Server Monitoring

Few server monitoring commands:

Note: You may need to install some commands on server.
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top
top -u username
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mpstat
mpstat -P ALL
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sar

sar -u 2 5
Output (for each 2 seconds. 5 lines are displayed):
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Displays the top 10 CPU users on the Linux system.
ps -eo pcpu,pid,user,args | sort -k 1 -r | head -10
OR
ps -eo pcpu,pid,user,args | sort -r -k1 | less
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System's average CPU utilization since the last reboot.
iostat

three outputs every 5 seconds
iostat -xtc 5 3
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vmstat by default will display the memory usage (including swap) as shown below.
vmstat
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displays the memory map of the current bash shell. In this example, 5732 is the PID of the bash shell.
pmap 5732
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IPTraf is a IP Network Monitoring Software.
iptraf
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strace displays all system calls for the given executable. The following example shows the output of strace for the Linux ls command.
strace ls

strace -e open ls
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Lsof stands for ls open files
lsof | more

lsof -u ramesh

lsof /bin/vi
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Ntop is just like top, but for network traffic. ntop is a network traffic monitor that displays the network usage.
ntop
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w
uptime
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Use “vnstat -t” or “vnstat –top10? to display all time top 10 traffic days.
vnstat --top10

vnstat
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htop is a ncurses-based process viewer.
htop
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ss stands for socket statistics. This displays information that are similar to netstat command.
ss -l

The following displays only the established connection.
ss -o state established

The following displays socket summary statistics.
ss -s
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iftop
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Good URLs:
http://www.thegeekstuff.com/2011/12/linux-performance-monitoring-tools/
http://blog.scoutapp.com/articles/2009/07/31/understanding-load-averages
http://www.tecmint.com/command-line-tools-to-monitor-linux-performance/