# Description
This PR adds possibility to preserve/strip attributes from files when
using `cp` (via uu_cp::Attributes). To achieve this a single `--preserve
<list of attributes>` flag is added. This is different from how
coreutils and uutils cp function, but I believe this is better for
nushell.
Coreutils cp has three options `-p`, `--preserve` and `--no-presevce`.
The logic of these two options is not straightforward. As far as I
understand it is:
1. By default only mode attributes are preserved
2. `--preserve` option adds to default preserved attributes specified
ones (e.g. `--preserve=xattr,timestamps` will preserve mode, timestamps
and xattr)
3. `-p` is the same as `--preserve=mode,ownership,timestamps`
4. `--no-preserve` option rejects specified attributes (having priority
over `--preserve`)
However (in my opinion) the `--no-preserve` option is not needed,
because its only use seems to be rejecting attributes preserved by
default. But there is no need for this in nushell, because `--preserve`
can be specified with empty list as argument (whereas coreutils cp will
display a `cp: ambiguous argument ‘’ for ‘--preserve’` error if
`--preserve` is used with empty string as argument).
So to simplify this command is suggest (and implemented) only the
`--preserve` with the following logic:
1. By default mode attribute is preserved (as in coreutils cp)
2. `--preserve [ ... ]` will overwrite default with whatever is
specified in list (empty list meaning preserve nothing)
This way cp without `--preserve` behaves the same as coreutils `cp`, but
instead of using combinations of `--preserve` and `--no-preserve` one
needs to use `--preserve [ ... ]` with all attributes specified
explicitly. This seems more user-friendly to me as it does not require
remembering what the attributes preserved by default are and rejecting
them manually. However I see the possible problem with behavior
different from coreutils implementation, so some feedback is
apprecieated!
# User-Facing Changes
Users can now preserve or reject file attributes when using `cp`
# Tests + Formatting
Added tests manipulating mode and timestamps attributes.
387c5462e9