第二周作业

一、求三个数中的最大数

#!/bin/bash

if [ $2 -ge $1 ]; then

if [ $2 -ge $3 ]; then

echo "$2 is the max number!"

else

echo "$3 is the max number!"

fi

elif [ $1 -ge $3 ]; then

echo "$1 is the max number!"

else

echo "$3 is the mx number!"

fi

二、ping B 类网和C 类网

#!/bin/bash
#
for I in {1..10}; do
for A in {1..10};do
if ping -c1 -W1 172.16.$I.$A &>/dev/dull; then
echo " 172.16.$I.$A is online~"
else
echo " 172.16.$I.$A is offline~"
fi
done
done

#!/bin/bash
for I in {1..20}; do
if ping -c1 -W1 192.168.0.$I &> /dev/null ; then
echo "192.168.0.$I is online~"
else
echo "192.168.0.$I is offline~"
fi
done

三、输入 一用户名，判断其是还口存在，若存在，判断基使用的默认shell

#!/bin/bash
echo "Input a username:"
read N

if cut -d: -f1 /etc/passwd | grep "^$N$" &> /dev/null; then
echo "the shell of $N is :`grep "^$N" /etc/passwd | cut -d: -f7`"
else
echo "$N do not exist!"
fi

四、使用while语句计算100以内偶数的和

#!/bin/bash
let SUM=0
let I=0
while [ $I -le 100 ]; do
let SUM+=$I
let I+=2
done
echo $SUM

五、监控系统登录人数 超过4个 显示提示 5秒钟检查一下 并退出脚本（exit）

#!/bin/bash
while [ true ]; do
if [ `who | wc -l` -gt 4 ]; then
echo "Wow,so many users are working on me~"
exit 0
else
echo "******so boring*******"
fi
sleep 5
done

六、写个脚本 通过查找 BOOTPROTO，判断
如果BOOTPROTO=dhcp，bootp， 则 改为 static
并
修改
IPADDR=

NETMASK= 有则修改，无则追加

#!/bin/bash
STR=cat /etc/sysconfig/network-scripts/ifcfg-eth0 | grep BOOTPROTO | cut -d"=" -f2
if [ $STR == "dhcp" ]; then
sed 's/^BOOTPROTO.*/"BOOTPROTO=static"/g' /etc/sysconfig/network-scripts/ifcfg-eth0
grep NETMASK /etc/sysconfig/network-scripts/ifcfg-eth0 > /dev/null
if [ $? ]; then
sed 's/^IPADDR.*/IPADDR=192.168.0.110/g' /etc/sysconfig/network-scripts/ifcfg-eth0
echo "1"
else
sed '2a IPADDR=192.168.0.110' /etc/sysconfig/network-scripts/ifcfg-eth0
echo "11"
fi
grep NETMASK /etc/sysconfig/network-scripts/ifcfg-eth0 > /dev/null
if [ $? ]; then
sed 's/^NETMASK.*/NETMASK=255.255.255.0/g' /etc/sysconfig/network-scripts/ifcfg-eth0
echo "2"
else
sed '2a NETMASK=255.255.255.0' /etc/sysconfig/network-scripts/ifcfg-eth0
echo "22"
fi
echo "3"
service network restart
fi
echo "33"

特别说明：最后一个脚本属半成品，至到上交作业前，还一直没有正确运行，主要是开头的if判断条件总是找不到正确的格式，至于代码中出现有 echo "数字" 是用来测试程序运行过程的，正确运行后将会删除。先暂时把这些交上，等明天六级过后，再解决这个问题~

本文出自 “E-guys” 博客，谢绝转载！