The key to installing CentOS 7, 8 or 9 is to create a bootable USB drive and set up a BIOS. 1. Download the appropriate ISO image, CentOS 7 recommends DVD ISO, 8 and 9 recommends Minimal or Boot ISO, pay attention to selecting the correct architecture (x86_64 or aarch64); 2. Windows users use Rufus to write ISO to the USB disk, select GPT partition and FAT32 file system, and Mac/Linux users need to carefully confirm the device path when writing using the dd command; 3. Enter the BIOS settings to boot from the USB disk, and enter the boot menu and enter the boot menu and adjust the USB device to the first startup item; 4. During the installation process, select the language, focus on configuring disk partitions (automatic partitioning or customization is recommended), network settings (default DHCP), set the root password and create ordinary users, and select the software installation type according to your needs (Minimal is suitable for servers, and GUI is suitable for desktop environments). Although the entire process has many steps, the operation is not complicated, and the key lies in the detailed processing.

Installing CentOS 7, 8 or 9 is actually not difficult, as long as you have a prepared USB boot disk. The key is to create a bootable USB drive and set it to boot from the USB drive in the BIOS. The entire process includes downloading images, writing to USB flash drives, setting up BIOS and formal installation.

Prepare CentOS image files

First you need to download the appropriate ISO file from the official website or mirror site. DVD ISO is recommended for CentOS 7, while Minimal or Boot ISO is recommended for CentOS 8 and 9 (small size, suitable for network installation).
Pay attention to the system architecture when choosing: Currently, most of them are x86_64. If you are an ARM platform (such as Raspberry Pi), you need to choose aarch64 version.
The download address can be considered as an official source or domestic mirroring site, such as Alibaba Cloud, Tsinghua Source, etc., which is much faster.

Create a bootable USB installation disk

Windows users often use Rufus to write ISO to USB drive. After opening the software:

• Select your USB drive
• Select "ISO Image" to start the type, and then load the CentOS ISO you downloaded
• It is recommended to select GPT for partition type (if the motherboard supports UEFI)
• The file system usually defaults to FAT32.

Mac or Linux users can use the dd command, but before operation, be sure to confirm the device path (such as /dev/sdb ), otherwise it is easy to delete data by mistake. The command format is similar:

 sudo dd if=CentOS-Stream-9-latest.iso of=/dev/sdX bs=4M status=progress

After writing, the USB drive can be used as an installation disk.

Setting up BIOS boot from USB drive

After plugging in the USB flash drive, restart the computer, press the shortcut key when the boot screen just appears to enter the startup menu (usually F12, F2, Del or Esc, depending on the brand for details).
Find the "Boot Menu" or "Startup" option and turn the USB device to first. After saving and exiting, it will automatically boot from the USB drive.
Some motherboards will automatically recognize the USB drive and pop up the startup option. Just select it directly at this time, without entering the BIOS.

Details to be noted during installation

After entering the installation interface, select "Install CentOS" first to start the installation process.
The first step of setting up language and keyboard is very simple, but there are several key points next:

• Disk partitioning : Newbie recommends to select "Auto Partitioning" or "Customization". If you are reinstalling the system, remember to check "Format" to avoid accidentally deleting data.
• Network settings : The default is DHCP. If you need a fixed IP, you can configure it during installation.
• root password and user creation : Don’t forget to set the root password. It is also recommended to create a new ordinary user for daily use.
• Software selection : Minimal is the cleanest installation and is suitable for servers; the desktop version with GUI is suitable for local developers or newbies.

When installing CentOS 8 and 9, it may also be prompted to connect to Red Hat Insights, just skip it.

Basically that's it. The whole process seems a bit too many, but in fact each step is not complicated, just pay attention to the details, especially the partition and BIOS settings.

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