1. Write a shell script to calculate the sum of 1~100.
#! /bin/bash sum=0 for i in `seq 1 100`;do sum=$[$i+$sum] done echo $sum
2. Write a shell script, enter a number n and calculate the sum of 1~n.
Requirement: If the entered number is less than 1, re-enter until the correct number is entered.
#! /bin/bash n=0 while [$n -lt "1"];do read -p "Please input a number:"n done sum=0 for i in `seq 1 $n`;do sum=$[$i+$sum] done echo $sum
3. Write shell scripts to create users user_00, user_01...user_99 in batches.
Requirements: All users belong to the users group.
#! /bin/bash groupadd users for i in `seq -w 0 99`;do uesradd -g users user_0$i4 done
4. Write shell scripts to add users jsj01-jsj09 and jsj10-jsj99 in batches.
#! /bin/bash for((i=1;i<20;i++)); do if(i<10);then jsj="jsj0$i"; else jsj="jsj$i"; fi useradd $jsj done
5. Write a shell script, which requires the following functions: when a program is executed, the program will let the user choose boy or girl; if the user enters B or b, it will display: He is a boy; if the user enters When G or g, it will display: He is a girl;
If it is any character other than B/b/G/g, it will display: I don't know.
#! /bin/bash echo -n your choice: read choice case $choice in [g,G] echo "She is a girl." ;; [b,B] ehco "He is a boy." ;; *) echo "I don't know." ;; esac
6. Write a shell script to realize addition, subtraction, multiplication and division between two variables.
#! /bin/bash read -p "imput num1:"a read -p "input num2:"b read -p "input operator:"o case $o in +)let "res=a+b" echo $res;; -)let "res=a-b" echo $res;; /)awk'BEGIN{printf %.2f\n",'$a'/'$b'}';; *)let "res=a*b" echo $res;; esac