Red Hat Enterprise Linux 5 Administration Unleashed

594umount command, removing logical volumes from volume groupsumount command, removing logical volumesfrom volume groups, 177unclean match extension (IPTables), 494UNIX, CUPS, 398until loops, 246Update Agent. See YUMupdatesLinux installation sources, 14RHN, 79system groups, 84-85updatingNIS maps from master servers, 262RPM software, 131-132software, YUM, 91-92upgrade command (kickstart), 32upgrades, Linux, 55uptime command, reporting systemprocessors, 412USB devices, listing, 154-156Use MD5 Passwords option (AuthenticationConfiguration tool), 289Use Shadow Passwords option (AuthenticationConfiguration tool), 289User Access tab (NFS Server Configurationgraphical tool), 298user accounts, becoming root users, 110user command (kickstart), 43-44User directive (global configurationdirectives), 331User role (RHN), 81useradd -D command, addingusers, 215useradd commandadding users, 208options list, 208-209userdel command, deleting users, 211usermod command, 209usernames, managing, 217usersgroups/etc/group file, 215group names, 215private user groups, 206managingadding users, 206-208, 215creating users, 216deleting accounts, 218deleting users, 208, 211/etc/group file, 215/etc/passwd file, 214/etc/shadow file, 215listing users, 206managing passwords, 217modifying users, 209, 215password aging, 210structuring /home directory, 218-219UID, 206user groups, 206usernames, 217permissions, ACL, 185effective rights masks, 187enabling, 186modifying, 186-187preserving, 189removing, 189setting default ACL, 188viewing, 186RHNassignments, 81-82granting access, 85roles, 81-82Users view (RHN), 80