shell判断参数是否是数字

#!/bin/bash 
   
## 方法1,有点问题
#if [[ "$1" =~ "^[[:digit:]]*$" ]];then
#if [[ "$1" =~ "^[0-9]+$" ]];then
#    echo "$1 is number."
#else
#    echo 'no.'
#fi
   
## 方法2, 可以，不过不是bash实现的，是使用了grep的正则
#if grep '^[[:digit:]]*$' <<< "$1";then
#    echo "$1 is number."
#else
#    echo 'no.'
#fi
   
## 方法3
#if [ "$1" -gt 0 ] 2>/dev/null ;then
#    echo "$1 is number."
#else
#    echo 'no.'
#fi
   
## 方法4,case
#case "$1" in
#    [1-9][0-9]*) 
#        echo "$1 is number."
#        ;;
#    *)  
#        ;;
#esac
   
## 方法5,awk
#echo $1| awk '{print($0~/^[-]?([0-9])+[.]?([0-9])+$/)?"number":"string"}'
   
## 方法5,awk
#if [ -n "$(echo $1| sed -n "/^[0-9]\+$/p")" ];then
#    echo "$1 is number."
#else
#    echo 'no.'
#fi
   
 ## 方法6,expr
expr $1 "+" 10 &> /dev/null
if [ $? -eq 0 ];then
    echo "$1 is number"
else
    echo "$1 not number"
fi