yum upgrade、yum update 有区别吗

测试一下所谓yum upgrade于yum update的区别：

基本信息：

--obsoletes:This option only has affect for an update, it enables yum´s obsoletes processing logic. For more information see the update command above.
Configuration Option: obsoletes
upgrade:Is the same as the update command with the --obsoletes flag set. See update for more details.
update:If run without any packages, update will update every currently installed package. If one or more packages or package globs are specified, Yum will only update the listed packages.While updating packages,yum will ensure that all dependencies are satisfied. (See Specifying package names for more information)
If the packages or globs specified match to packages which are not currently installed then update will not install them. update operates on groups, files, provides and filelists just like the "install" command.
If the main obsoletes configure option is true (default) or the --obsoletes flag is present yum will include package obsoletes in its calculations - this makes it better for distro-version changes, for example: upgrading from somelinux 8.0 to somelinux 9.
Note that "update" works on installed packages first, and only if there are no matches does it look for available packages. The difference is most noticeable when you do "update foo-1-2" which will act exactly as "update foo" if foo-1-2 is installed. You can use the "update-to" if you’d prefer that nothing happen in the above case.SourceByrd's Weblog-https://note.t4x.org/basic/upgrade-diff-update/

yum upgrade：

结论:Centos6.4 升级到 Centos6.6 貌似 yum update 和 yum upgrade 均可！SourceByrd's Weblog-https://note.t4x.org/basic/upgrade-diff-update/ SourceByrd's Weblog-https://note.t4x.org/basic/upgrade-diff-update/