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From: Rainer Weikusat <rweikusat@mssgmbh.com>
Newsgroups: comp.os.linux.development.system
Subject: Re: need to block changes to a file
Date: Wed, 13 Apr 2011 11:16:31 +0100
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zix <zixenus@gmail.com> writes:
>                         I have a file which I want to block any
> changes onto it. How may I accomplish that in kernel space through a
> module?  lets for example, I have some data in /var/carddetails.txt,
> which I dont want any user to not to delete that. He should be able to
> read/write, but not delete, move etc. Can anybody suggest me ways to
> do in linux?

Provided that append-only write access was ok for you and you are
using a filesystem which supports this, you could set the 'append
only' filesystem attribute for it. The userspace tools for these
attributes are lsattr and chattr. Judging from strace output, this is
implemtented via ioctl.