shell script笔记

下面记录linux里shell script学习过程中的一些笔记：

1：

根据输入名及时间信息，创建几个空文件

#!/bin/bash
#programe:
#       This program creates three files, which named by user's input and date command
#History:
#2016/4/29 dairen First release
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
#1. 让用户输入文件名
echo -e "I will use 'touch' command to creat 3 files."
read -p "filename:" fileuser

# 2. 为了避免使用者随意按 Enter,在这里检测fileuser是不是空或者未设置（bash变量设定的部分）
filename=${fileuser:-"filename"}   #详见p316

# 3. 开始利用 date 命令来取得所需要的档名
date1=$(date --date='2 days ago' +%Y%m%d)  # 前两天的日期
date2=$(date --date='1 days ago' +%Y%m%d)  # 前一天的日期
date3=$(date +%Y%m%d%H%M%S)                # 今天的日期hour minute second
file1=${filename}${date1}                  # 变量相加
file2=${filename}${date2}
file3=${filename}${date3}

# 4.
touch "$file2"                             # 创建空文件
touch "$file2"
touch "$file3"
#中文输入super+空格

man 命令是个好东西，要经常使用

2：

total=$(($firstnu*$secnu))
echo -e "\nThe result of $firstnu x $secnu is: $total"

其中对于数值运算可以：

declare -i total=$firstnu*$secnu

但是他们都不能进行小数运算，因为bash shell 里面默认支持到整数的数据

3：

test的使用

#!/bin/bash
# Program:
#       User input a filename, program will check the flowing:
#       1.) exist? 2.) file/directory? 3.) file permissions
#history:
#2016/5/3 dairen First release
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

# 1. 让使用者输入档名，并且判断使用者是否真的有输入字串？
echo -e "Please input a filename, I will check the filename's type and \
permission. \n\n"
read -p "Input a filename : " filename
test -z $filename && echo "You MUST input a filename." && exit 0
# 2. 判断文件是否存在？若不存在则显示信息并结束脚本
test ! -e $filename && echo "The filename '$filename' DO NOT exist" && exit 0
# 3. 开始判断文件类型与属性
test -f $filename && filetype="regulare file"
test -d $filename && filetype="directory"
test -r $filename && perm="readable"
test -w $filename && perm="$perm writable" #变量相加
test -x $filename && perm="$perm executable"
# 4. 开始输出资讯！
echo "The filename: $filename is a $filetype"
echo "And the permissions are : $perm"

4:

【】

#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:usr/local/sbin:~/bin

read -p "input y/n " yn
[ "$yn" ==  "y" -o "$yn" ==  "Y" ] && echo "is y" && exit 0

[ "$yn" ==  "n" -o "$yn" ==  "N" ] && echo "is n" && exit 0
echo "i don't know what your choice is"

5:

带参数的shell脚本

#!/bin/bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

echo "The script name is        ==> $0"
echo "Total parameter number is ==> $#"
[ "$#" -lt 2 ] && echo "The number of parameter is less than 2.  Stop here." \
&& exit 0
echo "Your whole parameter is   ==> '$@'"
echo "The 1st parameter         ==> $1"
echo "The 2nd parameter         ==> $2"

6:

shift来使参数变量号码偏移

#!/bin/bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

echo "Total parameter number is ==> $#"
echo "Your whole parameter is   ==> '$@'"
shift   # 进行第一次『一个变量的 shift 』
echo "Total parameter number is ==> $#"
echo "Your whole parameter is   ==> '$@'"
shift 3 # 进行第二次『三个变量的 shift 』
echo "Total parameter number is ==> $#"
echo "Your whole parameter is   ==> '$@'"

7：

netstat 查看目前主机打开的网络接口有哪些

#!/bin/bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
testing=$(netstat -tuln | grep ":80")
if [ "$testing" !=  "" ];then
echo "www is running in your system"
fi

testing=$(netstat -tuln | grep ":22")
if [ "$testing" !=  "" ];then
echo "ssh is running in your system"
fi

testing=$(netstat -tuln | grep ":21")
if [ "$testing" !=  "" ];then
echo "ftp is running in your system"
fi

testing=$(netstat -tuln | grep ":25")
if [ "$testing" !=  "" ];then
echo "mail is running in your system"
fi

testing=$(netstat -tuln | grep ":631")
if [ "$testing" !=  "" ];then
echo "cups is running in your system"
fi
exit 0

8：根据输入的date和现在的date，计算出天数

#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
echo "calculate days between two date"
read -p "inpute a date in the futere .ex>20170809" date2
stringtest=$(echo $date2 | grep '[0-9]\{8\}')
echo "$date2               $stringtest"
if [ "$stringtest" == "" ];then
echo "format wrong!!"
exit 1
fi

declare -i date_future=$(date --date="$date2" +%s)
declare -i date_now=`date +%s`
declare -i date_s=$(($date_future-$date_now))
if [ "$date_s" -lt "0" ];then
echo "your inpute date is not in the future"
else

declare -i date_days=$((date_s/60/60/24))
echo "days between now and your date is:"$date_days"."
fi

9：while do done、 until do done

#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
while [ "$testing" == "" ]
do
read -p 'inpute a number please' num
testing=$(echo $num | grep '[0-9]')
done
s=0
i=0
while [ "$i" != "$num" ]
do
s=$(($s+$i))
i=$(($i+1))
done
echo "the sum from 0-num is: $s"

10：列出指定目录下所有文件的权限

#!/bin/bash
# Program:
#       User input dir name, I find the permission of files.
# History:
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

# 1. 先看看这个目录是否存
read -p "Please input a directory: " dir
if [ "$dir" == "" -o test ! -d "$dir" ]; then
echo "The $dir is NOT exist in your system."
exit 1
fi

# 2. 开始测试文件
filelist=$(ls $dir)        # 列出所有在该目录下的文件名称
for filename in $filelist
do
perm=""
test -r "$dir/$filename" && perm="$perm readable"
test -w "$dir/$filename" && perm="$perm writable"
test -x "$dir/$filename" && perm="$perm executable"
echo "The file $dir/$filename's permission is $perm "
done

11：使用ping命令判断网络状态 seq 1 100 、 for do done、ping -c 1 -w 1 192.168.1.n

rogram
#       Use ping command to check the network's PC state.
# History
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
network="192.168.1"              # 先定义一个网域的前面部分！
for sitenu in $(seq 1 100)       # seq 为 sequence(连续) 的缩写之意
do
# 底下的程序在取得 ping 的回传值是正确的还是失败的！
#发送一次包，间隔1s，返回结果重定向到无底洞
ping -c 1 -w 1 ${network}.${sitenu} &> /dev/null && result=0 || result=1
# 开始显示结果是正确的启动 (UP) 还是错误的没有连通 (DOWN)
if [ "$result" == 0 ]; then
echo "Server ${network}.${sitenu} is UP."
else
echo "Server ${network}.${sitenu} is DOWN."
fi
done

12：

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