Disable/Enable AP cores of cpu (Linux)

disable_enable_ap_cores.sh

#!/bin/bash

regexp='[0-9]*'

# Disable all APs
for i in /sys/devices/system/cpu/cpu*
do
   cpu=${i##*/}
   cpu_num="${cpu#cpu}"
   if expr match "$cpu_num" "\($regexp\)" > /dev/null
   then
       if [ $cpu_num -eq 0 ]
       then
           continue
       fi
     
       echo 0 > $i/online && echo $i disabled
   fi
done

cat /sys/devices/system/cpu/online
cat /sys/devices/system/cpu/offline

# Reenable all APs
for i in /sys/devices/system/cpu/cpu*
do
   cpu=${i##*/}
   cpu_num="${cpu#cpu}"
   if expr match "$cpu_num" "\($regexp\)" > /dev/null
   then
       if [ $cpu_num -eq 0 ]
       then
           continue
       fi
     
       echo 1 > $i/online && echo $i enabled
   fi
done

cat /sys/devices/system/cpu/online
cat /sys/devices/system/cpu/offline