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 predetermined value. This value is defined by the file-creation mode mask.
To display the value of this mask enter the command
umask
This will produce something like:
077
Sometimes the 0 (zero) is omitted. The values might be different on your system.
Without the mask the system would create files with permissions set to 666 and directories to 777. 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------)
To change your default access permissions you use the command:
umask nnn
Each "n" is number from 0 to 7