升级除kernel外的rpm: up2date -u
升级包括kernel在内的rpm: up2date -u -f
[root@proxy sysconfig]# up2date -u
There was an SSL error: [('SSL routines', 'SSL3_GET_SERVER_CERTIFICATE', 'certificate verify failed')]
A common cause of this error is the system time being incorrect. Verify that the time on this system is correct.

由于Red Hat Network SSL证书过期，所以应在rhn_register || up2date 之前先执行一行script以更新证书：

[root@proxy sysconfig]# wget -q -O - https://rhn.redhat.com/help/new-cert.sh | /bin/bash

Testing SSL connectivity against https://xmlrpc.rhn.redhat.com/XMLRPC ...
Connectivity OK, test succeeded

The file /usr/share/rhn/RHNS-CA-CERT has been successfully updated.
Please register for updates by running 'rhn_register'.
[root@proxy sysconfig]# rhn_register
出现图形界面，下一步，填写完注册信息，看到Finish，就表示已经注册完成了。

开始使用up2date了：
up2date -l   列出所有需要升级的套件
up2date --showall　<==列出您的版本中，有沒有可以升級的套件
up2date -i packages<==直接升級 packages 那個套件！例如：
up2date -i gdb　<==直接連到 Red Hat 主機升級 gdb 這個套件
up2date -i u　　<==全部的套件升級！等於升級您的 Red Hat ！

[root@proxy /]# rpm -qa | grep httpd
httpd-manual-2.0.40-21
httpd-2.0.40-21
[root@proxy /]# up2date -i httpd

Fetching package list for channel: redhat-linux-i386-9...
########################################

Fetching Obsoletes list for channel: redhat-linux-i386-9...
########################################

Fetching rpm headers...
########################################

The following packages you requested are already updated:
httpd

OK