The chmod Command

We use the chmod command to change the access mode of a file. This command comes in many flavors, but we'll be talking primarily about one of them.

chmod who=permissions filename

This gives “who” the specified permissions for a given filename.


The “who” is a list of letters that specifies whom you’re going to be giving permissions to. These may be specified in any order.

  u   The user who owns the file (this means “you.”)
  g   The group the file belongs to.
  o   The other users
  a   all of the above (an abbreviation for ugo)


Of course, the permissions are the same letters that you see in the directory listing:

  r   Permission to read the file.
  w   Permission to write (or delete) the file.
  x   Permission to execute the file, or, in the case of a directory, search it.

Note: Do not put blanks around the equal sign, or your command will not work!

 << Others’ Permissions Index Some examples >>