umask problem: wrong permissions for new files
Eliot Moss
moss@cs.umass.edu
Fri Apr 27 09:27:00 GMT 2018
On 4/27/2018 4:54 AM, Andrey Repin wrote:
> Greetings, Ulli Horlacher!
>
>> On Fri 2018-04-20 (07:25), Brian Inglis wrote:
>
>>> Cygwin supports Windows ACLs as POSIX ACLs, which are also supported by
>>> Linux. Use setfacl to set similar default ACLs (DACLs) on a Linux
>>> directory, rerun your test there, and you should see similar results.
>
>> (How) can I completly remove ACLs from the cygwin files and directories?
>
> You CAN, yes.
> However, you will lose any way to access the files, as explained below.
>
>> The standard UNIX permissions are sufficent for my needs and much easier
>> to handle :-}
>
> "Standard POSIX" permissions are insufficient even for most basic operations.
> They survive only because removing them would cause even more harm, than
> letting them sit around.
>
>>> *Never* remove DACLs from any Windows directory which will *ever* be used
>>> with any non-Cygwin Windows program: /undefined behaviour/ will result.
>
>> Uuups... thanks for the warning!
Let me add this ...
What mostly work for me (occasional gotchas) is this:
I am "moss" and I added a group "Cygwin". I have admin permissions under Windows.
A typical file acl for me has owner moss and group Cygwin - sometimes I have to
set these manually, particularly if they are created by a Windows program.
Also, typical acls for files print out as:
# owner: moss
# group: Cygwin
user::rw-
group::rwx #effective:rw-
group:SYSTEM:r-x #effective:r--
group:Cygwin:rwx #effective:rw-
mask:rw-
other:r--
This corresponds to Posix permissions 664. The SYSTEM thing helps insure that
Windows programs, such as my backup program, can read the file.
Here is a typical directory acl:
# owner: moss
# group: Cygwin
# flags: -s-
user::rwx
group::rwx
group:SYSTEM:r-x
group:Cygwin:rwx
mask:rwx
other:r-x
default:user::rwx
default:group::rwx
default:group:SYSTEM:r-x
default:group:Cygwin:rwx
default:mask:rwx
default:other:r-x
This is more complex since it is intended to propagate useful permissions to
files crated within the directory. It is the default entries that help do that.
Note the -s- flag, which encodes the 2000 (set gid) bit of Posix permissions,
enabling propagation of default permissions. This directory's Posix permissions
are 2775. Again, the SYSTEM entries are important for me.
A typical file created by a Windows program (Word, in this case) ends up with
this acl:
# owner: moss
# group: moss
# flags: -s-
user::rwx
group::---
group:SYSTEM:r-x
group:Cygwin:rwx
mask:rwx
other:r-x
The Posix permissions read as 2775 (rwxrwsr-x).
Some people like this way of setting things up, some don't. As they say, YMMV.
Regards - Eliot Moss
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