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Command Sys Admin Linux


Table of Conten^
Table of ContenE1
#1: top – Process Activity CommanS2
Commonly Used Hot KeyM2
#2: vmstat – System Activity, Hardware and System InformatioD3
Display Memory Utilization SlabinfA3
Get Information About Active / Inactive Memory PageM3
#3: w – Find Out Who Is Logged on And What They Are Doin33
3 4 #4: uptime – Tell How Long The System Has Been Runnin3 #5: ps – Displays The ProcesseM Show Long Format OutpuE To See Threads ( LWP and NLWP= To See Threads After ProcesseM Print All Process On The ServeK Print A Process Tre? 4 4 4 4 5

Print Security InformatioD 5

See Every Process Running As User Vive@ 5

Set Output In a User-Defined FormaE 5

Display Only The Process IDs of LighttpS 5

Display The Name of PID 55977 5

Find Out The Top 10 Memory Consuming ProcesM 5

Find Out top 10 CPU Consuming ProcesM 5

#6: free – Memory Usag? 5

#7: iostat – Average CPU Load, Disk ActivitQ 6

#8: sar – Collect and Report System ActivitQ 6 #9: mpstat – Multiprocessor Usag? 6

#10: pmap – Process Memory Usage 7

#11 and #12: netstat and ss – Network StatisticM 7 #13: iptraf – Real-time Network StatisticM 8

#14: tcpdump – Detailed Network Traffic AnalysiM 9

#15: strace – System Calls 9

#16: /Proc file system – Various Kernel StatisticM 9

17#: Nagios – Server And Network Monitorin3 10

18#: Cacti – Web-based Monitoring Too> 10

#19: KDE System Guard – Real-time Systems Reporting and Graphin3 1: #20: Gnome System Monitor – Real-time Systems Reporting and Graphin3 Bonus: Additional ToolM 11 11

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Home > CentO)

20 Linux System Monitoring Tools Every SysAdmin Should Knor

Posted by Vivek Gite <vivek@nixcraft.com> [271 CommentsC

Need to monitor Linux server performance? Try these built-in command and a few add-oD tools. Most Linux distributions are equipped with tons of monitoring. These tools provid? metrics which can be used to get information about system activities. You can use thes? tools to find the possible causes of a performance problem. The commands discusseS below are some of the most basic commands when it comes to system analysis anS debugging server issues such asG

1.@ Finding out bottlenecksD

2.@ Disk (storage) bottlenecksD

3.@ CPU and memory bottlenecksD

4.@ Network bottlenecksD

#1: top – Process Activity Commano

The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, iE displays the most CPU-intensive tasks running on the server and updates the list every five secondsD

[2C

Fig.01: Linux top commanS

Commonly Used Hot Keyg

The top command provides several useful hot keysG

Ho^

UsagX

Kef

E Displays summary information off and onD

R Displays memory information off and onD

Sorts the display by top consumers of various system resources. Useful for quick identification of performanceI

N hungry tasks on a systemD

B Enters an interactive configuration screen for top. Helpful for setting up top for a specific taskD A Enables you to interactively select the ordering within topD K Issues renice commandD @ Issues kill commandD / Turn on or off color/monA

=> Related: How do I Find Out Linux CPU Utilization? [3C

#2: vmstat – System Activity, Hardware and System Informatio]

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

# vmstat 3

Sample Outputs:

procs ———–memory———- —swap– —–io—- –system– —–cpu—–I r b swpd free buff cache si so bi bo in cs us sy id wa sE 0 0 0 2540988 522188 5130400 0 0 2 32 4 2 4 1 96 0 : 1 0 0 2540988 522188 5130400 0 0 0 720 1199 665 1 0 99 0 : 0 0 0 2540956 522188 5130400 0 0 0 0 1151 1569 4 1 95 0 : 0 0 0 2540956 522188 5130500 0 0 0 6 1117 439 1 0 99 0 : 0 0 0 2540940 522188 5130512 0 0 0 536 1189 932 1 0 98 0 : 0 0 0 2538444 522188 5130588 0 0 0 0 1187 1417 4 1 96 0 : 0 0 0 2490060 522188 5130640 0 0 0 18 1253 1123 5 1 94 0 :

Display Memory Utilization Slabinfo

# vmstat -m

Get Information About Active / Inactive Memory Pageg

# vmstat -a

=> Related: How do I find out Linux Resource utilization to detect system bottlenecks? [4C]

#3: w – Find Out Who Is Logged on And What They Are Doink

w command displays information about the users currently on the machine, and their processesD

# w username # w vive@

Sample OutputsG

17:58:47 up 5 days, 20:28, 2 users, load average: 0.36, 0.26, 0.24 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHA; root pts/0 10.1.3.145 14:55 5.00s 0.04s 0.02s vim /etc/resolv.conB root pts/1 10.1.3.145 17:43 0.00s 0.03s 0.00s +

#4: uptime – Tell How Long The System Has Been Runnink

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, anS 15 minutesD

# uptime

OutputG

18:02:41 up 41 days, 23:42, 1 user, load average: 0.00, 0.00, 0.0:

1 can be considered as optimal load value. The load can change from system to system. For a single CPU system 1 – 3 and SMP systems 6-10 load value might be acceptableD

#5: ps – Displays The Processeg

ps command will report a snapshot of the current processes. To select all processes use the -A or -e optionG

