To upgrade the operating system and software on the server, use the following commands:

Debian

1. Update the indexes of the packages
   

   apt-get update

2. Update all installed packages
   

   apt-get upgrade

Ubuntu

1. Update the indexes of the packages
   

   sudo apt-get update

2. Update all installed packages
   

   sudo apt-get upgrade

Centos

1. Update all installed packages
   

   yum update