chmod is an abbreviation for change mode, the command is used to change access rights of files and directories.

Permissions are assigned to the three classes of users associated with each file as file's owner, group members and others:

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

• the user can read, write, and execute it,
• members of your group can read and execute it,
• others can only read it.

-The letters u, g, and o represent user, group and others.

-The equal sign (=) means set the permission.

-The letters r, w and x stand for read, write and execute.