edwardspl@xxxxxxxxxx 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@xxxxxxxxx
