☞卸载kernel玩一玩

卸载kernel玩一玩

废话不多说，下面开始卸载内核这一惊险之旅，特别提醒在开始之前做好虚拟机的快照，也许会造成系统无法启动，也许会出现各种错误，也许会笑着删数据库跑路，也许会从入门到放弃，，请系好安全带。 

练习

冒泡排序法

#!/bin/bash
#
#Author:jasonmc
#Date:2016-08-24
#Description:buble sort.
#

NUM_FILE=./random.txt   #get number from file
#########################################################
swap_element(){
      local tmp=0
      tmp=${NUM_SEQUENCE[$1]}
      NUM_SEQUENCE[$1]=${NUM_SEQUENCE[$2]}
      NUM_SEQUENCE[$2]=$tmp
}
show_element(){
      echo "${NUM_SEQUENCE[*]},swap $swap_count times"
}
#########################################################
#
#The original bubble sort.
bubble_sort_orgi(){
      for ((i=0;i<${#NUM_SEQUENCE[*]}-1;i++))
      do
        for ((j=0;j<${#NUM_SEQUENCE[@]}-i-1;j++))
        do
          if [ ${NUM_SEQUENCE[$j]} $1 ${NUM_SEQUENCE[$[j+1]]} ]
          then
              swap_element $j $[j+1]
              let swap_count++
          fi
        done
      done
}
#Use the original bubble sort,by increase
NUM_SEQUENCE=(`cat $NUM_FILE`)
  bubble_sort_orgi -gt
  show_element
#Use the original bubble sort,by decrease
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
  bubble_sort_orgi -lt
  show_element
#
#With a flag to mark the sequence,if the sequence has been order,stop
bubble_sort_flag(){
     flag=0
     for ((i=0;i<${#NUM_SEQUENCE[@]}-1,!flag;i++))
     do
      flag=1
      for ((j=0;j<${#NUM_SEQUENCE[*]}-i-1;j++))
      do
           if [ ${NUM_SEQUENCE[$j]} $1 ${NUM_SEQUENCE[$[j+1]]} ]
           then
         swap_element $j $[j+1]
         flag=0
         let swap_count++
           fi
      done
     done
}
#bubble with flag.
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
   bubble_sort_flag -gt
   show_element
#
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
   bubble_sort_flag -lt
   show_element
#
#Record the last position of bubble sort
bubble_sort_last(){
   current=0
   last=$[${#NUM_SEQUENCE[*]}-1]
   while [ $last -gt 0 ]
   do
      for ((i=current=0;i<last;i++))
      do
     if [ ${NUM_SEQUENCE[$i]} $1 ${NUM_SEQUENCE[$[i+1]]} ]
     then
        swap_element $i $[i+1]
        current=$i
       let swap_count++
    fi
     done
     last=$current
  done
}
#
#Record last order position.
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
   bubble_sort_last -gt
   show_element
#
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
   bubble_sort_last -lt
   show_element
#
#Bidirectional bubble sort
bubble_sort_bid(){
   head=0
   tail=$[${#NUM_SEQUENCE[*]}-1]
   while [ $head -lt $tail ]
   do
      for ((i=head;i<tail;i++))
      do
     if [ ${NUM_SEQUENCE[$i]} $1 ${NUM_SEQUENCE[$[i+1]]} ]
     then
        swap_element $i $[i+1]
        index=$i
       let swap_count++
    fi
      done 
      tail=$index
      for ((i=tail;i>head;i--))
      do
     if [ ! ${NUM_SEQUENCE[$i]} $1 ${NUM_SEQUENCE[$[i-1]]} ]
     then
        swap_element $i $[i-1]
        index=$i
        let swap_count++
    fi
     done
     head=$index
  done
}
#
#increase
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
bubble_sort_bid -gt
show_element
#
#decrease
NUM_SEQUENCE=(`cat $NUM_FILE`)
swap_count=0
bubble_sort_bid -lt
show_element
#
unset i j index head tail NUM_FILE NUM_SEQUENCE swap_count last tmp flag