循环case语句而不退出shell脚本

我有一个简单的shell脚本来选择diff任务并执行它。 如果选择选项1,它将执行该任务并退出脚本。

但我希望脚本等待用户输入另一个任务并执行它,直到用户手动退出。

假设用户首先选择选项1并获得输出。接下来,用户希望选择选项2,并应获得输出。直到他手动退出脚本。

#!/bin/sh
echo "For Fruits [1] "
echo "For Vegetables [2] "
echo "For drinks [3] "
read output
case $output in 
1)
cat 1.txt | tr , '\n' | sort >epackP.txt 
cat 2.txt | tr " " '\n'| /usr/xpg4/bin/awk -F "T000" '{print $2}'|/usr/xpg4/bin/awk -F "+" '{print $1}'|sed '/^$/d' | sort >symmP.txt
diff -ibw 1.txt 2.txt
if [ $? -eq 0 ]; then
   echo "********** Files matched :D **********"  
else
   echo "********** Mismatch found :( **********"
 fi
;;
2)
cat 3.txt | tr , '\n' | sort >epackP.txt 
cat 4.txt | tr " " '\n'| /usr/xpg4/bin/awk -F "T00" '{print $2}'|/usr/xpg4/bin/awk -F "+" '{print $1}'|sed '/^$/d' | sort >symmP.txt
diff -ibw 3.txt 4.txt
if [ $? -eq 0 ]; then
   echo "********** Files matched :D **********"  
else
   echo "********** Mismatch found :( **********"
fi
;;
3)
diff -ibw 5.txt 6.txt 
if [ $? -eq 0 ]; then
   echo "********** Files matched :D **********"  
else
   echo "********** Mismatch found :( **********"
 fi
   ;;
*)
echo "retry"
esac