【案例分析】Linux下怎样查看port占用情况

时间：2023-03-09 03:30:36
【案例分析】Linux下怎样查看port占用情况 
  作者：zhanhailiang 日期：2014-11-08

基于express写一个測试server代码例如以下，可是执行失败，报“listen EADDRINUSE”。字面上理解是error address in use，说明当前你监听的port3000已经被使用了：

[root@~/wade/wadetest]# cat index.js

var express = require('express');

var app = express();

 

app.get('/', function(req, res){

  res.send('hello world');

});

 

app.listen(3000, function() {

 

});

[root@~/wade/wadetest]# node index.js

 

events.js:72

        throw er; // Unhandled 'error' event

              ^

Error: listen EADDRINUSE

    at errnoException (net.js:904:11)

    at Server._listen2 (net.js:1042:14)

    at listen (net.js:1064:10)

    at Server.listen (net.js:1138:5)

    at EventEmitter.app.listen (/root/wade/wadetest/node_modules/express/lib/application.js:559:24)

    at Object.<anonymous> (/root/wade/wadetest/index.js:8:5)

    at Module._compile (module.js:456:26)

    at Object.Module._extensions..js (module.js:474:10)

    at Module.load (module.js:356:32)

    at Function.Module._load (module.js:312:12)

尝试使用netstat查看当前机器port占用情况：

[root@~]# netstat -anop

Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name    Timer

tcp        0      0 0.0.0.0:6379                0.0.0.0:*                   LISTEN      5906/redis-server * off (0.00/0/0)

tcp        0      0 127.0.0.1:11211             0.0.0.0:*                   LISTEN      8023/memcached      off (0.00/0/0)

tcp        0      0 0.0.0.0:6380                0.0.0.0:*                   LISTEN      26815/redis-server  off (0.00/0/0)

tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN      2720/nginx          off (0.00/0/0)

tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      23854/sshd          off (0.00/0/0)

tcp        0      0 0.0.0.0:3000                0.0.0.0:*                   LISTEN      6732/node           off (0.00/0/0)

tcp        0      0 127.0.0.1:9000              0.0.0.0:*                   LISTEN      2466/php-fpm        off (0.00/0/0)

tcp        0      0 0.0.0.0:3690                0.0.0.0:*                   LISTEN      25447/svnserve      off (0.00/0/0)

tcp        0      0 0.0.0.0:3306                0.0.0.0:*                   LISTEN      23376/mysqld        off (0.00/0/0)

当中：

-n, --numeric              don't resolve names

-p, --programs             display PID/Program name for sockets

-a, --all, --listening     display all sockets (default: connected)

-o, --timers               display timers

由上可见。port3000被PID为6732的node进程占用。

接下来通过ps查询该进程的具体信息：

[root@~]# ps -f -p 6732

UID        PID  PPID  C STIME TTY          TIME CMD

root      6732  6703  0 Nov02 ?        00:00:00 node /root/wade/git/node-lessons/lesson1/app.js

[root@~/wade/wadetest]# ps -fp 6703

UID        PID  PPID  C STIME TTY          TIME CMD

root      6703     1  0 Nov02 ?        00:00:00 pm2: Daemon

当中：

-f full 表示输出进程完整信息，如上所看到的

-p by process ID 表示查询指定进程ID

最后。kill掉进程6703或停止pm2服务就可以正常执行上面的node演示样例：

[root@~/wade/git/node-lessons/lesson1]# pm2 kill

[PM2] Stopping PM2...

[PM2] Deleting all process

[PM2] deleteProcessId process id 0

[PM2] All processes has been stopped and deleted

[PM2] PM2 stopped

[root@~/wade/wadetest]# node index.js

例如以下图：

【案例分析】Linux下怎样查看port占用情况

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