# ps -N

Sample OutputsG

PID TTY TIME CM 1 ? 00:00:02 iniE 2 ? 00:00:02 migration/: 3 ? 00:00:01 ksoftirqd/: 4 ? 00:00:00 watchdog/: 5 ? 00:00:00 migration/1 6 ? 00:00:15 ksoftirqd/1 …D ….D 4881 ? 00:53:28 jav< 4885 tty1 00:00:00 mingettQ 4886 tty2 00:00:00 mingettQ 4887 tty3 00:00:00 mingettQ 4888 tty4 00:00:00 mingettQ 4891 tty5 00:00:00 mingettQ 4892 tty6 00:00:00 mingettQ 4893 ttyS1 00:00:00 agettQ 12853 ? 00:00:00 cifsoplockS 12854 ? 00:00:00 cifsdnotifyS 14231 ? 00:10:34 lighttpS 14232 ? 00:00:00 php-cgO 54981 pts/0 00:00:00 viR 55465 ? 00:00:00 php-cgO 55546 ? 00:00:00 bind9-snmp-staE 55704 pts/1 00:00:00 pM

ps is just like top but provides more informationD

Show Long Format Output

# ps -A

To turn on extra full mode (it will show command line arguments passed to process)G

# ps -AIF

To See Threads ( LWP and NLWP}

# ps -AIFH

To See Threads After Processeg

# ps -AILM

Print All Process On The Server

# ps ax

# ps axu

Print A Process TreX

# ps -ejH

# ps axjf

# pstree

Print Security Information

# ps -eo euser,ruser,suser,fuser,f,comm,label

# ps axZ

# ps -eM

See Every Process Running As User Vivek

# ps -U vivek -u vivek u

Set Output In a User-Defined Format

# ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comR # ps axo stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comR # ps -eopid,tt,user,fname,tmout,f,wchaD

Display Only The Process IDs of Lighttpd

# ps -C lighttpd -o pid=

OR

# pgrep lighttpd

OR

# pgrep -u vivek php-cgi

Display The Name of PID 55977

# ps -p 55977 -o comm=

Find Out The Top 10 Memory Consuming Process

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

Find Out top 10 CPU Consuming Procesg

# ps -auxf | sort -nr -k 3 | head -10

#6: free – Memory Usage

The command free displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernelD

# free

Sample Output:

total used free shared buffers cacheS Mem: 12302896 9739664 2563232 0 523124 515474: -/+ buffers/cache: 4061800 8241096

Swap: 1052248 0 1052248

=> Related: :

1.@ Linux Find Out Virtual Memory PAGESIZE [5C

2.@ Linux Limit CPU Usage Per Process [6C

3.@ How much RAM does my Ubuntu / Fedora Linux desktop PC have? [7C

#7: iostat – Average CPU Load, Disk Activitf

The command iostat report Central Processing Unit (CPU) statistics and input/output statistics for devices, partitionM and network filesystems (NFS)D

# iostaE

Sample OutputsG

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009 avg-cpu: %user %nice %system %iowait %steal %idle 3.50 0.09 0.51 0.03 0.00 95.86 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtD sda 22.04 31.88 512.03 16193351 260102868 sda1 0.00 0.00 0.00 2166 18: sda2 22.04 31.87 512.03 16189010 260102688 sda3 0.00 0.00 0.00 1615 :

=> Related: : Linux Track NFS Directory / Disk I/O Stats [8C

#8: sar – Collect and Report System Activitf

The sar command is used to collect, report, and save system activity information. To see network counter, enterG

# sar -n DEV | more

To display the network counters from the 24thG

# sar -n DEV -f /var/log/sa/sa24 | more

You can also display real time usage using sarG

# sar 4 5

Sample OutputsG

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009 06:45:12 PM CPU %user %nice %system %iowait %steal %idle 06:45:16 PM all 2.00 0.00 0.22 0.00 0.00 97.78 06:45:20 PM all 2.07 0.00 0.38 0.03 0.00 97.52 06:45:24 PM all 0.94 0.00 0.28 0.00 0.00 98.78 06:45:28 PM all 1.56 0.00 0.22 0.00 0.00 98.22 06:45:32 PM all 3.53 0.00 0.25 0.03 0.00 96.19 Average: all 2.02 0.00 0.27 0.01 0.00 97.7:

=> Related: : How to collect Linux system utilization data into a file [9C

#9: mpstat – Multiprocessor Usage

The mpstat command displays activities for each available processor, processor 0 being the first one. mpstat -P ALL tA display average CPU utilization per processorG

# mpstat -P AL8

Sample OutputG

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009 06:48:11 PM CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/M 06:48:11 PM all 3.50 0.09 0.34 0.03 0.01 0.17 0.00 95.86 1218.04 06:48:11 PM 0 3.44 0.08 0.31 0.02 0.00 0.12 0.00 96.04 1000.31 06:48:11 PM 1 3.10 0.08 0.32 0.09 0.02 0.11 0.00 96.28 34.93 06:48:11 PM 2 4.16 0.11 0.36 0.02 0.00 0.11 0.00 95.25 0.0: 06:48:11 PM 3 3.77 0.11 0.38 0.03 0.01 0.24 0.00 95.46 44.8: 06:48:11 PM 4 2.96 0.07 0.29 0.04 0.02 0.10 0.00 96.52 25.91 06:48:11 PM 5 3.26 0.08 0.28 0.03 0.01 0.10 0.00 96.23 14.98 06:48:11 PM 6 4.00 0.10 0.34 0.01 0.00 0.13 0.00 95.42 3.75 06:48:11 PM 7 3.30 0.11 0.39 0.03 0.01 0.46 0.00 95.69 76.89

=> Related: : Linux display each multiple SMP CPU processors utilization individually [10]D

#10: pmap – Process Memory UsagX

The command pmap report memory map of a process. Use this command to find out causes of memory bottlenecksD

