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Re: File permissions and ownership changes between Unix and Cygwin
- From: Brian Dessent <brian at dessent dot net>
- To: cygwin at cygwin dot com
- Date: Sat, 17 Dec 2005 16:38:06 -0800
- Subject: Re: File permissions and ownership changes between Unix and Cygwin
- References: <email@example.com>
- Reply-to: cygwin at cygwin dot com
surendar jeyadev wrote:
> I understand that this is something to do with
> but I was wondering if there is a Cygwin trick that I
> am missing. I would like burn disks so that they have
> the right permissions and ownerships when used on a
> Unix/Linux machine. In particualar, I want 'r--r--r--'
> for the permissions and 'root' for owner and group.
As far as I understand it, the basic ISO9660 format does not have any
fields to store file attributes such as owner or permissions. So on
mounting such a disc, Windows and/or Cygwin will have to synthesize
these fields, which is probably why they are not set as you want.
To enable storing of these attributes you need to use the Rock Ridge
extension. When creating your image you will have to make sure that you
enable these extensions (-R, -r, etc.) Although from the man page it
looks like the author may be somewhat biased against win32:
-R Generate SUSP and RR records using the Rock Ridge proto-
col to further describe the files on the iso9660
-r This is like the -R option, but file ownership and modes
are set to more useful values. The uid and gid are set
to zero, because they are usually only useful on the
author's system, and not useful to the client. All the
file read bits are set true, so that files and directo-
ries are globally readable on the client. If any exe-
cute bit is set for a file, set all of the execute bits,
so that executables are globally executable on the
client. If any search bit is set for a directory, set
all of the search bits, so that directories are globally
searchable on the client. All write bits are cleared,
because the CD-Rom will be mounted read-only in any
case. If any of the special mode bits are set, clear
them, because file locks are not useful on a read-only
file system, and set-id bits are not desirable for uid 0
or gid 0. When used on Win32, the execute bit is set on
all files. This is a result of the lack of file permis-
sions on Win32 and the Cygwin POSIX emulation layer.
See also -uid -gid, -dir-mode, -file-mode and
I'm not sure what "This is a result of the lack of file permissions on
Win32 and the Cygwin POSIX emulation layer" but it seems like some
pretty thick ignorance, since that's the entire point of Cygwin.
You should post your question on the cdrtools list or forum, since this
is not a cygwin package.
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