shell脚本，通过传入的参数来计算最大值和最小值以及平均值。

[root@localhost zuoye]# cat quansges.sh
#!/bin/bash 

 > file
[ ! $#  -ge   ] &&  echo "please input three number or more number!" && exit  || echo $* >file

for i in $*
do
  expr $i +   &> /dev/null
 [  $?  -ne    ] && echo "input is error" && exit
done

      a=`cat file |xargs -n1|sort -n|head -`
      b=`cat file |xargs -n1|sort -n|tail -`
      c=`cat file |xargs -n1|sort -n|wc -l`

     d=`cat file |xargs -n1|awk '{a+=$1}'END'{print a}'`

#[ $b -ne  ] &&
echo "max number:"$b
#[ $a -ne  ] &&

 echo "min number:"$a

echo "average is:" `awk 'BEGIN{printf "%.2f\n", '$d'/'$c'}'`

[root@localhost zuoye]# bash quansges.sh  d
input is error
[root@localhost zuoye]# bash quansges.sh d d
input is error
[root@localhost zuoye]# bash quansges.sh d d d
input is error
[root@localhost zuoye]# bash quansges.sh d
input is error
[root@localhost zuoye]# bash quansges.sh
max number:
min number:
average is: 4.50
[root@localhost zuoye]# bash quansges.sh
max number:
min number:
average is: 5.50
[root@localhost zuoye]#