On 27/01/2023 20:52, Mike Frysinger wrote:
i've been under the mistaken assumption that the -n/--no-clobber option exits
non-zero when the target exists, but someone pointed out to me recently that
it silently ignores existing files. can we get a setting to control this ?
Yes --no-clobber={skip (default), fail} would have some value.
Especially for handling multiple files.
basically i've been writing things like:
if ! cp -n foo bar; then
... error out because bar already exists, or otherwise failed ...
fi
when really i need to write:
if [ -e bar ] || ! cp foo bar; then
... error out ...
fi
The above is racy if the file is created between the test and the cp.
I suppose you could leverage the shell to create the file atomically like:
cp-n-fail() {
(set -C && cat < "$1" > "$2")
}
cp-a-n-fail() {
cp-n-fail "$1" "$2" &&
cp -a --attributes-only "$1" "$2"
}
But yes hack, only handles single files, doesn't handle sparseness, ...
cheers,
Pádraig
