Default umask Setting

When you create a file or directory, it has a default set of permissions. These default permissions are determined by the umask setting in the /etc/profile file, or in your .cshrc or .login file. By default, the system sets the permissions on a text file to 666, which grants read and write permission to user, group, and others, and to 777 on a directory or executable file.

The value assigned by the umask command is subtracted from the default. This process has the effect of denying permissions in the same way that the chmod command grants them. For example, while the chmod 022 command grants write permission to group and others, the umask 022 command denies write permission for group and others.

The following table shows some typical umask settings, and the effect on an executable file.

Table 16–3 umask Settings for Different Security Levels

Level of Security	umask Setting	Permissions Disallowed
Permissive (744)	022	w for group and others
Moderate (740)	027	w for group, rwx for others
Moderate (741)	026	w for group, rw for others
Severe (700)	077	rwx for group and others

For more information on setting the umask value, see the umask(1) man page.