You will need to understand how to set file access permissions numerically before reading this section. Every time you create a file or a directory, its access permissions are set to a predetermined value. ... The values in the mask are subtracted from these values to give a default value for access permissions for the files and directories created by you. For example: 777 (system value for directories) -077 (value of the umask) --- 700 (default access permission of rwx------) . ...