Shell指令碼初步學習

Shell指令碼初步學習    Shell指令碼對於Linux下的系統管理員和營運的人來說很重要。最近看了一下Shell指令碼，為了系統地學習一下Shell指令碼，我看了一下《鳥哥的Linux私房菜基礎學習篇》第三版，其中的第13章講了一下Shell script的學習。    編寫shell script的良好習慣 1、script的功能；2、script的版本資訊；3、script的作者與聯絡方式；4、script的版本聲明方式；5、script的History  （記錄)6、script內較特殊的命令，使用“絕對路徑”的方式來執行；7、script執行時需要的環境變數預先聲明和設定。     sh01.sh [plain] <span style="font-size:14px;">#!/bin/bash  # program:  #   This program show "Hello World!" in your screen  # History:  # 2013/04/21 15:31 ccf First release  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  export PATH  echo -e "Hello World! \a \n"  exit 0  </span>  sh02.sh [plain] <span style="font-size:14px;">#!/bin/bash  # Program  #   User inputs his first name and last name.   Program shows his full name.  # History  # 2013/04/21,by ccf,First release  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  export PATH      read -p "Please input your first name: " firstname   # 提示使用者輸入  read -p "Please input your last name:  " lastname    # 提示使用者輸入  echo -e "\nYour full name is: $firstname $lastname"   #結果由螢幕輸出</span>  sh03.sh [plain] <span style="font-size:14px;">#!/bin/bash  # Program  #   Program creates three files, which named by user's input  #   and date command  # History:  # 2013/04/21 Sunday ccf First release  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/loacl/sbin:~/bin  export PATH    # 1.讓使用者輸入檔案名稱，並取得fileuser這個變數  echo -e "I will use 'touch' command to create 3 files." # 純粹顯示資訊  read -p "Please input your filename: " fileuser         # 提示使用者輸入    # 2.為了避免使用者隨意按【Enter】,利用變數功能分析檔案名稱是否有設定  filename=${fileuser:-"filename"}                        # 開始判斷是否有設定檔名    # 3.開始利用date命令來取得所需要的檔案名稱了  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=$(date +%Y%m%d)                        # 今天的日期  file1=${filename}${date1}              # 下面三行在設定檔名  file2=${filename}${date2}  file3=${filename}${date3}    # 4.建立檔案名稱  touch "$file1"  touch "$file2"  touch "$file3"  </span>   sh04.sh[plain] <span style="font-size:14px;">#!/bin/bash  # Program:  #   User inputs 2 integer numbers; program will cross these two numbers.  # History:  # 2013/04/21 ccf19881030  First release  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  export PATH  echo -e "You should input 2 numbers, I will cross them!\n"  read -p "first number: "  firstnum  read -p "second number: " secondnum  total=$(($firstnum * $secondnum))  echo -e "\nThe result of $firstnum * $secondnum is ==> $total"</span>   sh05.sh[plain] <span style="font-size:14px;">#!/bin/bash  #program:  #   User input a filename, program will check the follwing:  #   1.) exist? 2.) file/directory? 3.) file permissions  #History:  # 2013/05/14 ccf First Release  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  export PATH    #1、讓使用者輸入檔案名稱,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"  #純粹顯示資訊  read -p "Input a filename : " filename       #提示使用者輸入    test -z $filename && echo "You MUST input a filename." && exit 0    #2、判斷檔案是否存在，若不存在則顯示資訊並結束指令碼  test ! -e $filename && echo "The filename '$filename' DO NOT exist" && exit 0    #3、開始判斷檔案類型和屬性  test -f $filename && filetype="regular file"  test -d $filename && filetype="directory"  test -r $filename && perm="readable"  test -w $filename && perm="$perm writeable"  test -x $filename && perm="$perm executable"    #4、開始輸出資訊！  echo "The filename: $filename is a $filetype"  echo "And the permission are : $perm"  </span>  sh06.sh  [plain] #!/bin/bash  # Program:  #     This program shows the user's choice  # History:  # 2013/05/14 ccf First release  PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  export PATH    read -p "Please input (Y/N) : " yn  [ "$yn" == "Y" -o "$yn" == "y" ] && echo "OK, continue" && exit 0  [ "$yn" == "N" -o "$yn" == "n" ] && echo "Oh, interrupt!" && exit 0  echo "I don't know what your choice is" && exit 0   可以通過sh sh01.sh或者chmod a+x sh01.sh;./sh01.sh來執行shell指令碼。