chmod (change mode) command is used to change the permissions of the files or directories. In unix there is a set of rules for each file which defines who can access that file, and how they can access it. These rules are called file permissions or file modes. The command name chmod stands for "change mode", and it is used to define the way a file can be accessed.
permissions defines the permissions for the owner of the file (the "user"), members of the group who owns the file (the "group"), and anyone else ("others"). The following symbols are used to represent user, group and others.
U: userg: Group
o: Others
The following symbols represent the permissions
r: Read
w: Write
x: Execute
The following symbols represent the paermissions grant or revoke.
+: Additional permissions. Selected permissions are added.
- : Revoke the permissions. Selected permissions are revoked.
=: Specific permissions. Only selected permissions are assigned.
The syntax for chmod command is
The options are
Examples of chmod command
- Give read, write and execute permissions to everyone.
- Remove write permission from group.
