Differences between yum-y upgrade and yum-y update

Test yum-y upgrade and yum-y update respectively.

Before upgrade

System Version: CentOS5.5

Kernel version: 2.6.18-194. el5

Simple configuration file modification before Upgrade

After yum-y upgrade is upgraded

System Version: centos5.7

Kernel version: 2.6.18-194. el5

System and software configurations are not modified

After yum-y update is upgraded

System Version: centos5.7

Kernel version: 2.6.18-238. el5

System and software configuration file updates

Conclusion:

Yum-y update

Upgrade all packages, change software and system settings, and upgrade the system version and kernel.

Yum-y upgrade

Upgrade all packages without changing the software and system settings. upgrade the system version without changing the kernel.

Recommended reading:

Configure the epel yum Source

RedHat local yum source configuration

RedHat Linux local yum source configuration

RedHat 6.2 modify yum source in Linux use CentOS source for free