive opposite to -o, (though I don't know).