#!/bin/bash
if [ ! -f ./list ];then
 echo "Please make a file named 'list' containing the info of each content in a line."
 exit 1
fi
rm -f /tmp/list
if [ $? = 1 ];then
 echo "I could not remove /tmp/list. I will abort."
 exit 1
fi
if [ -e ./randomizedlist ];then
 ls ./randomizedlist
 echo ""
 echo "There is ./randomizedlist. Can I delete it? If I can, type y."
 read a
 if [ "$a" = "y" ];then
  rm -r ./randomizedlist
  if [ $? = 1 ];then
   echo "I could not delete ./randomizedlist. I will abort."
   exit 1
  fi
 else
  echo "I cannot generate ./randomizedlist. I will abort."
  exit 1
 fi
fi
cp ./list /tmp/list
if [ $? = 1 ];then
 echo "I could not copy ./list to /tmp/list. I will abort."
 exit 1
fi
touch ./randomizedlist
i=$(wc -l ./list|cut -d " " -f 1)
echo "The number of the lines of ./list is $i." 
while [ $i -gt 0 ];do
 n=$(echo $[$RANDOM*i/32767+1])
 echo "$n th line is selected."
 sed -n -e ${n}p /tmp/list >> ./randomizedlist
 sed -i -e ${n}d /tmp/list
 i=$[$i-1]
done
rm -r /tmp/list
exit 0