Linux System Monitoring Tools

1.Genome System Monitor-It is a Process Viewer which is responsible for tree view process dependencies,icons for processes,hide processes that you  don't want to see,graphical time histories of CPU/memory/swap usage.

2.KDE System Guard-It is also known as KSysguard.It is a KDE task manager and performance monitor.It can monitor both local and  remote hosts.

3.Cacti-Cacti is a complete frontend to RRDTool, it stores all of the necessary information to create graphs and populate them with data in a MySQL database. The frontend is completely PHP driven.Cacti also handles the data gathering.

4.Nagios-It is an open source system monitoring,network monitoring and infrastructure monitoring software application.It alerts users when something is going wrong and also alerts when the things resolves.

5. ./proc-It displays various system hardware configuration and also displays LInux kernel information. 

6.Strace-It helps in debugging webserver and other server issues.

7.Iptraf-ncurses-based IP LAN monitor.

8.Pmap-Reports memory map of a process thereby helping to find out the causes of memory bottlenecks