# pmap -d PI

To display process memory information for pid # 47394, enterG

# pmap -d 47394

Sample OutputsG

47394: /usr/bin/php-cgO Address Kbytes Mode Offset Device Mappin3 0000000000400000 2584 r-x– 0000000000000000 008:00002 php-cgO 0000000000886000 140 rw— 0000000000286000 008:00002 php-cgO 00000000008a9000 52 rw— 00000000008a9000 000:00000 [ anon C 0000000000aa8000 76 rw— 00000000002a8000 008:00002 php-cgO 000000000f678000 1980 rw— 000000000f678000 000:00000 [ anon C 000000314a600000 112 r-x– 0000000000000000 008:00002 ld-2.5.sA 000000314a81b000 4 r—- 000000000001b000 008:00002 ld-2.5.sA 000000314a81c000 4 rw— 000000000001c000 008:00002 ld-2.5.sA 000000314aa00000 1328 r-x– 0000000000000000 008:00002 libc-2.5.sA 000000314ab4c000 2048 —– 000000000014c000 008:00002 libc-2.5.sA ….D …..D .D 00002af8d48fd000 4 rw— 0000000000006000 008:00002 xsl.sA 00002af8d490c000 40 r-x– 0000000000000000 008:00002 libnss_files-2.5.sA 00002af8d4916000 2044 —– 000000000000a000 008:00002 libnss_files-2.5.sA 00002af8d4b15000 4 r—- 0000000000009000 008:00002 libnss_files-2.5.sA 00002af8d4b16000 4 rw— 000000000000a000 008:00002 libnss_files-2.5.sA 00002af8d4b17000 768000 rw-s- 0000000000000000 000:00009 zero (deleted= 00007fffc95fe000 84 rw— 00007ffffffea000 000:00000 [ stack C ffffffffff600000 8192 —– 0000000000000000 000:00000 [ anon C mapped: 933712K writeable/private: 4304K shared: 768000(

The last line is very importantG

mapped: 933712K total amount of memory mapped to fileM

writeable/private: 4304K the amount of private address space

shared: 768000K the amount of address space this process is sharing with otherM

=> Related: : Linux find the memory used by a program / process using pmap command [11C

#11 and #12: netstat and ss – Network Statisticg

The command netstat displays network connections, routing tables, interface statistics, masquerade connections, anS multicast memberships. ss command is used to dump socket statistics. It allows showing information similar to netstatD See the following resources about ss and netstat commandsG

ss: Display Linux TCP / UDP Network and Socket Information [12C

Get Detailed Information About Particular IP address Connections Using netstat Command [13C

#13: iptraf – Real-time Network Statisticg

The iptraf command is interactive colorful IP LAN monitor. It is an ncurses-based IP LAN monitor that generates variouM network statistics including TCP info, UDP counts, ICMP and OSPF information, Ethernet load info, node stats, IJ checksum errors, and others. It can provide the following info in easy to read formatG

Network traffic statistics by TCP connectioD

IP traffic statistics by network interface

Network traffic statistics by protoco>

Network traffic statistics by TCP/UDP port and by packet size

Network traffic statistics by Layer2 addresM

[14C Fig.02: General interface statistics: IP traffic statistics by network interface

[15C

Fig.03 Network traffic statistics by TCP connectioD

#14: tcpdump – Detailed Network Traffic Analysig

The tcpdump is simple command that dump traffic on a network. However, you need good understanding of TCP/IJ protocol to utilize this tool. For.e.g to display traffic info about DNS, enterG

# tcpdump -i eth1 ‘udp port 53T

To display all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain data, not, for example, SY< and FIN packets and ACK-only packets, enterG

# tcpdump ‘tcp port 80 and (((ip[2:2] – ((ip[0]&0xf)<<2)) – ((tcp[12]&0xf0)>>2)) != 0)T

To display all FTP session to 202.54.1.5, enterG # tcpdump -i eth1 ‘dst 202.54.1.5 and (port 21 or 20T

To display all HTTP session to 192.168.1.5G # tcpdump -ni eth0 ‘dst 192.168.1.5 and tcp and port httpT

Use wireshark to view detailed [16] information about files, enterG # tcpdump -n -i eth1 -s 0 -w output.txt src or dst port 8:

#15: strace – System Callg

Trace system calls and signals. This is useful for debugging webserver and other server problems. See how to use tA trace the process and [17] see What it is doingD

#16: /Proc file system – Various Kernel Statisticg

/proc file system provides detailed information about various hardware devices and other Linux kernel information. See Linux kernel /proc [18] documentations for further details. Common /proc examplesG

# cat /proc/cpuinfA

@ # cat /proc/meminfA # cat /proc/zoneinfA # cat /proc/mountM

17#: Nagios – Server And Network Monitorink

Nagios [19] is a popular open source computer system and network monitoring application software. You can easilQ

monitor all your hosts, network equipment and services. It can send alert when things go wrong and again when theQ get better. FAN is [20] “Fully Automated Nagios”. FAN goals are to provide a Nagios installation including most toolM provided by the Nagios Community. FAN provides a CDRom image in the standard ISO format, making it easy tA easilly install a Nagios server. Added to this, a wide bunch of tools are including to the distribution, in order to improve the user experience around NagiosD

18#: Cacti – Web-based Monitoring TooW

Cacti is a complete network graphing solution designed to harness the power of RRDTool’s data storage and graphin3 functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and useK management features out of the box. All of this is wrapped in an intuitive, easy to use interface that makes sense foK LAN-sized installations up to complex networks with hundreds of devices. It can provide data about network, CPU* memory, logged in users, Apache, DNS servers and much more. See how to install and configure Cacti networ@

graphing [21] tool under CentOS / RHELD

#19: KDE System Guard – Real-time Systems Reporting and Graphink

KSysguard is a network enabled task and system monitor application for KDE desktop. This tool can be run over ss7 session. It provides lots of features such as a client/server architecture that enables monitoring of local and remote hosts. The graphical front end uses so-called sensors to retrieve the information it displays. A sensor can return simple values or more complex information like tables. For each type of information, one or more displays are providedD Displays are organized in worksheets that can be saved and loaded independently from each other. So, KSysguard iM not only a simple task manager but also a very powerful tool to control large server farmsD

