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