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Re: umask not working?




On 3/21/2018 6:36 AM, David Allsopp wrote:
Ken Brown
On 3/19/2018 8:48 AM, David Allsopp wrote:
Is this expected behaviour:

OPAM+DRA@OPAM ~
$ uname -a ; umask ; touch /tmp/foo ; ls -l /tmp/foo ; mkdir /tmp/bar
; touch /tmp/bar/foo ; ls -l /tmp/bar/foo CYGWIN_NT-6.1-WOW OPAM
2.10.0(0.325/5/3) 2018-02-02 15:21 i686 Cygwin
0022
-rw-r--r-- 1 OPAM+DRA OPAM+None 0 Mar 19 13:44 /tmp/foo
-rw-rw-r--+ 1 OPAM+DRA OPAM+None 0 Mar 19 13:44 /tmp/bar/foo

Why does the file /tmp/bar/foo get g+w when /tmp/foo doesn't - I'm not
sure what to look at on my system to diagnose what I may have
inadvertently tweaked. The directory itself is:

drwxr-xr-x+ 1 OPAM+DRA OPAM+None 0 Mar 19 13:44 /tmp/bar

See if this helps:

    https://cygwin.com/faq/faq.html#faq.using.same-with-permissions

Thanks for the pointer. I wonder from it if this could be to do with the Cygwin installation being old (but upgraded). I tried on the same machine creating another installation to C:\cygwin2 (which behaves as Roger Wells noted) and then ran getfacl /tmp on each:

Old installation:

# file: /tmp
# owner: OPAM+DRA-Admin
# group: OPAM+None
user::rwx
user:OPAM+DRA:rwx
group::r-x
mask:rwx
other:r-x
default:user::rwx
default:user:OPAM+DRA:rwx
default:group::r-x
default:mask:rwx
default:other:r-x

Fresh installation:

# file: /tmp
# owner: OPAM+DRA-Admin
# group: OPAM+None
# flags: --t
user::rwx
group::rwx
other:rwx
default:user::rwx
default:group::r-x
default:other:r-x

I expect that the extra OPAM+DRA:rwx on the old installation was manually added by me, years ago. What are the "mask" entries all about?

The default:mask entry seems to be the crucial one, as if I do setfacl default:mask:rwx /tmp on the fresh installation, then I get the same behaviour as on the old installation.

However, I'm struggling to find references for either what these mask entries are, or how they ever appeared?

If you search the web for "Posix acl mask" you'll find lots of information. Here's one that seems pretty good:

  https://cs.unc.edu/help-article/posix-acls-in-linux/

Ken


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