[22C Fig.05 KDE System Guard {Image credit: WikipediaY

See the KSysguard handbook [23] for detailed usageD

#20: Gnome System Monitor – Real-time Systems Reporting and Graphink

The System Monitor application enables you to display basic system information and monitor system processes, usage of system resources, and file systems. You can also use System Monitor to modify the behavior of your systemD Although not as powerful as the KDE System Guard, it provides the basic information which may be useful for ne+ usersG

Displays various basic information about the computer’s hardware and softwareD

Linux Kernel versioD

GNOME versioD

Hardware

Installed memorQ

Processors and speedM

System StatuM

Currently available disk space

ProcesseM

Memory and swap space

Network usage

File SystemM

Lists all mounted filesystems along with basic information about eachD

Fig.06 The Gnome System Monitor applicatioD

Bonus: Additional Toolg

A few more toolsG

nmap [25] – scan your server for open portsD

lsof [26] – list open files, network connections and much moreD

ntop [27] web based tool – ntop is the best tool to see network usage in a way similar to what top command doeM for processes i.e. it is network traffic monitoring software. You can see network status, protocol wise distributioD of traffic for UDP, TCP, DNS, HTTP and other protocolsD

Conky [28] – Another good monitoring tool for the X Window System. It is highly configurable and is able tA

monitor many system variables including the status of the CPU, memory, swap space, disk storage* temperatures, processes, network interfaces, battery power, system messages, e-mail inboxes etcD

GKrellM [29] – It can be used to monitor the status of CPUs, main memory, hard disks, network interfaces, loca>

and remote mailboxes, and many other thingsD

vnstat [30] – vnStat is a console-based network traffic monitor. It keeps a log of hourly, daily and monthly networ@ traffic for the selected interface(s)D

htop [31] – htop is an enhanced version of top, the interactive process viewer, which can display the list oB processes in a tree formD

mtr [32] – mtr combines the functionality of the traceroute and ping programs in a single network diagnostic toolD

Did I miss something? Please add your favorite system motoring tool in the commentsD

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URL to article: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.htmW

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[1] Image: http://www.cyberciti.biz/tips/category/linud [2] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/top-outpu^ [3] How do I Find Out Linux CPU Utilization?: http://www.cyberciti.biz/tips/how-do-i-find-out-linux-cpu-utilization.htmW [4] How do I find out Linux Resource utilization to detect system bottlenecks?: http://www.cyberciti.biz/tips/linux;

resource-utilization-to-detect-system-bottlenecks.htmW [5] Linux Find Out Virtual Memory PAGESIZE: http://www.cyberciti.biz/faq/linux-check-the-size-of-pagesizes [6] Linux Limit CPU Usage Per Process: http://www.cyberciti.biz/faq/cpu-usage-limiter-for-linuxs [7] How much RAM does my Ubuntu / Fedora Linux desktop PC have?: http://www.cyberciti.biz/tips/how-much-ram;

does-my-linux-system.htmW [8] Linux Track NFS Directory / Disk I/O Stats: http://www.cyberciti.biz/faq/howto-linux-track-nfs-client-disk-metricss [9] How to collect Linux system utilization data into a file: http://www.cyberciti.biz/tips/howto-write-system-utilization;

data-to-file.htmW

[10] Linux display each multiple SMP CPU processors utilization individually: http://www.cyberciti.biz/faq/linux-mpstat; command-report-processors-related-statisticss [11] Linux find the memory used by a program / process using pmap command: http://www.cyberciti.biz/tips/howto-find;

memory-used-by-program.htmW [12] ss: Display Linux TCP / UDP Network and Socket Information: http://www.cyberciti.biz/tips/linux-investigate; sockets-network-connections.htmW

[13] Get Detailed Information About Particular IP address Connections Using netstat CommandG

http://www.cyberciti.biz/tips/netstat-command-tutorial-examples.htmW [14] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/iptraft [15] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/iptraf_ [16] wireshark to view detailed: http://www.cyberciti.biz/faq/linux-unix-bsd-apache-tcpdump-http-packets-sniffings [17] trace the process and: http://www.cyberciti.biz/tips/linux-strace-command-examples.htmW [18] Linux kernel /proc: http://www.cyberciti.biz/files/linux-kernel/Documentation/filesystems/proc.tx^ [19] Nagios: http://www.nagios.orgs [20] FAN is: http://fannagioscd.sourceforge.net/drupals [21] to install and configure Cacti network graphing: http://www.cyberciti.biz/faq/fedora-rhel-install-cacti-monitoring-rrd;

softwares [22] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/kde-systemguard-screensho^ [23] the KSysguard handbook: http://docs.kde.org/stable/en/kdebase-workspace/ksysguard/index.htmW [24] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/gnome-system-monitoj [25] nmap: http://www.cyberciti.biz/tips/linux-scanning-network-for-open-ports.htmW [26] lsof: http://www.cyberciti.biz/tips/tag/lsof-commano [27] ntop: http://www.cyberciti.biz/faq/debian-ubuntu-install-ntop-network-traffic-monitoring-softwares [28] Conky: http://conky.sourceforge.nets [29] GKrellM: http://members.dslextreme.com/users/billw/gkrellm/gkrellm.htmW [30] vnstat: http://www.cyberciti.biz/tips/keeping-a-log-of-daily-network-traffic-for-adsl-or-dedicated-remote-linux;

box.htmW [31] htop: http://htop.sourceforge.nets [32] mtr: http://www.cyberciti.biz/tips/finding-out-a-bad-or-simply-overloaded-network-link-with-linuxunix-oses.htmW

