Summary

In this chapter, we examined the basics of how users and groups are managed in Red Hat Linux. We began with the configuration files. While /etc/passwd and /etc/ group contain basic information about users and groups, /etc/shadow and /etc/gshadow include encrypted passwords and password age parameters in more secure files. New users are assigned a home directory with a copy of the files in /etc/skel , based on the parameters shown in /etc/login.defs .

You can create users and groups directly, by editing the appropriate configuration files. You can create them more efficiently with commands such as useradd and groupadd . Users and groups can be deleted with the nearly parallel userdel and groupdel commands. And you can manage how user passwords are regulated with the chage command.

This system of users, groups, and associated commands is known as the Shadow Password Suite. With the appropriate strong passwords, this suite can improve the security of your user and group accounts. The pwconv and grpconv commands convert /etc/passwd and /etc/group to conform to this suite. The pwunconv and grpunconv commands reverse this process.

You can manage the demands of your users with quotas. Linux quotas can limit users by inodes or by the space their files occupy on a specific partition. Quotas are easily configurable once you ve modified /etc/fstab to incorporate quotas on desired filesystems. And once they re configured, Red Hat Linux automatically activates your quotas when it boots.

Finally, the Red Hat User Private Group scheme provides additional security by isolating every user in his or her own unique individual group. However, you can still organize users in a common group with a shared directory.

In the next chapter , you ll learn all about the Red Hat way of managing packages with the Red Hat Package Manager. This system has been so successful that it has been adapted by a number of other competitive Linux distributions.