The Redhat Linux version is upgraded

Decisively change to centos.,CentOS is a recompiled version of rhel5.,After installation, get a NetEase's yum source rpmfusion source.,yum update can be upgraded.,It's completely free.,There's a lot of software.。

Redhat Enterpries cannot be upgraded without genuine certification unless the kernel is recompiled and its yum removed

It is recommended to install the operating system from the new.,You can't seem to go up this one.。 You may be able to go up, but it will take some effort. It's not easy to get it.,Come up and report the GCC error.,It's obvious that your version is low.。

There has been a gap of 10 years between these two versions of the kernel, big brother, just install the new version of the operating system.

In addition, you don't need to install it so new, just install CentOS 6 directly, don't chase the number 9 anymore, it's already an old thing from nearly 10 years ago.

First of all, I would like to know how you upgraded, e.g. if you upgraded directly with an RPM package, or if you compiled the new version yourself and then added the path to the new version to the system path. According to the content on your **, it only shows that the SSHD service failed to start, but you don't know your upgrade method, it may just be that the SSHD that comes with the system fails to start, but your new version is successfully started. That's why the kind of situation you said came about, and you can see the SSHD process in the background.

If it's an RPM upgrade, this shouldn't happen.

If you are compiling and installing it yourself, then you need to modify the service file of SSHD to change the command startup path to the command path after you compile and install, so that you can use the systemctl command to start the new version of the software.

**Who can read such a small word clearly?

OpenSSH is built with the system.

Generally, it is not necessary, the upgrade can be started with a new version of the CD, and you can install it by selecting the update method.

There's no need to upgrade, unless you're using a package that doesn't support it on your current system.

As long as it does not meet the requirements functionally, it is not recommended to upgrade.

yum -y update

Upgrade all packages, change software settings and system settings, and upgrade the system version kernel to yum -y upgrade

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

Didn't your teacher teach you to choose the most stable version instead of the latest version.