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Table of Conten^
Table of ContenE1
#1: top – Process Activity CommanS2
Commonly Used Hot KeyM2
#2: vmstat – System Activity, Hardware and System InformatioD3
Display Memory Utilization SlabinfA3
Get Information About Active / Inactive Memory PageM3
#3: w – Find Out Who Is Logged on And What They Are Doin33
3 4 #4: uptime – Tell How Long The System Has Been Runnin3 #5: ps – Displays The ProcesseM Show Long Format OutpuE To See Threads ( LWP and NLWP= To See Threads After ProcesseM Print All Process On The ServeK Print A Process Tree 4 4 4 4 5

Print Security InformatioD 5 See Every Process Running As User Vive@ 5 Set Output In a User-Defined FormaE 5 Display Only The Process IDs of LighttpS 5

Display The Name of PID 55977 5

Find Out The Top 10 Memory Consuming ProcesM 5

Find Out top 10 CPU Consuming ProcesM 5

#6: free – Memory Usage 5

#7: iostat – Average CPU Load, Disk ActivitQ 6

#8: sar – Collect and Report System ActivitQ 6 #9: mpstat – Multiprocessor Usage 6

#10: pmap – Process Memory Usage 7

#11 and #12: netstat and ss – Network StatisticM 7 #13: iptraf – Real-time Network StatisticM 8 #14: tcpdump – Detailed Network Traffic AnalysiM 9

#15: strace – System CallM 9 #16: /Proc file system – Various Kernel StatisticM 9 17#: Nagios – Server And Network Monitorin3 1: 18#: Cacti – Web-based Monitoring Too> 1:

#19: KDE System Guard – Real-time Systems Reporting and Graphin3 1: #20: Gnome System Monitor – Real-time Systems Reporting and Graphin3 Bonus: Additional ToolM 11 11

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Home > CentO)

20 Linux System Monitoring Tools Every SysAdmin Should Knor

Posted by Vivek Gite <vivek@nixcraft.com> [271 CommentsC

Need to monitor Linux server performance? Try these built-in command and a few add-oD tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discusseS below are some of the most basic commands when it comes to system analysis anS debugging server issues such asG

1.@ Finding out bottlenecksD

2.@ Disk (storage) bottlenecksD

3.@ CPU and memory bottlenecksD

4.@ Network bottlenecksD

#1: top – Process Activity Commano

The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, iE displays the most CPU-intensive tasks running on the server and updates the list every five secondsD

[2C

Fig.01: Linux top commanS

Commonly Used Hot Keyg

The top command provides several useful hot keysG

Ho^

UsagX

Kef

E Displays summary information off and onD

R Displays memory information off and onD

Sorts the display by top consumers of various system resources. Useful for quick identification of performanceI

N hungry tasks on a systemD

B Enters an interactive configuration screen for top. Helpful for setting up top for a specific taskD A Enables you to interactively select the ordering within topD K Issues renice commandD @ Issues kill commandD / Turn on or off color/monA

=> Related: How do I Find Out Linux CPU Utilization? [3C

#2: vmstat – System Activity, Hardware and System Informatio]

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

# vmstat 3

Sample OutputsG

procs ———–memory———- —swap– —–io—- –system– —–cpu—–I r b swpd free buff cache si so bi bo in cs us sy id wa sE 0 0 0 2540988 522188 5130400 0 0 2 32 4 2 4 1 96 0 : 1 0 0 2540988 522188 5130400 0 0 0 720 1199 665 1 0 99 0 : 0 0 0 2540956 522188 5130400 0 0 0 0 1151 1569 4 1 95 0 : 0 0 0 2540956 522188 5130500 0 0 0 6 1117 439 1 0 99 0 : 0 0 0 2540940 522188 5130512 0 0 0 536 1189 932 1 0 98 0 : 0 0 0 2538444 522188 5130588 0 0 0 0 1187 1417 4 1 96 0 : 0 0 0 2490060 522188 5130640 0 0 0 18 1253 1123 5 1 94 0 :

Display Memory Utilization SlabinfZ

# vmstat -R

Get Information About Active / Inactive Memory Pageg

# vmstat -<

=> Related: How do I find out Linux Resource utilization to detect system bottlenecks? [4C

#3: w – Find Out Who Is Logged on And What They Are Doink

w command displays information about the users currently on the machine, and their processesD

# w username # w vive@

Sample OutputsG

17:58:47 up 5 days, 20:28, 2 users, load average: 0.36, 0.26, 0.24 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHA; root pts/0 10.1.3.145 14:55 5.00s 0.04s 0.02s vim /etc/resolv.conB root pts/1 10.1.3.145 17:43 0.00s 0.03s 0.00s +

#4: uptime – Tell How Long The System Has Been Runnink

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

# uptime

OutputG

18:02:41 up 41 days, 23:42, 1 user, load average: 0.00, 0.00, 0.0:

1 can be considered as optimal load value. The load can change from system to system. For a single CPU system 1 – 3 and SMP systems 6-10 load value might be acceptableD

#5: ps – Displays The Processeg

ps command will report a snapshot of the current processes. To select all processes use the -A or -e optionG

