chmod

CHMOD is used to change permissions of a file.

  PERMISSION      COMMAND   



   U   G   W

  rwx rwx rwx     chmod 777 filename      

  rwx rwx r-x     chmod 775 filename

  rwx r-x r-x     chmod 755 filename


  rw- rw- r--     chmod 664 filename

  rw- r-- r--     chmod 644 filename



  U = User 

  G = Group 

  W = World




  r = Readable

  w = writable

  x = executable 

  - = no permission

Here is another way of looking at it:

Permissions:

400     read by owner

040     read by group

004     read by anybody (other)

200     write by owner

020     write by group

002     write by anybody

100     execute by owner

010     execute by group

001     execute by anybody

To get a combination, just add them up. For example, to get read, write, execute by owner,
read, execute, by group, and execute by anybody, you would add 400+200+100+040+010+001 to give 751.