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Thread: Tid-Bits #3- Setting Permissions

  1. #1

    Tid-Bits #3- Setting Permissions

    Whether you realize it or not, everything you touch, poke, manuver or mangle in linux has a set of "permissions" on it. Permissions, obviously, limit who can use a file/folder, and to what extent they can use a file/folder. As Root, you have access to everything, as well you should. Permissions are the nuts and bolts of who can and can't access something. In summation, Permissions control whether a user can read, write or execute a file, and in all combinations of those. There is another area called "groups". Groups are generally what the user belongs to. Technically, each user is a group. so, if you wanted to share folders with another user, you simply would have to join his/her group. We can set group perms for owner only, group only, or everyone. ok enough, explanations, lets see how to get all of this done.

    We can start with the folowing command in the shell-
    ls -l

    this will list all the files in the current folder and show ALL permissions. also try:

    [greg@Mister_Computer greg]$ ls -l gta3_casino.jpg
    -rw-rw-r-- 1 greg greg 301860 Jun 28 21:25 gta3_casino.jpg

    next, type: groups user name

    this will list the groups you belong to.
    for example:
    [greg@Mister_Computer greg]$ groups greg
    greg : greg users cdrecording

    ok, know that we can see what belongs to who and what they ca do with it, lets check into how we can change these options. the command to change general permissions is "chmod xxx". The three "x's" after the chmod are any number between 0 and 7. those numbers define the permissions for the file. the following is an explanation of the logic in the numbers.

    read write Execute
    0 N N N
    1 N N Y
    2 N Y N
    3 N Y Y
    4 Y N N
    5 Y N Y
    6 Y Y N
    7 Y Y Y

    Better yet, check this out:
    1 = execute only
    2 = write only
    3 = write and execute (1+2)
    4 = read only
    5 = read and execute (4+1)
    6 = read and write (4+2)
    7 = read and write and execute (4+2+1)

    so that is how we adjust general permissions. On to Group Permissions.

    to change Group Permissions, the command is:
    chgrp group file/dir

    There is one other way to set perms, and it is mroe all inclusive. here we go:
    chmod {u/g/o/a} {+/-/=} {r/w/x}
    u = owner/user r = read
    g = group w = write
    o = other x = execute
    a = all users

    for example i can say:
    chmod a+rwx and that would give all users read, write and execute perms.

    chmod u-x would remove the execute perm from a user.

    chmod u=rw sets read and write permission just for the user.

    Lastly, if you want to just point and click, we can cater to that too.
    all you have to do is right click, go to properties(mind you this is in KDE3) and click on the permissions tab at the top. you can check/uncheck boxs in there that will determine perms. At least you know what you are doing behind the scenes now as well. 8)

    Any questions comments or corrections, just speak up. :P

    i wish i could credit the site i got my info from, but it was a page i have had saved for a while???



  2. #2

    Re:Tid-Bits #3- Setting Permissions

    heh, whoops, that looks like more of an OMP than a tid-bit

  3. #3

    Re:Tid-Bits #3- Setting Permissions

    lol, yeah

  4. #4

    Re:Tid-Bits #3- Setting Permissions

    Oddly enough I started working on an OMP for file permissions.

  5. #5

    Re:Tid-Bits #3- Setting Permissions

    OMPs are good for the soul :P , like chicken noodle soup!

  6. #6

    Re:Tid-Bits #3- Setting Permissions

    Poof, you are going to be an OMP, you are one of the lucky ones #3 :P

  7. #7

    Re:Tid-Bits #3- Setting Permissions

    You do realize that your petty OMP will have to compete with mine, right?

  8. #8

    Re:Tid-Bits #3- Setting Permissions

    LOL, I think we will soon find that your OMP will be riding the pine, Ha! ;D : :P

  9. #9

    Re:Tid-Bits #3- Setting Permissions

    now now children.....

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