CentOS TroubleShoot

Error: Failed to download metadata for repo ‘appstream’: Cannot prepare internal mirrorlist: No URLs in mirrorlist — Centos 8 Fix

Go to the /etc/yum.repos.d/ directory.

cd /etc/yum.repos.d/

Run the below commands to hash the mirror-list in all yum.repos.d files then replace the existed Baseurl with the vault.centos.org

sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

Then run yum update or install any package you want

yum update -y
reboot

Sending Mail error: /usr/sbin/sendmail: No such file or directory ……………… Message not sent.

sudo dnf install mailx
yum install postfix -y
service postfix start
chkconfig postfix on