shell script筆記

下面記錄linux裡shell script學習過程中的一些筆記：

1：

根據輸入名及時間信息，創建幾個空文件

#!/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. 讓用戶輸入文件名
echo -e "I will use 'touch' command to creat 3 files."
read -p "filename:" fileuser

# 2. 為了避免使用者隨意按 Enter,在這裡檢測fileuser是不是空或者未設置（bash變量設定的部分）
filename=${fileuser:-"filename"}   #詳見p316

# 3. 開始利用 date 命令來取得所需要的檔名
date1=$(date --date='2 days ago' +%Y%m%d)  # 前兩天的日期
date2=$(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}${date1}                  # 變量相加
file2=${filename}${date2}
file3=${filename}${date3}

# 4. 
touch "$file2"                             # 創建空文件
touch "$file2"
touch "$file3"
#中文輸入super+空格

man 命令是個好東西，要經常使用2：

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

其中對於數值運算可以：

declare -i total=$firstnu*$secnu

但是他們都不能進行小數運算，因為bash shell 裡面默認支持到整數的數據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. 讓使用者輸入檔名，並且判斷使用者是否真的有輸入字串？
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. 判斷文件是否存在？若不存在則顯示信息並結束腳本
test ! -e $filename && echo "The filename '$filename' DO NOT exist" && exit 0
# 3. 開始判斷文件類型與屬性
test -f $filename && filetype="regulare file"
test -d $filename && filetype="directory"
test -r $filename && perm="readable"
test -w $filename && perm="$perm writable" #變量相加
test -x $filename && perm="$perm executable"
# 4. 開始輸出資訊！
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:

帶參數的shell腳本

#!/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來使參數變量號碼偏移

#!/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   # 進行第一次『一個變量的 shift 』
echo "Total parameter number is ==> $#"
echo "Your whole parameter is   ==> '$@'"
shift 3 # 進行第二次『三個變量的 shift 』
echo "Total parameter number is ==> $#"
echo "Your whole parameter is   ==> '$@'"

7：

netstat 查看目前主機打開的網絡接口有哪些

#!/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：根據輸入的date和現在的date，計算出天數

#!/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：列出指定目錄下所有文件的權限

#!/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. 先看看這個目錄是否存
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. 開始測試文件
filelist=$(ls $dir)        # 列出所有在該目錄下的文件名稱
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命令判斷網絡狀態 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"              # 先定義一個網域的前面部分！
for sitenu in $(seq 1 100)       # seq 為 sequence(連續) 的縮寫之意
do
        # 底下的程序在取得 ping 的回傳值是正確的還是失敗的！
        #發送一次包，間隔1s，返回結果重定向到無底洞
        ping -c 1 -w 1 ${network}.${sitenu} &> /dev/null && result=0 || result=1
        # 開始顯示結果是正確的啟動 (UP) 還是錯誤的沒有連通 (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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