shell for循环练习题-等边三角形

[root@localhost ~]# cat sanjiaoxing.sh 
#!/bin/bash
# Crushlinux
# 2017-04-10 
read -p "请输入等边三角形一条边的长度：" long
for ((a=1;a<=long;a++))
do 
	echo -n "              "
	for (( b=$long;b>a;b--)) #控制空格输出
	do 	
		echo  -n " "
	done
	for c in `seq 1 $a` #输出所在行数相同的数字个数
	do 
		echo -n "$a"
	done
	for d in `seq 2 $a`   #输出所在行数减一的数字个数
	do 
		echo -n "$a"
	done	
	echo ""  
done


[root@localhost ~]# bash sanjiaoxing.sh
请输入等边三角形一条边的长度：8
                     1
                    222
                   33333
                  4444444
                 555555555
                66666666666
               7777777777777
              888888888888888