Bash Shell 小功能实现收集

 

 判断命令执行后的返回值

• 执行一个命令后，会有相应的返回值，表示该命令执行的情况
• 脚本中捕获命令执行后的返回值
  

  # hello 是一本不存在的命令或者脚本
  hello
  
  if [ 127 -eq $? ]; then
          echo '127 -ne ~'
  fi

  View Code

   

 

判断参数是否为空

• 参数不能为空
  

  if [ -z "$*" ]; then
          echo -e "\tWarning: must has option. Please run with '-h' get help informations.\n"
          exit 1
  fi

  View Code

  判断时，双引号不能少 

   

 

判断当前用户是不是 root

• 判断当前用户，不是 root 就退出
  

  if [ "root" == $(whoami) ]; then
          echo $(whoami)
  else
          echo -e "  Please login with root privlegess.\n"
          exit 2
  fi

  View Code

  适用必须是 root 的场合

   
• check for root user to use script
  

  #check for root user
  if [ "$(id -u)" -ne 0 ] ; then
          echo "You must run this script as root. Sorry!"
          exit 1
  fi

  View Code

   

 

Bash Shell 的参数扩展

• 三个选项，一个无参，两个有参
  

  while getopts ":g:s:h" opt; do
  
      case "$opt" in
          # Valid options.
          "g")
              echo -e "\tPackage Name: $OPTARG."
                  get $OPTARG
              ;;
          "s")
                  echo -e "\tPackage Name: $OPTARG."
                  set $OPTARG
              ;;
          "h")
                  help
                  ;;
          ":")    # Silent, without arg
              echo -e "\tOption $OPTARG has't parameter."
              ;;
          "?")    # Not silent, without arg. And invalid option.
              echo -e "\tInvalid option $OPTARG."
              ;;
          "*")    # Impossible to implement.
              echo -e "\tunkown error from arg."
              ;;
      esac
  done

  View Code

   

 

服务托管

• sysv
  

  #! /bin/bash
  #
  # Daemo up/down
  #
  # chkconfig: 35 10 90
  # description: start at boot time.
  #
  
  PID=
  
  case "$1" in
    start)
      /usr/local/redis/bin/redis-server /usr/local/redis/redis.conf &>/dev/null
      PID=$(pidof redis-server)
      echo $PID
      ;;
    stop)
      ;;
    status)
      echo "你来写？牛的不行！"
      ;;
    restart|reload|force-reload)
      ;;
    *)
          echo $"Usage: $0 {start}"
  esac
  exit 1

  View Code

  托管的思想：就是在控制服务启动的脚本文件中添加 【

  # chkconfig: 35 10 90
  # description: start at boot time.

  】 这么两行内容，chkconfig 指定了启动的级别（35），启动顺序，关闭顺序。description 作为脚本的功能描述。