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Commandline system monitoring

Introduction

Part 1 (default system tools)

ps

Print All Process On The Server

 ps aux

Print All Process On The Server (wrapping commands)

 ps auxww

Print A Process Tree

 ps -ejH
 ps axjf
 pstree

Display Only The Process IDs of apache

 pgrep apache

Find Out The Top 10 Memory Consuming Process

 ps -auxf | sort -nr -k 4 | head -10

free

 free -o

top

By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.

 top

vmstat

The command vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity

 vmstat 3

Display Memory Utilization Slabinfo

 vmstat -m

Get Information About Active / Inactive Memory Pages

 vmstat -a

uptime

The uptime command can be used to see how long the server has been running. The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.

 uptime

watch

Default it repeatedly reruns a command every 2 seconds by default. The next command shows the output of the free command updated every 2 seconds.

 watch free

To see the interrupts occurring on your system, run the command:

 watch -n.1 'cat /proc/interrupts'	

Part II (installed system tools)

dstat

 apt-get install dstat

More info

ngrep

No arguments. Shows all traffic going through the default network card.

 ngrep -qd eth1 'HTTP' tcp port 80

Be quiet, look only at tcp packets with either source or dest port 80 on interface eth1, look for anything matching 'HTTP'.

 ngrep -qd le0 port 53

Watch all tcp and udp port 53 (nameserver) traffic on interface le0. Be quiet.

 ngrep 'USER|PASS' tcp port 21

Look only at tcp packets with either source or dest port 21, look for anything resembling an FTP login.

 ngrep -wiA 2 'user|pass' tcp port 21

atop

 apt-get install atop

The program atop is an interactive monitor to view the load on a Linux system. It shows the occupation of the most critical hardware resources (from a performance point of view) on system level, i.e. cpu, memory, disk and network.

When running atop interactively (no output redirection), keys can be pressed to control the output. In general, lower case keys can be used to show other information for the active processes and upper case keys can be used to influence the sort order of the active process list.

g # Show generic output (default). m # Show memory related output. d # Show disk-related output. n # Show network related output (when kernel patch 'cnt' is installed). s # Show scheduling characteristics. v # Show various process characteristics. c # Show the command line of the process. u # Show the process activity accumulated per user. p # Show the process activity accumulated per program (i.e. process name).

Useful website: http://www.atoptool.nl for patch and more info. The man page is very useful too ;)

nethogs

Instead of breaking the traffic down per protocol or per subnet, like most tools do, it groups bandwidth by process. If there's suddenly a lot of network traffic, you can fire up NetHogs and immediately see which PID is causing this.

 apt-get install nethogs

More info: http://nethogs.sourceforge.net

iostat

 apt-get install iostat

 iostat

bmon

 apt-get install bmon

Just type bmon to see your network activity/bandwith in real time ;)

 bmon

inotify, incron and authctl

There is a separate page about Monitoring file system events with inotify, incron and authctl. Very usefull if you want to know what files are created or modified.

Stress

 apt-get install stress

 stress -c 20 -i 4 --verbose --timeout 1h

Others

I don't use the next tools, but maybe you like them.

• sar - Collect and Report System Activity
• multitail – tail multiple files in a single terminal window
• swatch – track your log files and fire off alerts
• iftop - display bandwidth usage on an interface by host

Resources

• http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html
• http://www.informit.com/articles/article.aspx?p=770644
• http://www.bebits.com/app/3270 ngrep

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