‘chmod’ — For Linux/Unix users

‘chmod’ command is used to change permissions of a file/directory by Linux/Unix users.

This command can be used in 2 different forms.

1. Symbolic permission notation

chmod who=permissions filename

‘who’ refers to :

u: user who owns the file , g : group that file belongs to , o: other users ,

a: all the above

‘permissions’ refers to:

r: read , w: write , x: execute

So, an example ‘chmod’ command to give,

• read,write and execute permissions to a user
• read and execute permissions to the group
• read permissions to other users

will be as follows.

chmod u=rwx,g=rx,o=r myfile

2. Octal permission notation

chmod octal-number filename

The ‘octal-number’ above is the representation of permissions in a numerical manner.

When taking user, group, other from the representation in the symbolic notation and considering the same example,

u : r w x : 111 : 7

g : r — x : 101: 5

o : r — — :100:4

chmod 754 myfile

References:

Tutorial for chmod

Linux and Unix chmod command help and examples