The new directories are created with permissions starting with 8r777 but masked with the permissions of the parent directory according to the formula given in open. This has the effect of limiting the permissions of the newly created directories to those of the parent directory. For example, if the parent directory lacks write permission for group and no permissions for 'other', then so will the newly created directory.
A warning message is generated if a directory of the specified name already exists. Execution continues for the remaining names in the argument list, if any.
chmod - change file mode (permissions)|
rm - remove file(s) |
open, create - open/create a file for reading or writing in Chapter 8|