サーバースタートしたらエラー

miyajimayuki@miyajimayuukinoMacBook-Pro web_tech % ruby test.rb
[2020-03-17 14:25:54] INFO  WEBrick 1.4.2
[2020-03-17 14:25:54] INFO  ruby 2.6.3 (2019-04-16) [x86_64-darwin19]
Traceback (most recent call last):
	11: from test.rb:2:in `<main>'
	10: from test.rb:2:in `new'
	 9: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/webrick/httpserver.rb:47:in `initialize'
	 8: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/webrick/server.rb:108:in `initialize'
	 7: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/webrick/server.rb:127:in `listen'
	 6: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/webrick/utils.rb:65:in `create_listeners'
	 5: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/socket.rb:762:in `tcp_server_sockets'
	 4: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/socket.rb:227:in `foreach'
	 3: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/socket.rb:227:in `each'
	 2: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/socket.rb:764:in `block in tcp_server_sockets'
	 1: from /Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/socket.rb:201:in `listen'
/Users/miyajimayuki/.rbenv/versions/2.6.3/lib/ruby/2.6.0/socket.rb:201:in `bind': Address already in use - bind(2) for 0.0.0.0:3000 (Errno::EADDRINUSE)

原因

サーバーをcontrol + Zで切ったら次にサーバーを立ち上げるとエラーになるようです。

解決

いま動いているport: 3000のサーバーをターミナルに出力して

% lsof -i:3000

COMMAND  PID         USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
ruby    2054 miyajimayuki   10u  IPv6 0xb15f9119d06b6d43      0t0  TCP *:hbci (LISTEN)
ruby    2054 miyajimayuki   11u  IPv4 0xb15f9119cf61f0cb      0t0  TCP *:hbci (LISTEN)

下記コマンドでプロセスを切る

% kill -9 {PID}

履歴

COMMAND  PID         USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
ruby    2054 miyajimayuki   10u  IPv6 0xb15f9119d06b6d43      0t0  TCP *:hbci (LISTEN)
ruby    2054 miyajimayuki   11u  IPv4 0xb15f9119cf61f0cb      0t0  TCP *:hbci (LISTEN)
miyajimayuki@miyajimayuukinoMacBook-Pro web_tech % kill -9 2054
miyajimayuki@miyajimayuukinoMacBook-Pro web_tech % 
[1]  + killed     ruby test.rb

プロセスが切れたので再度サーバーが起動できるようになりました！

miyajimayuki@miyajimayuukinoMacBook-Pro web_tech % ruby test.rb
[2020-03-17 14:32:34] INFO  WEBrick 1.4.2
[2020-03-17 14:32:34] INFO  ruby 2.6.3 (2019-04-16) [x86_64-darwin19]
[2020-03-17 14:32:34] INFO  WEBrick::HTTPServer#start: pid=2126 port=3000

以上です！