In Linux system, using the usermod command to add users to the secondary group is: 1. Execute the sudousermod-a-G group name username command to add, where -a means append to avoid overwriting the original secondary group; 2. Use groups username or grep group name /etc/group to verify whether the operation is successful; 3. Note that the modification only takes effect after the user logs in again, and the main group modification should use the -g parameter; 4. You can also manually edit the /etc/group file to add users, but be careful to avoid system abnormalities caused by format errors.

To migrate from CentOS8 to AlmaLinux or RockyLinux, follow the clear steps. First, choose AlmaLinux (suitable for long-term enterprise support) or RockyLinux (emphasizing exactly the same as RHEL) according to your needs. Secondly, prepare the system environment: update the software package, back up key data, check third-party repositories and disk space. Then, the conversion is automatically completed using the official migration script. RockyLinux needs to clone the repository and run the switch-to-rocky.sh script. AlmaLinux replaces the repository and upgrades with one click through the remote deployment script. Finally, verify system information, clean up residual packets, and update GRUB and ini if ??necessary

To correctly install the local RPM file and handle dependencies, you should first use dnf to install it directly, because it can automatically obtain the required dependencies from the configured repository; if the system does not support dnf, you can use yum's localinstall command instead; if the dependency cannot be resolved, you can manually download and install all related packages; finally, you can also forcefully ignore the dependency installation, but this method is not recommended. 1. Use sudodnfinstall./package-name.rpm to automatically resolve dependencies; 2. If there is no dnf, you can use sudoyumlocalinstall./package-name.rpm; 3. Force installation and execute sudorpm-ivh--nod

How to set a static IP address using nmcli on CentOS8 or 9? 1. First run the nmcliconnectionshow and ipa commands to view the current network interface and its configuration; 2. Use the nmcliconnectionmodify command to modify the connection configuration, specify parameters such as ipv4.methodmanual, ipv4.addresses (such as 192.168.1.100/24), ipv4.gateway (such as 192.168.1.1), and ipv4.dns (such as 8.8.8.8). 3. Run the nmcliconnectiondown and up commands to restart the connection to make the changes take effect, or

The method to prevent software package updates in Linux systems varies from distribution to distribution. It can be mainly implemented in the following ways: 1. Use sudoapt-markhold package name to lock the package version in Ubuntu/Debian, and use sudoapt-markunhold package name to restore updates; 2. When temporarily updated in CentOS/Fedora, skip specific packages through the --exclude= package name parameter, or edit /etc/yum.conf to add exclude= package name to achieve permanent exclusion; 3. Advanced users can use APT's pinning mechanism to set source priority to control the installation version; 4. Note that third-party package managers such as snap and flatpak need to be handled separately

AminimalinstallofCentOSisalightweightsetupthatincludesonlyessentialcomponents,makingitidealforserversorsystemsrequiringfullcontrol.Itcontainscoreutilitieslikebash,yum/dnf,networkingtools,andsecuritypackages,whileexcludingdesktopenvironments,webserver

The current running mode of SELinux can be viewed through the command line. Use getenforce command to directly display the current status, and the output is Enforcing, Permissive or Disabled; view the /etc/selinux/config file to know the default startup mode; temporarily change the mode can be setenforce1 (enforcing) or setenforce0 (permissive), but restore the configuration file settings after restart; in actual applications, you need to pay attention to service compatibility issues, and switch modes to troubleshoot problems if necessary.

To grant sudo permissions to Linux users, there are two main methods: one is to modify the /etc/sudoers file through visudo to add authorization rules, and the other is to add the user to the default sudo group. 1. Use the visudo command to add "usernameALL=(ALL)ALL" to grant full permissions. If you need to exempt password, add NOPASSWD option, but you should use it with caution; 2. Use the "usermod-aGsudousername" command to add the user to the sudo group. The operation is simple and safer. After the change, the user needs to log in again to take effect. After the configuration is completed, you can execute "sudols/