Server resource utilization monitoring

Pretty much every Linux distribution has tools to help sys admins monitor the utilization of common server resources such as CPU, memory and storage. For advanced monitoring and reporting we may need to install 3rd-party tools (e.g. Nagios or FAN) but sometimes we just want a simple way to get warnings when critical server resources may be close to overload.

Here is a set of simple shell scripts (tested in RHEL and CentOS) you can use to monitor CPU, memory and storage space. If utilization goes over a threshold these scripts will send you an email warning hopefully soon enough so that you can fix it before a system crash. Assuming you have access to basic commands like vmstat, df, mail and crontab these scripts can be setup even if you do not have root access to the server.