条件控制语句

  1. a=20
  2. b=20
  3. if [ $a -lt $b ]
  4. then
  5.     echo "a < b"
  6. elif [ $a -gt $b ] 
  7. then
  8.     echo "a > b"
  9. else
  10.     echo "a = b"
  11. fi

for 循环

  1. # for 循环
  3. for loop in 1 3 44 55 66
  4. do
  5.     echo "the value is $loop"
  6. done
  8. # for 循环数组
  9. array=(A B C D E F 33)
  10. for i in ${array[@]}
  11. do
  12.     echo $i
  13. done
  15. for j in {1..5}
  16. do
  17.     echo $j
  18. done
  20. # for 循环数组带下标
  21. # ${!var[@] 其中 ${!}表示间接引入变量并对变量进行展开
  22. array=(1 2 3 4 5)
  23. for i in ${!array[@]}
  24. do
  25.     echo "下标是$i, 值是${array[$i]}"
  26. done

while 循环

  1. # while 循环
  2. # let 是用于计算的工具， let no++ 是自增; let no-- 是自减; let no+=20 相等于 let no=no+20
  3. int=1
  4. while(( $int<=5 ))
  5. do
  6.     echo $int
  7.     let "int++"
  8. done
  10. # 无限循环
  11. while true
  12. do
  13.     echo "无限循环"
  14. done
  16. set i=0
  17. set j=0
  18. for (( i=0; i<10; ))
  19. do
  20.     let "j+=1"
  21.     echo "----- j is $j---"
  22. done

until 循环

  1. a=0
  2. until [ ! $a -lt 10 ]
  3. do
  4.     echo $a
  5.     let "a+=1"
  6. done

case多选择语句

  1. # case ... esac 多选择语句
  2. echo "请输入你要的数字"
  3. echo "你输入的数字为："
  4. read num
  5. case $num in
  6.     1)  echo "你选择了1"
  7.     ;;
  8.     2) echo "你选择了2"
  9.     ;;
  10.     *) echo "你没有选择1或者2"
  11.     ;;
  12. esac

break

  1. # break 
  2. while true
  3. do
  4.     echo "请输入你要的数字"
  5.     echo "你输入的数字为："
  6.     read num
  7.     case $num in
  8.         1|2|3|4|5|6)  echo "你选择了$num"
  9.         ;;
  10.         *) echo "你没有选择1~6"
  11.             break
  12.         ;;
  13.     esac
  14. done

continue

  1. # continue
  2. while :
  3. do
  4.     echo -n "输入 1 到 5 之间的数字: "
  5.     read aNum
  6.     case $aNum in
  7.         1|2|3|4|5) echo "你输入的数字为 $aNum!"
  8.         ;;
  9.         *) echo "你输入的数字不是 1 到 5 之间的!"
  10.             continue
  11.             echo "游戏结束"
  12.         ;;
  13.     esac
  14. done