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LinuxShell编程从初学到精通-循环与结构化命令

news 来源：原创 2024/5/20 9:34:08

循环与结构化命令

最近正在看LinuxShell编程从初学到精通这本书，写的很详细，每一章节后面都有对应的习题，自己也亲手写了下，还有一部分没有写出来，不过正在努力。学习东西要学无止境，循序渐进，希望大家帮助优化下，或者给出更好的建议，谢谢支持！

１、使用for 循环计算１００以内所有偶数的和，然后用while循环和until循环来实现这个计算，比较哪种结构更简单；

for:

#!/bin/bash

#In addition to sum assigned value

sum=0

#Use the list for circulation calculated from 1 to 100 of all the sum of, and the value stored in sum

for i in {0..100..2}

# echo $i

let "sum+=i"

# echo $sum

done

echo "sum=$sum"

while:

#!/bin/bash

#In addition to sum assigned value

sum=0

i=0

#The use of counter control while circulation calculated from 1 to 100 of all the sum of, and the value stored in sum

while (( i <= 100 ))

let "sum+=i"

echo "sum=$sum"

let "i+=2"

echo "i=$i"

done

echo "sum=$sum"

until:

#!/bin/bash

#In addition to sum assigned value

sum=0

i=0

#The use of counter control while circulation calculated from 1 to 100 of all the sum of, and the value stored in sum

until (( i > 100 ))

let "sum+=i"

echo "sum=$sum"

let "i+=2"

echo "i=$i"

done

echo "sum=$sum"

2、使用while循环或者until循环实现从命令行诗篇字符串，直到输入的字符串为句号为止；　

while:

#!/bin/bash

#Prompt the user to enter a string

echo "Please input a string:"

read string

#The initial Chinese flag value

signal=0

while [[ "$signal" != 1 ]]

if [ "$string" != \. ]; then

echo "Not, Please try again!"

read string

else

signal=1

echo "Congratulation, you are right!"

done

until:

#!/bin/bash

#Prompt the user to enter a string

echo "Please input a string:"

read string

#The initial Chinese flag value

signal=0

until [[ "$signal" = 1 ]]

if [ "$string" != \. ]; then

echo "Not, Please try again!"

read string

else

signal=1

echo "Congratulation, you are right!"

done

3、将for_exam9.sh中输入的命令行参数改为‘１　２’，３，查看输出结果是否与原来相同；　

for_exam9.sh:

#!/bin/bash

#Prompts the user to input the number of parameters

echo "Number of arguments is $#:"

#Prompts the user to input

echo "What you input is:"

for argument

echo "$argument"

done

输出为：

[root@Shell example]# ./3.sh '1 2' 3

Number of arguments is 2:

What you input is:

1 2

4、使用for循环实现“２，４，８，１６，３２，６４”的结果显示，然后使用while和untiil实现

while:

#!/bin/bash

#On sum assignment

sum=0

#To counter I Fu in addition to value

i=1

while (( sum < 70 ))

let "sum=i*2"

let "i=sum"

if [ "$sum" -gt 64 ]

then

break

echo "$sum"

done

until:

#!/bin/bash

#On sum assignment

sum=0

#To counter I Fu in addition to value

i=1

until (( sum > 70 ))

let "sum=i*2"

let "i=sum"

if [ "$sum" -gt 64 ]

then

break

echo "$sum"

done

5、使用循环实现从１开始叠加，直到和的结果大于２０００时为止。（提示：可以通过两种方式实现，一种方式在循环条件中设置和大于２０００时结束，第二种方式使用break控制符实现）

one:

#!/bin/bash

#Environment variables

int=1

# while

while (( int <= 2000 ))

echo "$int"

let "int++"

done

two:

#!/bin/bash

#Environment variables

sum=1

signal=0

# while

while [[ "$signal" -eq 0 ]]

let "sum++"

if [ "$sum" -gt 2000 ]; then

break

echo "$sum"

done

6、找出１００以内能被３整除的数，每行显示８个数，然后换行显示；

#!/bin/bash

m=1

for (( i=1; i<100; i++ ))

let "temp1=i%3"

if [ "$temp1" -ne 0 ]

then

continue

echo -n "$i"

let "temp2=m%8"

if [ "$temp2" -eq 0 ]

then

echo " "

let "m++"

done

7、打印由如下“＊”组成的图案；

8、如果一个整数各位数字之和可以被９整除，那么　该整数就可被９整除，编写一个脚本提示用户输入一个整数，然后输出该整数，并告之该整数是否可被９整除；

#!/bin/bash

echo "Please input a number:"

read number

echo -n $number

a=$(echo $number | cut -c1 )

b=$(echo $number | cut -c2 )

c=$(echo $number | cut -c3 )

#list=$a+$b+$c

if [ -n "$a" ]; then

list=$a

if [ -n "$b" ]; then

list=`expr "$a" + "$b"`

if [ -n "$c" ]; then

list=`expr "$a" + "$b" + "$c"`

else

echo "list = ?"

echo "list=$list"

let "temp=list%9"

if [ "$temp" = 0 ]

then

echo " Can be divisible by 9."

9、编写一个脚本，该脚本提示用户输入一些整数，然后通过程序控制分别计算出这些整数中奇数之和与偶数之和，并将其输出；

(我现在做到的是只能判断奇数或偶数)

#!/bin/bash

echo "Please input some numbers:"

read num

for var in $num

echo $var

if [ `expr "$var" % 2` == 0 ]; then

echo "$var is even"

else

echo "$var is odd"

10、编写脚本提示用户输入一个正整数，程序将输出信息提示该正整数是否为质数，（提示只有2是质数，如果为奇数，且不能被任何一个小于或者等于它平方根的奇数整除，那么该奇数就是质数。）

11、一个数恰好等于它的因子之和，这样的数称为“完数”。例如，6的因子为1，2，3，而6=1+2+3，因此，6是“完数”。编写程序写出1000以内所有的完数，并按下面的格式输出其因子：

6 its factors are 1 2 3

12、编写一个脚本读入一些整数，分别输入出这些整数中的奇数的个数和偶数的个数，并输出0的个数；

13、编写一个脚本提示用户输入一个整数，程序将分别输出该整数第个位上的数字，并输出这些数字的和，例如，输出整数2345第个位上的2345；输出-3456第个位上的数字是3456；

14、使用while循环编写脚本，使其他完成下面的功能；

1）提示用户输入两个整数：firstNum和secondNum（firstNum的值一定要小于secondNum）。

2）输出所有介于firstNum和secondNum之间的奇数。

3）输出所有介于firstNum和secondNum之间的偶数之和。

#!/bin/bash
#
echo "Please input two number:(The first number is greater than the second number)"
read firstNum secondNum
nums=`echo $firstNum $secondNum | wc -w`

signal=0

if [ -n $firstNum ]; then
   echo "$firstNum"
else
   echo "Please input firstNum:"
   read firstNum
fi
if [ -n "$secondNum" ]; then
   echo "$secondNum"
else
   echo "Please input secondNum:"
   read secondNum
fi

while (( signal != 1 ))

do
    if [ "$nums" != 2 ]; then

          echo "Please input two number:"

          read firstNum secondNum

          if [ "$firstNum" -lt "$secondNum" ]; then
              echo "Please input two number:(The first number is greater than the second number"
              read firstNum secondNum
          else
              signal=1
              echo "$firstNum" is greater than "$secondNum"
          fi
    else
          signal=1
          echo "$firstNum" is greater than "$secondNum"
    fi

done