Shell脚本———比较整数大小经典案例
方法1：传参#!/bin/bash
##############################################################
# File Name: compare1.sh
# Version: V7.4
# Author: feng yu
# Organization: http://blog.51cto.com/13520761
# Created Time : 2018-03-26 17:22:20
# Description:
##############################################################
[ $# -ne 2 ] && echo "请输入2个参数" && exit 2 ---参数个数不等于2时，提示请输入2个参数，并退出
expr $1 + 1 &>/dev/null
[ $? -eq 2 ] && echo "请输入整数" && exit 2 ---判断第一个参数是否为整数，不是整数，提示请输入整数，并退出
expr $2 + 1 &>/dev/null
[ $? -eq 2 ] && echo "请输入整数" && exit 2 ---判断第二个参数是否为整数，不是整数，提示请输入整数，并退出
[ $1 -eq $2 ] && echo "$1 = $2"
[ $1 -lt $2 ] && echo "$1 < $2"
[ $1 -gt $2 ] && echo "$1 > $2"
方法2：传参（if表达式）
#!/bin/bash
##############################################################
# File Name: compare.sh
# Version: V7.4
# Author: feng yu
# Organization: http://blog.51cto.com/13520761
# Created Time : 2018-03-26 16:20:43
# Description:
##############################################################
if ! [ $# -eq 2 ];then
echo "请输入2个参数"
exit
fi
expr $1 + 1 &>/dev/null
if [ $? -eq 2 ];then
echo "请输入整数"
exit
fi
expr $2 + 1 &>/dev/null
if [ $? -eq 2 ];then
echo "请输入整数"
exit
fi
if [ $1 -eq $2 ];then
echo "$1 = $2"
elif [ $1 -lt $2 ];then
echo "$1 < $2"
elif [ $1 -gt $2 ];then
echo "$1 > $2"
fi
方法3：read读入
#!/bin/bash
##############################################################
# File Name: compare2.sh
# Version: V7.4
# Author: feng yu
# Organization: http://blog.51cto.com/13520761
# Created Time : 2018-03-26 18:20:14
# Description:
##############################################################
read -p "请输入整数：" num1
expr $num1 + 1 &> /dev/null
[ $? -eq 2 ] && echo "请输入整数" && exit 2
[ -z "$num1" ] && echo "请输入一个整数" && exit 2
read -p "请输入整数：" num2
expr $num2 + 1 &> /dev/null
[ $? -eq 2 ] && echo "请输入整数" && exit 2
[ -z "$num2" ] && echo "请输入一个整数" && exit 2
[ $num1 -eq $num2 ] && echo "$num1 = $num2"
[ $num1 -gt $num2 ] && echo "$num1 > $num2"
[ $num1 -lt $num2 ] && echo "$num1 < $num2"
方法4：read读入（if表达式）
#!/bin/bash
##############################################################
# File Name: compare2.sh
# Version: V7.4
# Author: feng yu
# Organization: http://blog.51cto.com/13520761
# Created Time : 2018-03-26 18:20:14
# Description:
##############################################################
read -p "请输入整数：" num1
expr $num1 + 1 &> /dev/null
if [ $? -eq 2 ];then
echo "请输入整数"
exit 2
fi
if [ -z "$num1" ];then
echo "请输入一个整数"
exit 2
fi
read -p "请输入整数：" num2
expr $num2 + 1 &> /dev/null
if [ $? -eq 2 ];then
echo "请输入整数"
exit 2
fi
if [ -z "$num2" ];then
echo "请输入一个整数"
exit 2
fi
if [ $num1 -eq $num2 ];then
echo "$num1 = $num2"
elif [ $num1 -gt $num2 ];then
echo "$num1 > $num2"
elif [ $num1 -lt $num2 ];then
echo "$num1 < $num2"
fi
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