Folder permissions with cp --parents doesn't allow to copy another file

Question

Scenario: with a script run by a normal user I want to copy several files, and replicate the dir structure. For example:

cp --parents /lib/libacl.so /tmp/my_root/
cp --parents /lib/libc.so.6 /tmp/my_root/

Expected result: first cp, creates /tmp/my_root/lib and puts libacl.so in there. Second cp puts libc.so.6 in /tmp/my_root/lib.

The problem is that the first cp creates /tmp/my_root/lib with the following permissions: dr-xr-xr-x., so the second cp fails with Permission denied.

Of course, if I run the script as root everything works fine.

One solution could be create the dir first and then copy the file, so the dir will have the proper permissions, but I was wondering if there was a better way of doing this, maybe some flag of cp? I checked the man but didn't find anything.

Answer 1

I cannot see a solution with cp. You can use rsync to do the same sort of copies, and it also creates a non-writeable lib dir, but it is capable of then adding new files to the dir. Your commands become:

rsync -LR /lib/libacl.so /tmp/my_root/
rsync -LR /lib/libc.so.6 /tmp/my_root/

The -R preserves the directory structure. I added -L so that symbolic links are followed, as that seems to be what cp does, though usually this is not what is wanted. You can add -a to preserve permissions and timestamps (and owner/group if root).

rsync is often used to copy files over the network, but it is a very versatile command.

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If you dont have rsync, some other commands which copy files, but create a writeable dir, are tar and cpio:

tar cf - /lib/libc.so.6 | tar -C /tmp/my_root/ -xf -

Or use chf to follow links. For cpio:

ls /lib/libc.so.6 | cpio -pd /tmp/my_root/

with -L to follow links.