How to check CPU, Memory And Swap utilization percentage in Linux?

There are lot of commands and options available in Linux to check memory utilization but I don’t see much information to check about memory utilization percentage.Most of the times we are checking memory utilization alone and we won’t think about how much percentage is used.

If you want to know those information then you are in the right page.

This tutorial will help you to identify the memory utilization when you are facing high memory utilization frequently in Linux server. But the same time, you won’t be getting the clear utilization if you are using free -m or free -g.

These format commands falls under Linux advanced commands. It will be very useful for Linux Experts and Middle Level Linux Users.

Method-1: How to check Memory Utilization Percentage in Linux?

We can use the following combination of commands to get the work done. In this method, we are using combination of free and awk command to get the memory utilization percentage.

If you are looking for other articles which is related to memory then navigate to the following link.

For Memory Utilization Percentage without Percent Symbol:

$ free -t | awk 'NR == 2 {print "Current Memory Utilization is : " $3/$2*100}'
or
$ free -t | awk 'FNR == 2 {print "Current Memory Utilization is : " $3/$2*100}'

Current Memory Utilization is : 20.4194

For Swap Utilization Percentage without Percent Symbol:

$ free -t | awk 'NR == 3 {print "Current Swap Utilization is : " $3/$2*100}'
or
$ free -t | awk 'FNR == 3 {print "Current Swap Utilization is : " $3/$2*100}'

Current Swap Utilization is : 0

For Memory Utilization Percentage with Percent Symbol and two decimal places:

$ free -t | awk 'NR == 2 {printf("Current Memory Utilization is : %.2f%"), $3/$2*100}'
or
$ free -t | awk 'FNR == 2 {printf("Current Memory Utilization is : %.2f%"), $3/$2*100}'

Current Memory Utilization is : 20.42%

For Swap Utilization Percentage with Percent Symbol and two decimal places:

$ free -t | awk 'NR == 3 {printf("Current Swap Utilization is : %.2f%"), $3/$2*100}'
or
$ free -t | awk 'FNR == 3 {printf("Current Swap Utilization is : %.2f%"), $3/$2*100}'

Current Swap Utilization is : 0.00%

If you are looking for other articles which is related to memory then navigate to the following link.

 

“free” command output for better clarification:

$ free
              total        used        free      shared  buff/cache   available
Mem:          15867        3730        9868        1189        2269       10640
Swap:         17454           0       17454
Total:        33322        3730       27322

Details are follow:

  • free: free is a standard command to check memory utilization in Linux.
  • awk: awk is a powerful command which is specialized for textual data manipulation.
  • FNR == 2: It gives the total number of records for each input file. Basically it’s used to select the given line (Here, it chooses the line number 2).
  • NR == 2: It gives the total number of records processed. Basically it’s used to filter the given line (Here, it chooses the line number 2)..
  • $3/$2*100: It divides column 2 with column 3 and it multiply the results with 100.
  • printf: It used to format and print data.
  • %.2f%: By default it prints floating point numbers with 6 decimal places. Use the following format to limit  decimal places.

Method-2: How to check Memory Utilization Percentage in Linux?

We can use the following combination of commands to get this done. In this method, we are using combination of free, grep and awk command to get the memory utilization percentage.

For Memory Utilization Percentage without Percent Symbol:

$ free -t | grep Mem | awk '{print "Current Memory Utilization is : " $3/$2*100}'
Current Memory Utilization is : 20.4228

For Swap Utilization Percentage without Percent Symbol:

$ free -t | grep Swap | awk '{print "Current Swap Utilization is : " $3/$2*100}'
Current Swap Utilization is : 0

For Memory Utilization Percentage with Percent Symbol and two decimal places:

$ free -t | grep Mem | awk '{printf("Current Memory Utilization is : %.2f%"), $3/$2*100}'
Current Memory Utilization is : 20.43%

For Swap Utilization Percentage with Percent Symbol and two decimal places:

$ free -t | grep Swap | awk '{printf("Current Swap Utilization is : %.2f%"), $3/$2*100}'
Current Swap Utilization is : 0.00%

Method-1: How to check CPU utilization percentage in Linux?

We can use the following combination of commands to get this done. In this method, we are using combination of top, print and awk command to get the CPU utilization percentage.

If you are looking for other articles which is related to memory then navigate to the following link.

If it shows multiple CPU in the output then you need to use the following method.

$ top -b -n1 | grep ^%Cpu
%Cpu0  :  5.3 us,  0.0 sy,  0.0 ni, 94.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :  0.0 us,  0.0 sy,  0.0 ni, 94.7 id,  0.0 wa,  0.0 hi,  5.3 si,  0.0 st
%Cpu3  :  5.3 us,  0.0 sy,  0.0 ni, 94.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu4  : 10.5 us, 15.8 sy,  0.0 ni, 73.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu5  :  0.0 us,  5.0 sy,  0.0 ni, 95.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu6  :  5.3 us,  0.0 sy,  0.0 ni, 94.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu7  :  5.3 us,  0.0 sy,  0.0 ni, 94.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st

For CPU Utilization Percentage without Percent Symbol:

$ top -b -n1 | grep ^%Cpu | awk '{cpu+=$9}END{print "Current CPU Utilization is : " 100-cpu/NR}'
Current CPU Utilization is : 21.05

For CPU Utilization Percentage with Percent Symbol and two decimal places:

$ top -b -n1 | grep ^%Cpu | awk '{cpu+=$9}END{printf("Current CPU Utilization is : %.2f%"), 100-cpu/NR}'
Current CPU Utilization is : 14.81%

Method-2: How to check CPU utilization percentage in Linux?

We can use the following combination of commands to get this done. In this method, we are using combination of top, print/printf and awk command to get the CPU utilization percentage.

If it shows all together CPU(s) in the single output then you need to use the following method.

$ top -b -n1 | grep ^%Cpu
%Cpu(s): 15.3 us,  7.2 sy,  0.8 ni, 69.0 id,  6.7 wa,  0.0 hi,  1.0 si,  0.0 st

For CPU Utilization Percentage without Percent Symbol:

$ top -b -n1 | grep ^%Cpu | awk '{print "Current CPU Utilization is : " 100-$8}' 
Current CPU Utilization is : 5.6

For CPU Utilization Percentage with Percent Symbol and two decimal places:

$ top -b -n1 | grep ^%Cpu | awk '{printf("Current CPU Utilization is : %.2f%"), 100-$8}' 
Current CPU Utilization is : 5.40%

Details are follow:

  • top: top is one of the best command to check currently running process on Linux system.
  • -b: -b option, allow the top command to switch in batch mode. It is useful when you run the top command from local system to remote system.
  • -n1: Number-of-iterations
  • ^%Cpu: Filter the lines which starts with %Cpu
  • awk: awk is a powerful command which is specialized for textual data manipulation.
  • cpu+=$9: For each line, add column 9 to a variable ‘cpu’.
  • printf: It used to format and print data.
  • %.2f%: By default it prints floating point numbers with 6 decimal places. Use the following format to limit a decimal places.
  • 100-cpu/NR: Finally print the ‘CPU Average’ by subtracting 100, divided by the number of records.

Vinoth Kumar

Vinoth Kumar has 3.5+ years of experience in Linux server administration & RHEL certified professional. He is currently working as a Senior L2 Linux Server administrator.

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