函数语法案例

函数语法案例1
一、rsync启停脚本（函数）
1) 脚本

cat /server/scripts/b6.sh
#!/bin/sh
# chkconfig: 2345 20 80
# description:rsyncd start up scripts by noah.
. /etc/init.d/functions
function usage () {
    echo $"usage:$0{start|stop|restart}"
    exit 1
}
function start () {
     rsync --daemon
     sleep 1
     if [ `netstat -lntup|grep rsync|wc -l` -ge 1 ]
       then
         action "rsyncd is started." /bin/true
     else
         action "rsyncd is started." /bin/false
     fi
}
function stop () {
     pkill rsync &>/dev/null
     sleep 2
     if [ `netstat -lntup|grep rsync|wc -l` -eq 0 ]
       then
         action "rsyncd is stopped." /bin/true
     else
         action "rsyncd is stopped." /bin/false
     fi
}
function main () {
  if [ $# -ne 1 ]
    then
      usage
  fi
  if [ "$1" = "start" ]
    then
      start
   elif [ "$1" = "stop" ]
     then
       stop
   elif [ "$1" = "restart" ]
     then
       stop
       sleep 2
       start
   else
       usage
fi
}
main $*

2) 执行结果：

sh /server/scripts/b6.sh stop
rsyncd is stopped. [确定]
sh /server/scripts/b6.sh start
Failed to parse config file: /etc/rsyncd.conf
rsyncd is started. [失败]

函数语法案例2
一、函数传参测试网址异常

1. 基本实现
   1) 代码

   cat /server/scripts/b5.sh
   #!/bin/bash
   function usage () {
   echo "usage:$0 input one url"
   exit 1
   }
   #错误提示函数
   function check_url () {
   wget --spider -q -o /dev/null --tries=1 -T 5 $1
   if [ $? -eq 0 ]
    then
      echo "$1 is yes."
   else
      echo "$1 is no."
   fi
   }
   #url测试函数，注意$1
   function main () {
   if [ $# -ne 1 ]
    then
      usage
   fi
   check_url $1
   }
   #主函数，先判断参数个数，不符合要求调用错误提示函数提示，符合要求的话，调用check_url函数并把$1传递给函数
   main $*
   #这是将命令行接受到的所有参数，作为函数参数传递给函数内部的一种常用手法

   2) 执行情况

   sh /server/scripts/b5.sh www.baidu.com
   www.baidu.com is yes.
   sh /server/scripts/b5.sh www.baidu.co
   www.baidu.co is no.
   sh /server/scripts/b5.sh www.baidu.com abc.com
   usage:/server/scripts/b5.sh input one url

2. 改为命令行传参
   1) 脚本

   cat /server/scripts/b5.sh
   #!/bin/bash
   [ -f /etc/init.d/functions ] && . /etc/init.d/functions || exit 1
   function usage () {
   echo "usage:$0 input one url"
   exit 1
   }
   function check_url () {
   wget --spider -q -o /dev/null --tries=1 -T 5 $1
   if [ $? -eq 0 ]
    then
      action "$1 is yes." /bin/true   
   else
      action "$1 is no." /bin/false
   fi
   }
   function main () {
   if [ $# -ne 1 ]
    then
      usage
   fi
   check_url $1
   }
   main $*

   2) 执行结果

   sh /server/scripts/b5.sh www.baidu.com
   www.baidu.com is yes. [确定]
   sh /server/scripts/b5.sh www.baidu.co
   www.baidu.co is no. [失败]