18 Command Line Tools to Monitor Linux Performance

<p class="wp-caption-text">Top Command Example

For more examples of Top command read :?

2. VmStat – Virtual Memory Statistics

Linux?VmStat?command used to display statistics of?virtual memory,?kernerl threads,disks,?system processes,?I/O blocks,?interrupts,?CPU activity?and much more. By default vmstat command is not available under Linux systems you need to install a package calledsysstat?that includes a vmstat program. The common usage of command format is.

# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----

r  b   swpd   free  inact active   si   so    bi    bo   in   cs us sy id wa st

1  0      0 810420  97380  70628    0    0   115     4   89   79  1  6 90  3  0

For more Vmstat examples read :?

3. Lsof – List Open Files

Lsof?command used in many?Linux/Unix?like system that is used to display list of all the open files and the processes. The open files included are?disk files,?network sockets,pipes,?devices?and?processes. One of the main reason for using this command is when a disk cannot be unmounted and displays the error that files are being used or opened. With this commmand you can easily identify which files are in use. The most common format for this command is.

# lsof
COMMAND     PID      USER   FD      TYPE     DEVICE     SIZE       NODE NAME

init          1      root  cwd       DIR      104,2     4096          2 /

init          1      root  rtd       DIR      104,2     4096          2 /

init          1      root  txt       REG      104,2    38652   17710339 /sbin/init

init          1      root  mem       REG      104,2   129900     196453 /lib/ld-2.5.so

init          1      root  mem       REG      104,2  1693812     196454 /lib/libc-2.5.so

init          1      root  mem       REG      104,2    20668     196479 /lib/libdl-2.5.so

init          1      root  mem       REG      104,2   245376     196419 /lib/libsepol.so.1

init          1      root  mem       REG      104,2    93508     196431 /lib/libselinux.so.1

init          1      root   10u     FIFO       0,17                 953 /dev/initctl

More lsof command usage and examples :?

4. Tcpdump – Network Packet Analyzer

Tcpdump?one of the most widely used command-line?network packet analyzer?or?packets sniffer?program that is used capture or filter?TCP/IP?packets that received or transferred on a specific interface over a network. It also provides a option to save captured packages in a file for later analysis. tcpdump is almost available in all major Linux distributions.

# tcpdump -i eth0
tcpdump: verbose output suppressed,use -v or -vv for full protocol decode

listening on eth0,link-type EN10MB (Ethernet),capture size 96 bytes

22:08:59.617628 IP tecmint.com.ssh > 115.113.134.3.static-mumbai.vsnl.net.in.28472: P 2532133365:2532133481(116) ack 3561562349 win 9648

22:09:07.653466 IP tecmint.com.ssh > 115.113.134.3.static-mumbai.vsnl.net.in.28472: P 116:232(116) ack 1 win 9648

22:08:59.617916 IP 115.113.134.3.static-mumbai.vsnl.net.in.28472 > tecmint.com.ssh: . ack 116 win 64347

For more tcpdump usage read :?

5. Netstat – Network Statistics

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