To install Fedora Media Writer on Red Hat Enterprise Linux, use the pre-built Flatpak package. You can obtain the package from the official Flatpak repository http://Flathub.org at https://flathub.org/apps/details/org.fedoraproject.MediaWriter

Connect the USB flash drive to the system.

Open Fedora Media Writer.

From the main window, click Custom Image and select the previously downloaded Red Hat Enterprise Linux ISO image.

From Write Custom Image window, select the drive that you want to use.

Click Write to disk. The boot media creation process starts. Do not unplug the drive until the operation completes. The operation may take several minutes, depending on the size of the ISO image, and the write speed of the USB drive.

When the operation completes, unmount the USB drive. The USB drive is now ready to be used as a boot device.

补充：

如果你的服务器上本来有一个现成的系统，需要重装覆写，如果磁盘空间不够，在进入图形化界面后配置系统那里选择Custom那里，可以看到一个+/-号，就可以把原来的系统删除，然后有一个automatic的配置给你配置系统分区等。

后面就等着装好就完事了。

如果你实在头铁，十分想选择ultraiso作为写入U盘的软件，最好保证安装时有网络连接，刚开始我就用的ultraiso，下载的BOOT iso，跟着网上教程也能进入图形化安装界面，但是因为没有网络连接，因而卡死在那里无解了，如果有网络可能可以，但不保证一定没问题。

这里提供一下我用ultraiso写入U盘进行安装的过程中，遇到坑后提供了解决办法的教程链接，节省大家时间

1.redhat，Linux用U盘安装主要步骤及路上遇到的坑_中山厨子的博客-CSDN博客

2.U盘安装 Redhat Enterprise Linux ( RHEL ) 6.10

3.u盘安装redhat8 – CSDN