shell脚本摘要

1. 开启监听端口的程序时，查看是否开启成功（该例子监听8983端口）

   #动态显示[|][/][-][\]
   function spinner() {
     local pid=$1
     local delay=0.5
     local spinstr='|/-\'
     while [ "$(ps aux | awk '{print $2}' | grep -w $pid)" ]; do
         local temp=${spinstr#?}      #'\#'从字符串开头删除匹配subString，#?删除第一个字符
         printf " [%c]  " "$spinstr"
         local spinstr=$temp${spinstr%"$temp"}  #拼出一个新的字符串：删除第一个字符，把该字符加到被删字符串的后面。%:从结尾删除匹配到的字符串
         sleep $delay
         printf "\b\b\b\b\b\b"         # \b退格键,删除显示的字符
     done
     printf "    \b\b\b\b"
   }
   
   if hash lsof 2>/dev/null ; then  # hash 查看系统中是否有该命令
     echo -n "Waiting up to 30 seconds to see Solr running on port $SOLR_PORT"
     # Launch in a subshell to show the spinner
     (loops=0
     while true
     do
       running=`lsof -PniTCP:8983 -sTCP:LISTEN`
       # 循环6次，每次sleep5秒，执行6次lsof
       if [ -z "$running" ]; then
         if [ $loops -lt 6 ]; then
   	sleep 5
   	loops=$[$loops+1]
         else
   	echo -e "Still not seeing Solr listening on $SOLR_PORT after 30 seconds!"
   	tail -30 "$SOLR_LOGS_DIR/solr.log"
   	exit # subshell!
         fi
       else
         SOLR_PID=`ps auxww | grep start\.jar | grep -w 8983 | grep -v grep | awk '{print $2}' | sort -r`
         echo -e "\nStarted Solr server on port $8983 (pid=$SOLR_PID). Happy searching!\n"
         exit # subshell!
       fi
     done) &
     spinner $!       # $!可以返回岛控制台
   else
     echo -e "NOTE: Please install lsof as this script needs it to determine if Solr is listening on port $SOLR_PORT."
     sleep 10
     SOLR_PID=`ps auxww | grep start\.jar | grep -w 8983 | grep -v grep | awk '{print $2}' | sort -r`
     echo -e "\nStarted Solr server on port $SOLR_PORT (pid=$SOLR_PID). Happy searching!\n"
     return;
   fi