# ps -N

Sample OutputsG

PID TTY TIME CM 1 ? 00:00:02 iniE 2 ? 00:00:02 migration/: 3 ? 00:00:01 ksoftirqd/: 4 ? 00:00:00 watchdog/: 5 ? 00:00:00 migration/1 6 ? 00:00:15 ksoftirqd/1 …D ….D 4881 ? 00:53:28 jav< 4885 tty1 00:00:00 mingettQ 4886 tty2 00:00:00 mingettQ 4887 tty3 00:00:00 mingettQ 4888 tty4 00:00:00 mingettQ 4891 tty5 00:00:00 mingettQ 4892 tty6 00:00:00 mingettQ 4893 ttyS1 00:00:00 agettQ 12853 ? 00:00:00 cifsoplockS 12854 ? 00:00:00 cifsdnotifyS 14231 ? 00:10:34 lighttpS 14232 ? 00:00:00 php-cgO 54981 pts/0 00:00:00 viR 55465 ? 00:00:00 php-cgO 55546 ? 00:00:00 bind9-snmp-staE 55704 pts/1 00:00:00 pM

ps is just like top but provides more informationD

Show Long Format Outpu^

# ps -A>

To turn on extra full mode (it will show command line arguments passed to process)G

# ps -Al4

To See Threads ( LWP and NLWP}

# ps -AlF’

To See Threads After Processeg

# ps -AlLR

Print All Process On The Servej

# ps aA # ps ax1

Print A Process TreX

# ps -ej’ # ps axjB # pstree

Print Security Informatio]

# ps -eo euser,ruser,suser,fuser,f,comm,labe> # ps axN # ps -e.

See Every Process Running As User Vive

# ps -U vivek -u vivek 1

Set Output In a User-Defined Forma^

# ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comR # ps axo stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comR # ps -eopid,tt,user,fname,tmout,f,wchaD

Display Only The Process IDs of Lighttpo

# ps -C lighttpd -o pidO O: # pgrep lighttpS O: # pgrep -u vivek php-cgO

Display The Name of PID 5597

# ps -p 55977 -o commO

Find Out The Top 10 Memory Consuming Procesg

# ps -auxf | sort -nr -k 4 | head -1:

Find Out top 10 CPU Consuming Procesg

# ps -auxf | sort -nr -k 3 | head -1:

#6: free – Memory UsagX

The command free displays the total amount of free and used physical and swap memory in the system, as well as th? buffers used by the kernelD

# free

Sample OutputG

total used free shared buffers cacheS Mem: 12302896 9739664 2563232 0 523124 515474: -/+ buffers/cache: 4061800 8241096

Swap: 1052248 0 1052248

=> Related: G

1.@ Linux Find Out Virtual Memory PAGESIZE [5C 2.@ Linux Limit CPU Usage Per Process [6C 3.@ How much RAM does my Ubuntu / Fedora Linux desktop PC have? [7C

#7: iostat – Average CPU Load, Disk Activitf

The command iostat report Central Processing Unit (CPU) statistics and input/output statistics for devices, partitionM and network filesystems (NFS)D

# iostaE

Sample OutputsG

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009 avg-cpu: %user %nice %system %iowait %steal %idle 3.50 0.09 0.51 0.03 0.00 95.86 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtD sda 22.04 31.88 512.03 16193351 260102868 sda1 0.00 0.00 0.00 2166 18: sda2 22.04 31.87 512.03 16189010 260102688 sda3 0.00 0.00 0.00 1615 :

=> Related: : Linux Track NFS Directory / Disk I/O Stats [8C

#8: sar – Collect and Report System Activitf

The sar command is used to collect, report, and save system activity information. To see network counter, enterG

# sar -n DEV | more

To display the network counters from the 24thG

# sar -n DEV -f /var/log/sa/sa24 | more

You can also display real time usage using sarG

# sar 4 5

Sample OutputsG

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009 06:45:12 PM CPU %user %nice %system %iowait %steal %idle 06:45:16 PM all 2.00 0.00 0.22 0.00 0.00 97.78 06:45:20 PM all 2.07 0.00 0.38 0.03 0.00 97.52 06:45:24 PM all 0.94 0.00 0.28 0.00 0.00 98.78 06:45:28 PM all 1.56 0.00 0.22 0.00 0.00 98.22 06:45:32 PM all 3.53 0.00 0.25 0.03 0.00 96.19 Average: all 2.02 0.00 0.27 0.01 0.00 97.7:

=> Related: : How to collect Linux system utilization data into a file [9C

#9: mpstat – Multiprocessor UsagX

The mpstat command displays activities for each available processor, processor 0 being the first one. mpstat -P ALL tA display average CPU utilization per processorG

# mpstat -P AL8

Sample OutputG

Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009 06:48:11 PM CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/M 06:48:11 PM all 3.50 0.09 0.34 0.03 0.01 0.17 0.00 95.86 1218.04 06:48:11 PM 0 3.44 0.08 0.31 0.02 0.00 0.12 0.00 96.04 1000.31 06:48:11 PM 1 3.10 0.08 0.32 0.09 0.02 0.11 0.00 96.28 34.93 06:48:11 PM 2 4.16 0.11 0.36 0.02 0.00 0.11 0.00 95.25 0.0: 06:48:11 PM 3 3.77 0.11 0.38 0.03 0.01 0.24 0.00 95.46 44.8: 06:48:11 PM 4 2.96 0.07 0.29 0.04 0.02 0.10 0.00 96.52 25.91 06:48:11 PM 5 3.26 0.08 0.28 0.03 0.01 0.10 0.00 96.23 14.98 06:48:11 PM 6 4.00 0.10 0.34 0.01 0.00 0.13 0.00 95.42 3.75 06:48:11 PM 7 3.30 0.11 0.39 0.03 0.01 0.46 0.00 95.69 76.89

=> Related: : Linux display each multiple SMP CPU processors utilization individually [10]D

#10: pmap – Process Memory UsagX

The command pmap report memory map of a process. Use this command to find out causes of memory bottlenecksD

