Capture 4 Element of /proc/stat of CPU line in sh

Question

I am unable to capture CPU[3] to IDLE variable in shell script (/bin/sh)

Code snippet as below:-

while true; do
      CPU=$(sed -n 's/^cpu\s//p' /proc/stat)
      **IDLE=$CPU[3]**                                   # Just the idle CPU time.
      for VALUE in ${CPU} ;
      do
       TOTAL=$((TOTAL+VALUE))
       printf "%s \n\n" $VALUE
       sleep 1
       printf "%s \n" $IDLE
      done
      sleep 0.1
 done

Answer 1

You can try below script for extracting specific string elements from sed command.

#!/bin/sh

CPU=$(sed -n 's/^cpu\s//p' /proc/stat) 
IDLE=$((sed -n 's/^cpu\s//p' /proc/stat)| (cut -d' ' -f5))
printf "IDLE Check %s \n" $IDLE
printf "CPU: %s \n" $CPU

But I see extracted value is increments by one , I will look into this and update in a while , Good Luck !!!

I am getting Output as below:

IDLE Check 286857 /*value is incremented by 2 , i will update in while on this */
CPU: 32898 
CPU: 6 
CPU: 8128 
CPU: 286855  /* This value is to be extracted as example */
CPU: 27052 
CPU: 0 
CPU: 462 
CPU: 0 
CPU: 0 
CPU: 0