8.4 Permissions

The main command used to manage permissions is chmod. There are quite a few ways to use chmod. For beginners, it is best to use the symbolic method. The following is an example to remove world read permission from a file called xyz:

chmod o-r xyz

What does o-r mean? It means the following:

• o: others
• -: remove
• r: read permission

In general, the permission change symbol is as follows:

• u for user, g for group and o for others
• + for add, - for remove and = ``change to''
• r for read, w for write, x for execute

There can be multiple Permission change symbols separated by commas (but no space in between).

Of course, the chmod is more capable than this. Please refer to the man page of chmod for more details.