The Linux System Monitoring Tools

The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues such as:

Finding out bottlenecks.
Disk (storage) bottlenecks.
CPU and memory bottlenecks.
Network bottlenecks.

1. top  : Process activity command, provides a dynamic real-time view of a running system.

2. vmstat  : System Activity, Hardware and System Information, reports virtual memory information about processes, memory, paging, block IO, traps, and cpu activity.

3. w  : Find out who is logged on and what they are doing.

4. uptime  : Tell how long the system has been running. 

5. ps  : Displays the processes.

6. free  : Memory usage.

7. iostat  : Average CPU load, Disk activity, report CPU statistics and input/output statistics for devices, partitions and network filesystems (NFS).

8. sar  : Used to collect, report, and save system activity information. 

9. mpstat  : Displays activities for each available processor, processor 0 being the first one. 

10. pmap  : Reports memory map of a process.

11. netstat  : Displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.

12. ss    : Is used to dump socket statistics.

13. iptraf   : Real-time Network Statistics, generates various network statistics including TCP info, UDP counts, ICMP and OSPF information, Ethernet load info, node stats, IP checksum errors, and others. 

14. tcpdump  : Detailed network traffic analysis, need good understanding of TCP/IP protocol to utilize this tool.

15. strace  : Trace system calls and signalsl

16. /Proc file system  : Provides detailed information about various hardware devices and other Linux kernel information.

 cat /proc/cpuinfo
 cat /proc/meminfo
 cat /proc/zoneinfo
 cat /proc/mounts

17. Nagios  : Server and network monitoring, Nagios is a popular open source computer system and network monitoring application software. You can easily monitor all your hosts, network equipment and services.

18. Cacti  : Web-based monitoring tool, Cacti is a complete network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality. 

19. KDE System Guard  : Real-time systems reporting and graphing.

20. Gnome System Monitor : Real-time systems reporting and graphing.

The System Monitor application enables you to display basic system information and monitor system processes, usage of system resources, and file systems.

    Displays various basic information about the computer's hardware and software.
    Linux Kernel version
    GNOME version
    Hardware
    Installed memory
    Processors and speeds
    System Status
    Currently available disk space
    Processes
    Memory and swap space
    Network usage
    File Systems
    Lists all mounted filesystems along with basic information about each.

21. lsof  : list open files, network connections and much more.

22. mtr  : mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool.

23. ulimit  : User limits, limit the use of system-wide resources.

24. lsmod  : list of installed modules.

25. watch  : Automated refresh of any code every specified seconds.

26. stat  : Setails of any file or file system status.

27. getconf   : To get configuration values.

28. runlevel  : Redhat run level.

29. ldd   : Print shared library dependencies.

30. rsync  : A fast, versatile, remote (and local) file-copying tool.