我的linux学习日记day6

ping
-c ping几次的意思
-i 每次的间隔
-W 最长响应时间为几秒钟

#!/bin/bash
ping -c 3 -i 0.2 -W 3 $1 &>/dev/null
#无论正确或者错误结果都输出到/dev/null  $1 用户输入的第一个参数 
if [ $? -eq  0 ]
then
echo "Host $1 is On-Line"
else
echo "Host $1 is Off-Line"
fi

[root@localhost ~]# cat /tmp/while.sh
#!/bin/bash
PRICE=$(expr $RANDOM % 1000 )
TIMES=0
while true
do
read -p "Enter:" NU
let TIMES++
if [ $NU -eq $PRICE ]
then
echo "$TIMES,Congratulations!!"
exit 0
elif [ $NU -gt $PRICE ]
then
echo "High!!!!"
else [ $NU -lt $PRICE ]
echo "Low!!!"
fi
done

-----------------------------------------------

[root@localhost tmp]# cat user.sh
#!/bin/bash
read -p "Enter The passwd:" PW
for USERNAME in `cat user.txt`
do
id $USERNAME &> /dev/null
if [ $? -eq 0 ]
then
echo "$USERNAME,already exist"
else
useradd $USERNAME &>/dev/null
echo "PW"|passwd --stdin $USERNAME &>/dev/null
fi
done

[root@system1 devops]# cat test.sh 
#!/bin/bash
read -p "Enter:" KEY
case "$KEY" in
[a-z]|[A-Z])
echo "ZiMu"
;;
[0-9])
echo "ShuZi"
;;
*)
echo "Error"
esac

计划任务

用户

useradd 

groupadd

用户权限
chmod 设置权限
chmod +权限 文件
chmod -权限 文件