[Fwd: User account ( hacked ) of FC6 System]

[Les Mikesell]

edwardspl at ita.org.mo wrote:
>>   
>>>>> chmod g+rwx ( What number of g+rwx, eg : ?77 ) /home/edward
>>>>>         
>>>> You can use the symbolic form literally. I think it's easier to
>>>> understand. Let the computer do the binary/octal math.
>>>> g+rwx means add the read, write, and execute bits for the group.
>>>>       
>>> But I want to know what no of g+rwx...
>>>     
>>
>> The + means it is added to the bits already permitted.  Look at them as
>> groups of 3 bits in binary and take the octal value.
>>
>>  user   group    other
>>  rwx    rwx     rwx
>>
>> You'll start with a home dir having rwx --- ---  so that's 111 000 000
>> binary or 700 octal.
>> Add  the group rwx and you get 111 111 000 or 770 octal
>>   
> So, g+rwx = 770, right ?

No..  Literally it means to add the 2nd 7 (the ---rwx--- positions) to 
whatever was there before.  In the case of a typical home directory it 
will be 770 because the first 7 ( rwx------) was already there.

>>>>> chmod +t ( What number of +t ) /home/edward
>>>>>         
>>
>> That's one more bit to the left, 1 000 000 000  binary, so 1000 octal.
>> Add that to what you have.
>>
>>   
>>>> Same here, you can type it that way and it means add the "sticky" bit.
>>>>       
>>> Also want to know...
>>>     
>>
>> Altogether, the octal value for the mode ends up at 1770.  But, as I
>> said before the computer does a better job of thinking in octal.
>>   
> So, +t = 1770, right ?

Again, that is the case where you already have 770 set, but +t really 
means to add the 1000 bit to whatever was there.  You can also specify 
absolute settings in the symbolic style:
chmod u=rwx,g=rwx,o=t file...
will set 1770 regardless of what is there and is easier to understand.
See 'man chmod' for more details, but it helps to know that the modes 
are simply bits where 1 gives the permission, 0 does not. The values you 
compute in octal show the combinations of the bits but they really each 
only have their own independent meaning so I think the symbolic form 
makes more sense.

-- 
   Les Mikesell
    lesmikesell at gmail.com