System Monitoring Commands Tutorial
1. Introduction
System monitoring is a crucial aspect of managing a Linux-based system. It involves keeping track of various system metrics such as CPU usage, memory usage, disk I/O, and network activity. This tutorial covers some of the fundamental commands used to monitor system performance in Linux.
2. The top Command
The top command provides a dynamic, real-time view of the system's performance. It displays a list of processes running on the system along with CPU and memory usage statistics.
Example usage:
top - 15:32:12 up 10 days, 3:45, 1 user, load average: 0.58, 0.72, 0.75
Tasks: 187 total, 1 running, 186 sleeping, 0 stopped, 0 zombie
%Cpu(s): 2.0 us, 1.0 sy, 0.0 ni, 96.0 id, 0.0 wa, 0.0 hi, 1.0 si, 0.0 st
KiB Mem : 16340036 total, 819292 free, 11548440 used, 3970304 buff/cache
KiB Swap: 2097148 total, 2097148 free, 0 used. 3580120 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
123 root 20 0 162156 2048 1584 S 0.7 0.0 0:00.08 top
456 user 20 0 123456 56789 2345 S 0.3 0.3 0:05.42 some_process
3. The htop Command
The htop command is an interactive process viewer for Unix systems. It is similar to top but provides a more user-friendly and colorful interface.
Example usage:
Note: Install htop using sudo apt-get install htop if it's not already installed.
4. The vmstat Command
The vmstat (Virtual Memory Statistics) command reports information about processes, memory, paging, block IO, traps, and CPU activity.
Example usage:
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
1 0 0 819292 3970304 11548440 0 0 0 1 11 13 2 1 96 0 0
0 0 0 819292 3970304 11548440 0 0 0 1 11 13 2 0 97 0 0
5. The iostat Command
The iostat command is used for monitoring system input/output device loading by observing the time the devices are active relative to their average transfer rates.
Example usage:
Linux 4.15.0-20-generic (hostname) 09/17/2023 _x86_64_ (4 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
2.00 0.00 1.00 0.00 0.00 97.00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sda 0.50 1.00 2.00 1000 2000
6. The netstat Command
The netstat command displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.
Example usage:
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
udp 0 0 0.0.0.0:68 0.0.0.0:*
udp 0 0 127.0.0.1:631 0.0.0.0:*
7. The sar Command
The sar command collects, reports, and saves system activity information. It can be used to report on various system loads and performance metrics.
Example usage:
Linux 4.15.0-20-generic (hostname) 09/17/2023 _x86_64_ (4 CPU)
12:00:01 AM CPU %user %nice %system %iowait %steal %idle
12:00:06 AM all 2.00 0.00 1.00 0.00 0.00 97.00
12:00:11 AM all 2.00 0.00 1.00 0.00 0.00 97.00
12:00:16 AM all 2.00 0.00 1.00 0.00 0.00 97.00
Average: all 2.00 0.00 1.00 0.00 0.00 97.00
8. Conclusion
This tutorial covered several basic yet powerful commands for monitoring system performance in a Linux environment. By using these commands, system administrators can effectively monitor and troubleshoot system performance issues. Always refer to the man pages (e.g., man top, man iostat) for more detailed information and additional options.