循環與結構化命令
最近正在看LinuxShell編程從初學到精通這本書，寫的很詳細，每一章節後面都有對應的習題，自己也親手寫了下，還有一部分沒有寫出來，不過正在努力。學習東西要學無止境，循序漸進，希望大家幫助優化下，或者給出更好的建議，謝謝支持！
１、使用for 循環計算１００以內所有偶數的和，然後用while循環和until循環來實現這個計算，比較哪種結構更簡單；
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}
do
# 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 ))
do
let "sum+=i"
echo "sum=$sum"
let "i+=2"
echo "i=$i"
done
echo "sum=$sum"
until:
#!/bin/bash
#
#In addition to sum assigned value
sum=0
i=0
#The use of counter control while circulation calculated from 1 to 100 of all the sum of, and the value stored in sum
until (( i > 100 ))
do
let "sum+=i"
echo "sum=$sum"
let "i+=2"
echo "i=$i"
done
echo "sum=$sum"