2018-02-22 13:03:01 +00:00
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#!/bin/bash
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# by Paul Colby (http://colby.id.au), no rights reserved ;)
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# https://github.com/Leo-G/DevopsWiki/wiki/How-Linux-CPU-Usage-Time-and-Percentage-is-calculated
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PREV_TOTAL=0
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PREV_IDLE=0
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while true; do
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# Get the total CPU statistics, discarding the 'cpu ' prefix.
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CPU=(`sed -n 's/^cpu\s//p' /proc/stat`)
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IDLE=${CPU[3]} # Just the idle CPU time.
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# Calculate the total CPU time.
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TOTAL=0
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for VALUE in "${CPU[@]}"; do
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let "TOTAL=$TOTAL+$VALUE"
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done
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# Calculate the CPU usage since we last checked.
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let "DIFF_IDLE=$IDLE-$PREV_IDLE"
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let "DIFF_TOTAL=$TOTAL-$PREV_TOTAL"
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let "DIFF_USAGE=(1000*($DIFF_TOTAL-$DIFF_IDLE)/$DIFF_TOTAL+5)/10"
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echo -e "$DIFF_USAGE%\n$DIFF_USAGE%"
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# Remember the total and idle CPU times for the next check.
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PREV_TOTAL="$TOTAL"
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PREV_IDLE="$IDLE"
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# Wait before checking again.
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sleep 1
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done
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