Inspired by this question: To calculate the total CPU usage as a percentage

I wrote the following bash script (as an answer) to calculate the CPU usage for a (configurable) period over all CPU cores on a host.

#!/bin/bash

#CORECOUNT=$(grep cpu /proc/stat | grep -v 'cpu ' | wc -l)
#echo $CORECOUNT cores not needed for calculation though

DELAY=${1:-1}

function getstat() {
    grep 'cpu ' /proc/stat | sed -e 's/  */x/g' -e 's/^cpux//'
}

function extract() {
    echo $1 | cut -d 'x' -f $2
}

function change() {
    local e=$(extract $ENDSTAT $1)
    local b=$(extract $STARTSTAT $1)
    local diff=$(( $e - $b ))
    echo $diff
}

#Record the start statistics

STARTSTAT=$(getstat)

sleep $DELAY

#Record the end statistics

ENDSTAT=$(getstat)


#http://www.mjmwired.net/kernel/Documentation/filesystems/proc.txt#1236
#echo "From $STARTSTAT"
#echo "TO   $ENDSTAT"
#     usr    nice   sys     idle       iowait irq    guest
#From 177834 168085 1276260 3584351494 144468 154895 0 0 0 0
#TO   177834 168085 1276261 3584351895 144468 154895 0 0 0 0

USR=$(change 1)
SYS=$(change 3)
IDLE=$(change 4)
IOW=$(change 5)

#echo USR $USR SYS $SYS IDLE $IDLE IOW $IOW

ACTIVE=$(( $USR + $SYS + $IOW ))
TOTAL=$(($ACTIVE + $IDLE))
PCT=$(( $ACTIVE * 100 / $TOTAL ))

echo "BUSY $ACTIVE TOTAL $TOTAL $PCT %"

The key features I wanted to ensure are just a single read of the stat file at the beginning, and another single read at the end.

There is some debate about what constitutes 'active' time (Is IOWait busy, or idle time?) If you have insights on that, I would appreciate that too.

All suggestions and criticisms welcome.

Inspired by this question: To calculate the total CPU usage as a percentage

I wrote the following bash script (as an answer) to calculate the CPU usage for a (configurable) period over all CPU cores on a host.

#!/bin/bash

#CORECOUNT=$(grep cpu /proc/stat | grep -v 'cpu ' | wc -l)
#echo $CORECOUNT cores not needed for calculation though

DELAY=${1:-1}

function getstat() {
    grep 'cpu ' /proc/stat | sed -e 's/  */x/g' -e 's/^cpux//'
}

function extract() {
    echo $1 | cut -d 'x' -f $2
}

function change() {
    local e=$(extract $ENDSTAT $1)
    local b=$(extract $STARTSTAT $1)
    local diff=$(( $e - $b ))
    echo $diff
}

#Record the start statistics

STARTSTAT=$(getstat)

sleep $DELAY

#Record the end statistics

ENDSTAT=$(getstat)


#http://www.mjmwired.net/kernel/Documentation/filesystems/proc.txt#1236
#echo "From $STARTSTAT"
#echo "TO   $ENDSTAT"
#     usr    nice   sys     idle       iowait irq    guest
#From 177834 168085 1276260 3584351494 144468 154895 0 0 0 0
#TO   177834 168085 1276261 3584351895 144468 154895 0 0 0 0

USR=$(change 1)
SYS=$(change 3)
IDLE=$(change 4)
IOW=$(change 5)

#echo USR $USR SYS $SYS IDLE $IDLE IOW $IOW

ACTIVE=$(( $USR + $SYS + $IOW ))
TOTAL=$(($ACTIVE + $IDLE))
PCT=$(( $ACTIVE * 100 / $TOTAL ))

echo "BUSY $ACTIVE TOTAL $TOTAL $PCT %"

The key features I wanted to ensure are just a single read of the stat file at the beginning, and another single read at the end.

There is some debate about what constitutes 'active' time (Is IOWait busy, or idle time?) If you have insights on that, I would appreciate that too.

All suggestions and criticisms welcome.