Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

Altering File Permissions with chmod

You can use the chmod command to alter a file’s permissions. This command uses various forms of command syntax, including octal or a mnemonic form (such as u, g, o, or a and rwx, and so on) to specify a desired change. You can use the chmod command to add, remove, or modify file or directory permissions to protect, hide, or open up access to a file by other users (except for the root account or a user with super user permission and using sudo, either of which can access any file or directory on a Linux system).

The mnemonic forms of chmod’s options are (when used with a plus character, +, to add, or a minus sign, -, to remove):

• u—Adds or removes user (owner) read, write, or execute permission

• g—Adds or ...