Shell 练习题 20180123

if [ $# != 1 ]
then
    echo "Usage: $0 number"
    exit 1
else
    for((i=1;i<=$1;i++))
    do
        for((j=$1;j>i;j--))
        do
            echo -n " "
        done
        for k in `seq 1 $i`
        do
            echo -n "* "
        done
        echo 
    done
fi

[root@localhost ~]# sh 1.sh 5
    * 
   * * 
  * * * 
 * * * * 
* * * * * 
[root@localhost ~]# sh 1.sh 6
     * 
    * * 
   * * * 
  * * * * 
 * * * * * 
* * * * * * 
[root@localhost ~]# sh 1.sh 7
      * 
     * * 
    * * * 
   * * * * 
  * * * * * 
 * * * * * * 
* * * * * * *