# pmap -d PI

To display process memory information for pid # 47394, enterG

# pmap -d 47394

Sample OutputsG

47394: /usr/bin/php-cgO Address Kbytes Mode Offset Device Mappin3 0000000000400000 2584 r-x– 0000000000000000 008:00002 php-cgO 0000000000886000 140 rw— 0000000000286000 008:00002 php-cgO 00000000008a9000 52 rw— 00000000008a9000 000:00000 [ anon C 0000000000aa8000 76 rw— 00000000002a8000 008:00002 php-cgO 000000000f678000 1980 rw— 000000000f678000 000:00000 [ anon C 000000314a600000 112 r-x– 0000000000000000 008:00002 ld-2.5.sA 000000314a81b000 4 r—- 000000000001b000 008:00002 ld-2.5.sA 000000314a81c000 4 rw— 000000000001c000 008:00002 ld-2.5.sA 000000314aa00000 1328 r-x– 0000000000000000 008:00002 libc-2.5.sA 000000314ab4c000 2048 —– 000000000014c000 008:00002 libc-2.5.sA ….D …..D .D 00002af8d48fd000 4 rw— 0000000000006000 008:00002 xsl.sA 00002af8d490c000 40 r-x– 0000000000000000 008:00002 libnss_files-2.5.sA 00002af8d4916000 2044 —– 000000000000a000 008:00002 libnss_files-2.5.sA 00002af8d4b15000 4 r—- 0000000000009000 008:00002 libnss_files-2.5.sA 00002af8d4b16000 4 rw— 000000000000a000 008:00002 libnss_files-2.5.sA 00002af8d4b17000 768000 rw-s- 0000000000000000 000:00009 zero (deleted= 00007fffc95fe000 84 rw— 00007ffffffea000 000:00000 [ stack C ffffffffff600000 8192 —– 0000000000000000 000:00000 [ anon C mapped: 933712K writeable/private: 4304K shared: 768000(

The last line is very importantG

mapped: 933712K total amount of memory mapped to fileM

writeable/private: 4304K the amount of private address space

shared: 768000K the amount of address space this process is sharing with otherM

=> Related: : Linux find the memory used by a program / process using pmap command [11C

#11 and #12: netstat and ss – Network Statisticg

The command netstat displays network connections, routing tables, interface statistics, masquerade connections, anS multicast memberships. ss command is used to dump socket statistics. It allows showing information similar to netstatD See the following resources about ss and netstat commandsG

ss: Display Linux TCP / UDP Network and Socket Information [12C

Get Detailed Information About Particular IP address Connections Using netstat Command [13C

#13: iptraf – Real-time Network Statisticg

The iptraf command is interactive colorful IP LAN monitor. It is an ncurses-based IP LAN monitor that generates variouM network statistics including TCP info, UDP counts, ICMP and OSPF information, Ethernet load info, node stats, IJ checksum errors, and others. It can provide the following info in easy to read formatG

Network traffic statistics by TCP connectioD

IP traffic statistics by network interface

Network traffic statistics by protoco>

Network traffic statistics by TCP/UDP port and by packet size

Network traffic statistics by Layer2 addresM

[14C Fig.02: General interface statistics: IP traffic statistics by network interface

[15C

Fig.03 Network traffic statistics by TCP connectioD

#14: tcpdump – Detailed Network Traffic Analysig

The tcpdump is simple command that dump traffic on a network. However, you need good understanding of TCP/IJ protocol to utilize this tool. For.e.g to display traffic info about DNS, enterG

# tcpdump -i eth1 ‘udp port 53T

To display all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain data, not, for example, SY< and FIN packets and ACK-only packets, enterG

# tcpdump ‘tcp port 80 and (((ip[2:2] – ((ip[0]&0xf)<<2)) – ((tcp[12]&0xf0)>>2)) != 0)T

To display all FTP session to 202.54.1.5, enterG # tcpdump -i eth1 ‘dst 202.54.1.5 and (port 21 or 20T

To display all HTTP session to 192.168.1.5G # tcpdump -ni eth0 ‘dst 192.168.1.5 and tcp and port httpT

Use wireshark to view detailed [16] information about files, enterG # tcpdump -n -i eth1 -s 0 -w output.txt src or dst port 8:

#15: strace – System Callg

Trace system calls and signals. This is useful for debugging webserver and other server problems. See how to use tA trace the process and [17] see What it is doingD

#16: /Proc file system – Various Kernel Statisticg

/proc file system provides detailed information about various hardware devices and other Linux kernel information. See Linux kernel /proc [18] documentations for further details. Common /proc examplesG

# cat /proc/cpuinfA

@ # cat /proc/meminfA # cat /proc/zoneinfA # cat /proc/mountM

17#: Nagios – Server And Network Monitorink

Nagios [19] is a popular open source computer system and network monitoring application software. You can easilQ

monitor all your hosts, network equipment and services. It can send alert when things go wrong and again when theQ get better. FAN is [20] “Fully Automated Nagios”. FAN goals are to provide a Nagios installation including most toolM provided by the Nagios Community. FAN provides a CDRom image in the standard ISO format, making it easy tA easilly install a Nagios server. Added to this, a wide bunch of tools are including to the distribution, in order to improve the user experience around NagiosD

18#: Cacti – Web-based Monitoring TooW

Cacti is a complete network graphing solution designed to harness the power of RRDTool’s data storage and graphin3 functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and useK management features out of the box. All of this is wrapped in an intuitive, easy to use interface that makes sense foK LAN-sized installations up to complex networks with hundreds of devices. It can provide data about network, CPU* memory, logged in users, Apache, DNS servers and much more. See how to install and configure Cacti networ@

graphing [21] tool under CentOS / RHELD

#19: KDE System Guard – Real-time Systems Reporting and Graphink

KSysguard is a network enabled task and system monitor application for KDE desktop. This tool can be run over ss7 session. It provides lots of features such as a client/server architecture that enables monitoring of local and remote hosts. The graphical front end uses so-called sensors to retrieve the information it displays. A sensor can return simple values or more complex information like tables. For each type of information, one or more displays are providedD Displays are organized in worksheets that can be saved and loaded independently from each other. So, KSysguard iM not only a simple task manager but also a very powerful tool to control large server farmsD

