Here i’am introducing the most popular, top 5 linux monitoring tools/commands. All the Linux distributions have some built in linux monitoring tools and couple more add-ons for monitoring linux resource and performance. Including network, CPU, memory, Disk I/O, etc. Unlike Windows based servers, you are administering linux servers via command line on a shell. Since monitoring is essential for all the servers, here is the top frequently used 5 linux monitoring tools/commands.
Top 5 Linux monitoring tools
#1. “Top” command
One of the basic but essential linux monitoring tools that works on all the linuc distributions like Ubuntu, CentOS, Redhat, Debian, Fedora, etc. Top command displays all the precess running on with its PID, CPU, memory, virtual memory, time, etc. Simply press “q” to quit from the top command tool.
Top Command Usage examples (available switches -U User , -p PID , -d update intervals (in seconds)
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top |
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top -p 1776 |
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top -p 1876 -d .5 |
Sample Output:
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top - 20:21:47 up 1:42, 2 users, load average: 0.11, 0.08, 0.06 Tasks: 217 total, 2 running, 215 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.0 us, 1.0 sy, 0.0 ni, 99.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 493880 total, 358744 used, 135136 free, 11140 buffers KiB Swap: 1046524 total, 0 used, 1046524 free. 230252 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 154 root 20 0 0 0 0 S 0.3 0.0 0:02.73 kworker/0:1 1984 root 20 0 23676 3016 2460 S 0.3 0.6 0:00.68 top 1 root 20 0 29164 3716 2452 S 0.0 0.8 0:02.55 init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.02 kthreadd 3 root 20 0 0 0 0 S 0.0 0.0 0:00.24 ksoftirqd/0 5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H 7 root 20 0 0 0 0 S 0.0 0.0 0:00.78 rcu_sched 8 root 20 0 0 0 0 R 0.0 0.0 0:00.25 rcuos/0 |
#2 vmstat command
vmstat command is used for displaying the information about the following resources. Process, memory, paging, CPU, disk I/O, system, Swap, etc.
Command usage:
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vmstat |
Available vmstat command switches
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-a, --active active/inactive memory -f, --forks number of forks since boot -m, --slabs slabinfo -n, --one-header do not redisplay header -s, --stats event counter statistics -d, --disk disk statistics -D, --disk-sum summarize disk statistics -p, --partition <dev> partition specific statistics -S, --unit <char> define display unit -w, --wide wide output |
Example:
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vmstat -a |
Sample Output:
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sreekanth@DigitPAGE:~$ vmstat procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 135280 11140 230252 0 0 44 27 40 103 0 0 99 0 0 |
#3. free command
Free is another simple but very usefull linux monitoring tool to monitor Memory resource usage. Free command can monitor the usage of Physical memory, virtual memory, Swap memory usage, buffer memory, cached, etc.
Command usage:
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free |
available free command switches:
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-b, --bytes show output in bytes -k, --kilo show output in kilobytes -m, --mega show output in megabytes -g, --giga show output in gigabytes --tera show output in terabytes -h, --human show human-readable output --si use powers of 1000 not 1024 -l, --lohi show detailed low and high memory statistics -o, --old use old format (without -/+buffers/cache line) -t, --total show total for RAM + swap -s N, --seconds N repeat printing every N seconds -c N, --count N repeat printing N times, then exit |
Sample output:
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sreekanth@DigitPAGE:~$ free -m total used free shared buffers cached Mem: 482 346 136 0 10 224 -/+ buffers/cache: 110 371 Swap: 1021 0 1021 |
#4 netstat command
netstat is another powerful built-in Linux monitoring tools used for getting the netword statistics. The command output displays the status of active network connections to/from the server. The output will displays the opened/ connected ports, remote/foreign ipaddres, connection state, type, etc.
command usage:
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netstat |
Sample command output:
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sreekanth@DigitPAGE:~$ netstat Active Internet connections (w/o servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 172.16.197.129:ssh 172.16.197.1:51125 ESTABLISHED udp6 0 0 localhost:51487 localhost:59966 ESTABLISHED udp6 0 0 localhost:59966 localhost:51487 ESTABLISHED Active UNIX domain sockets (w/o servers) Proto RefCnt Flags Type State I-Node Path unix 7 [ ] DGRAM 10110 /dev/log unix 2 [ ] DGRAM 20570 unix 3 [ ] STREAM CONNECTED 9879 unix 3 [ ] STREAM CONNECTED 9881 @/com/ubuntu/upstart unix 2 [ ] DGRAM 13115 unix 3 [ ] STREAM CONNECTED 12484 unix 3 [ ] STREAM CONNECTED 13333 unix 3 [ ] STREAM CONNECTED 10084 unix 3 [ ] STREAM CONNECTED 12251 /var/run/dbus/system_bus_socket |
#5 tcpdump command
tcpdump is one of the most powerful linux monitoring tools for network administration. tcpdump command will display packets i/o in a linux server. the popular command usage is monitoring the packets flow on a network interface
tcpdump command usage:
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sudo tcpdump |
Sample output:
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sreekanth@DigitPAGE:~$ sudo tcpdump -i eth0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes 20:31:41.345770 IP 172.16.197.129.ssh > 172.16.197.1.51125: Flags [P.], seq 2625823039:2625823155, ack 519009419, win 679, options [nop,nop,TS val 1614064 ecr 255900466], length 116 20:31:41.345977 IP 172.16.197.129.ssh > 172.16.197.1.51125: Flags [P.], seq 116:152, ack 1, win 679, options [nop,nop,TS val 1614064 ecr 255900466], length 36 20:31:41.346133 IP 172.16.197.1.51125 > 172.16.197.129.ssh: Flags [.], ack 116, win 8184, options [nop,nop,TS val 255900476 ecr 1614064], length 0 20:31:41.346140 IP 172.16.197.1.51125 > 172.16.197.129.ssh: Flags [.], ack 152, win 8189, options [nop,nop,TS val 255900476 ecr 1614064], length 0 20:31:41.346232 IP 172.16.197.129.ssh > 172.16.197.1.51125: Flags [P.], seq 152:268, ack 1, win 679, options [nop,nop,TS val 1614064 ecr 255900476], length 116 |
