An idea on extending the "Package users" approach

Angel Tsankov fn42551 at
Tue Jan 6 14:07:10 PST 2009

Tushar Teredesai wrote:
> If you do a chmod root /usr/bin/crontab, then after the operation you
> do not know which package /usr/bin/crontab just by doing a ls -l
> /usr/bin/crontab. See the TIP at the end of Section 4.4 of the
> hint[1].

'ls -l' shows a file's owner and group. In the example you give, the owner 
is root and the group is the package name without version information. Note, 
that what you get when you setuid is exactly the same as if you had followed 
the user name=group name approach. In the case of setgid the results are 
slightly different -- you lose the package name (since the group is changed) 
but you have the package name plus package version (in the owner's name).

>>> Lot of file clashes between users. Say you install foo-1.0 and then
>>> upgrade to foo-1.2. Generally, there will be lot of files that will
>>> be common to both foo-1.0 and foo-1.2. User foo-1.2 cannot update
>>> these files belonging to foo-1.0 without manual intervention.
>> Upgrading foo-1.0 to foo-1.2 should go without problem as both users
>> foo-1.0 and foo-1.2 belong to the same group -- foo.
> foo-1.0 and foo-1.2 are separate users. foo-1.2 will not be able to
> overwrite files belonging to foo-1.0 unless you modify the
> permissions. See Section 4.6 of the hint[1].
Are you saying that users belonging to group G cannot change a file whose 
group is G?


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