Linux systems are everywhere today, even in companies once considered "pure Windows." If you’re a sysadmin, network administrator, or developer in a small Windows shop, you may have to jump in and fix a system problem when your site goes down. What if you have no Linux knowledge? This short guide provides tips to help you survive. Linux systems may appear in your shop as virtual machines or in the cloud, including web servers, databases, mobile device managers, version control, and monitoring systems. When one of them falters, this primer leads you through some diagnostic and recovery tasks so you can quickly get your site back up. Connect to a Linux system with OpenSSH and PuTTY secure shells List files and directories, and move around within the file system Safely inspect the file contents without changing them Narrow your search by using commands to locate specific files Use the grep command to search for error messages inside a file Determine real-time system state to find underlying problems Examine disk utilization and zero in on space-hogging files Transfer suspect files from Linux to Windows for later analysis Use commands to start, stop, restart, or even kill unresponsive services Know where to find help when troubleshooting isn’t enough