U command, vi text editor,
321
UDP (User Datagram Protocol), TCP/IP and,
154
UID field, /etc/passwd file,
357
umask command, default file permissions, setting,
664-665
uname (GNU shell utility), description,
230
unauthorized access (security threats),
650
unexpand (GNU text utility),
237
Unix-Internet-Fundamentals-HOWTO file,
198
unmount command, CD-ROMs,
132
updates, operating system, security considerations,
696-697
upgrade option, kickstart,
70
upgrades
security considerations,
653
system administration and,
13,
350
upgrading
Red Hat Network, registering with,
618-619
URLs (Uniform Resource Locators)
USB-Digital-Camera-HOWTO file,
198
user ID mapping options (/etc/exports file),
542
useradd command, user accounts,
45
User-Authentication-HOWTO file,
198
/user/bin/switchdesk utility, switching from GNOME to KDE,
266
username field, /etc/passwd file,
357
users (GNU shell utility), description,
230
UTC (Universal Coordinated Time),
45
utilities
redhat-config-xfree86,
86-90
stylesheets
system administration and,
350
UUCP (UNIX-to-UNIX Copy Protocol), newsgroups and,
476