[22C Fig.05 KDE System Guard {Image credit: WikipediaY

See the KSysguard handbook [23] for detailed usageD

#20: Gnome System Monitor – Real-time Systems Reporting and Graphink

The System Monitor application enables you to display basic system information and monitor system processes, usage of system resources, and file systems. You can also use System Monitor to modify the behavior of your systemD Although not as powerful as the KDE System Guard, it provides the basic information which may be useful for ne+ usersG

Displays various basic information about the computer’s hardware and softwareD

Linux Kernel versioD

GNOME versioD

Hardware

Installed memorQ

Processors and speedM

System StatuM

Currently available disk space

ProcesseM

Memory and swap space

Network usage

File SystemM

Lists all mounted filesystems along with basic information about eachD

Fig.06 The Gnome System Monitor applicatioD

Bonus: Additional Toolg

A few more toolsG

nmap [25] – scan your server for open portsD

lsof [26] – list open files, network connections and much moreD

ntop [27] web based tool – ntop is the best tool to see network usage in a way similar to what top command doeM for processes i.e. it is network traffic monitoring software. You can see network status, protocol wise distributioD of traffic for UDP, TCP, DNS, HTTP and other protocolsD

Conky [28] – Another good monitoring tool for the X Window System. It is highly configurable and is able tA

monitor many system variables including the status of the CPU, memory, swap space, disk storage* temperatures, processes, network interfaces, battery power, system messages, e-mail inboxes etcD

GKrellM [29] – It can be used to monitor the status of CPUs, main memory, hard disks, network interfaces, loca>

and remote mailboxes, and many other thingsD

vnstat [30] – vnStat is a console-based network traffic monitor. It keeps a log of hourly, daily and monthly networ@ traffic for the selected interface(s)D

htop [31] – htop is an enhanced version of top, the interactive process viewer, which can display the list oB processes in a tree formD

mtr [32] – mtr combines the functionality of the traceroute and ping programs in a single network diagnostic toolD

Did I miss something? Please add your favorite system motoring tool in the commentsD

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URL to article: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.htmW

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[1] Image: http://www.cyberciti.biz/tips/category/linud [2] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/top-outpu^ [3] How do I Find Out Linux CPU Utilization?: http://www.cyberciti.biz/tips/how-do-i-find-out-linux-cpu-utilization.htmW [4] How do I find out Linux Resource utilization to detect system bottlenecks?: http://www.cyberciti.biz/tips/linux;

resource-utilization-to-detect-system-bottlenecks.htmW [5] Linux Find Out Virtual Memory PAGESIZE: http://www.cyberciti.biz/faq/linux-check-the-size-of-pagesizes [6] Linux Limit CPU Usage Per Process: http://www.cyberciti.biz/faq/cpu-usage-limiter-for-linuxs [7] How much RAM does my Ubuntu / Fedora Linux desktop PC have?: http://www.cyberciti.biz/tips/how-much-ram;

does-my-linux-system.htmW [8] Linux Track NFS Directory / Disk I/O Stats: http://www.cyberciti.biz/faq/howto-linux-track-nfs-client-disk-metricss [9] How to collect Linux system utilization data into a file: http://www.cyberciti.biz/tips/howto-write-system-utilization;

data-to-file.htmW

[10] Linux display each multiple SMP CPU processors utilization individually: http://www.cyberciti.biz/faq/linux-mpstat; command-report-processors-related-statisticss [11] Linux find the memory used by a program / process using pmap command: http://www.cyberciti.biz/tips/howto-find;

memory-used-by-program.htmW [12] ss: Display Linux TCP / UDP Network and Socket Information: http://www.cyberciti.biz/tips/linux-investigate; sockets-network-connections.htmW

[13] Get Detailed Information About Particular IP address Connections Using netstat CommandG

http://www.cyberciti.biz/tips/netstat-command-tutorial-examples.htmW [14] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/iptraft [15] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/iptraf_ [16] wireshark to view detailed: http://www.cyberciti.biz/faq/linux-unix-bsd-apache-tcpdump-http-packets-sniffings [17] trace the process and: http://www.cyberciti.biz/tips/linux-strace-command-examples.htmW [18] Linux kernel /proc: http://www.cyberciti.biz/files/linux-kernel/Documentation/filesystems/proc.tx^ [19] Nagios: http://www.nagios.orgs [20] FAN is: http://fannagioscd.sourceforge.net/drupals [21] to install and configure Cacti network graphing: http://www.cyberciti.biz/faq/fedora-rhel-install-cacti-monitoring-rrd;

softwares [22] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/kde-systemguard-screensho^ [23] the KSysguard handbook: http://docs.kde.org/stable/en/kdebase-workspace/ksysguard/index.htmW [24] Image: http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html/gnome-system-monitoj [25] nmap: http://www.cyberciti.biz/tips/linux-scanning-network-for-open-ports.htmW [26] lsof: http://www.cyberciti.biz/tips/tag/lsof-commano [27] ntop: http://www.cyberciti.biz/faq/debian-ubuntu-install-ntop-network-traffic-monitoring-softwares [28] Conky: http://conky.sourceforge.nets [29] GKrellM: http://members.dslextreme.com/users/billw/gkrellm/gkrellm.htmW [30] vnstat: http://www.cyberciti.biz/tips/keeping-a-log-of-daily-network-traffic-for-adsl-or-dedicated-remote-linux;

box.htmW [31] htop: http://htop.sourceforge.nets [32] mtr: http://www.cyberciti.biz/tips/finding-out-a-bad-or-simply-overloaded-network-link-with-linuxunix-oses.htmW

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