• Linux
• Bash
• CpuLoadAvg

Linux/Bash/CpuLoadAvg

cron job to capture load average

• script to call from cron

  • cron

    * * * * *  /home/<user>/cron-log-cpu.sh /home/<user>/cpu_usage.log
    
    }}
       * bash script cron-log-cpu.sh {{{
    #!/usr/bin/bash
    log_file="${1:-${HOME}/cpu_usage.log}"    
    
    if [[ $( awk '{ print ($1 > 2.0) }' /proc/loadavg ) -eq 1 ]];
    then 
        ( echo; date -Is; top -b -n1 -c -w | head -n 12 | grep -v "^$" ) >> ${log_file}
    else
         # Check if last update as Low loadave in last hour, should start with date
         if [[ -f ${log_file} ]] && tail -n 1 ${log_file} | grep -q "^$( date -Is | cut -c1-13)" > /dev/null; then
             :
         else
             echo
             echo "$( date -Is ) Low loadavg 1,5,15min $( cat /proc/loadavg )" >> ${log_file}
         fi  
    fi

• Log top 5 process by cpu if loadavg > 3, every minute.

  • Can remove echo after "||" to not log low load avg.

• crontab -e

  * * * * *  [[ $( echo "$(awk '{ print $1 }' /proc/loadavg) > 3" |bc ) -eq 1 ]] && ( echo; date -Is; top -b -n1 -c -w | head -n 12 ) >> ~/cpu_usage.log || echo "$( date -Is ) Low loadavg 1,5,15min $( cat /proc/loadavg )" >> ~/cpu_usage.log

• 2nd version using if else

  * * * * *  if (( $( awk '{ print ($1 > 3.0) }' /proc/loadavg ) )); then ( echo; date -Is; top -b -n1 -c -w | head -n 12 ) >> ~/cpu_usage.log; else echo "$( date -Is ) Low loadavg 1,5,15min $( cat /proc/loadavg )" >> ~/cpu_usage.log; fi

• view with

  tail -f ~/cpu_usage.log