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How can I make a write-only view of a folder?

rated 0 times [ 1] [ 0] / answers: 1 / hits: 9294 / 3 Years ago, fri, june 25, 2021, 1:24:08

I want to have a place on the filesystem that presents a write-only "view" of another folder that I have read-write access to.

I'm picturing something that's similar in behavior to an FTP drop box, where files can be copied into it but not read out of it, e.g.:

$ ls read-write-view/ write-only-view/

read-write-view/:

a  b  c



write-only-view/:



$ cp d write-only-view/

$ ls read-write-view/ write-only-view/

read-write-view/:

a  b  c  d



write-only-view/:

It's important that this works as in the example — the contents are still visible when accessed through read-write-view/, and both "views" are functional for a single user.

How can I set something like this up? Some clever arrangement of symbolic links, perhaps? Or an unusual configuration of a bind mount?

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answered 3 Years ago doredtness · Accepted Answer

Use bindfs, which is designed to "mount a directory to another location and alter permission bits."

Start with a normal folder that has both read and write access:

$ mkdir read-write-view && touch read-write-view/{a,b,c}

$ ls read-write-view

a  b  c

Use bindfs to mount the folder without read access:

$ mkdir write-only-view

$ sudo bindfs --perms=a-r read-write-view write-only-view

Verify that only the contents of the original folder can be listed:

$ ls read-write-view write-only-view

read-write-view:

a  b  c

ls: cannot open directory write-only-view: Permission denied

Verify that the original folder can be written to through the mount:

$ echo 'Can you read this?' > write-only-view/d

$ cat read-write-view/d

Can you read this?

Verify that files cannot be read through the mount:

$ cat write-only-view/d

cat: write-only-view/d: Permission denied