Unix access privileges
Download
1 / 12

Unix Access Privileges - PowerPoint PPT Presentation


  • 99 Views
  • Uploaded on

Unix Access Privileges. Who can access what files and how. Access privileges. All unix files have privileges associated with them. These privileges determine who can access the file. These privileges determine how people can access the file. Viewing access privileges.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Unix Access Privileges' - ulf


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Unix access privileges

Unix Access Privileges

Who can access what files and how.


Access privileges
Access privileges

  • All unix files have privileges associated with them.

  • These privileges determine who can access the file.

  • These privileges determine how people can access the file.


Viewing access privileges
Viewing access privileges

  • Use the ls -l command.

drwx------ 2 jimd 8192 Jul 12 12:26 nsmail/

-rw-r--r-- 1 jimd 945 Mar 15 16:01 old.cshrc

-rwxrwxrwx 1 jimd 168 Jan 13 1998 file.exe

-rw-rw-rw- 1 nobody 382 Nov 18 1998 old.profile

-rw------- 1 jimd 652 Jul 12 12:16 old.xsession

drwx------ 2 jimd 8192 Jun 23 13:21 thesis/

-rw-r--r-- 1 jimd 1186776 Jul 13 15:07 win32tutorial.ps


Types of file access
Types of file access

  • Read — person can look at the contents of the file.

  • Write — person can change the file.

  • Execute — person can execute the file (applies only to directories and program).


Types of users
Types of users

  • User/owner -- the person who owns/created the file.

  • Group — Unix allows for the creation of groups.

  • Others/world -- everyone else in the world that has access to that computer.


To change permissions
To change permissions

chmod — changes the access mode of a file.

Two methods exist

symbolic

absolute


Chmod absolute
chmod - absolute

  • Absolute - you specify a numeric equivalent for a set of permissions.

  • You specify all permissions at once.

  • This is not for the faint of heart.


Chmod absolute1
chmod - absolute

  • chmod [xxx] [file]

  • Where each x is some number from 0 - 7.

  • Each number specifies a level of privileges for a specific group.


Chmod absolute2
chmod - absolute

  • e.g.,

chmod 644 moocow.txt

User permission

World permission

Group permission


Chmod absolute3
chmod - absolute

  • Permissions: rwx

    • Read = 4 - 100

    • Write = 2 - 010

    • Execute = 1 - 001

  • Set permissions by adding the values of all the permissions you wish to set.


Chmod examples
chmod - examples

  • To give yourself read & write permission and no permission to anyone else:

    • chmod 600 foobar.txt

  • To give yourself read & write permission and everyone else read permission only:

    • chmod 644 index.html

  • To give yourself full access to a directory, and everyone else read & execute permission only:

    • chmod 755 homeDirectory


Reading
Reading

  • Appendix D.


ad