#!/bin/bash

 #Program: # #History: #2018/11/10 LY first release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH

read -p "please input a number, I will count for 1+2+3+...+your_input: " nu s=0 for ( ( i=1; i<=$nu; i=i+1 ) ) do s=$ ( ($s+$i) ) done" echo "the result of '1+2+3+...+$nu' is ==> $s"  

假設執行一直出現一個錯誤是

please input a number, I will count for 1+2+3+...+your_input: 10 sh09.sh: line 11: syntax error near unexpected token `(' sh09.sh: line 11: `for ( ( i=1; i<=$nu; i=i+1 ) )'

有兩種解決方法：第一種：可以將

for ( ( i=1; i<=$nu; i=i+1 ) )  改成for (( i=1; i<=$nu; i=i+1 ))

s=$ ( ($s+$i ) ) 改成 s=$[$s+$i]

第二種 刪除括號之間的空格

for ( ( i=1; i<=$nu; i=i+1 ) )  改成for (( i=1; i<=$nu; i=i+1 ))

s=$ ( ($s+$i ) ) 改成 s=$(($s+$i))

PS：若有不合理之處，望留言