Kill Rails server, a how-to guide
Short answer
If you local Rails server is running on port 3000, you have first to discover what PID is used :
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$> lsof -wni tcp:3000
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
ruby 51195 shino 10u IPv4 0x3cd31f222cb761f 0t0 TCP 127.0.0.1:hbci (LISTEN)
ruby 51195 shino 11u IPv6 0x3cd31f215db234f 0t0 TCP [::1]:hbci (LISTEN)
The column that matters is “PID”. The relevant number is 51195 here. On your computer it will probably be another number, but for our example, the solution will be
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kill -9 51195
Replace 51195 by your own PID and that’s it.
Alternative : use the shutup gem
If this is a problem that happends too frequently, you can install a gem dedicated to this problem : shutup. Repository and documentation available here
Tutorial from scratch
If you want to test the problem “from scratch”, here is a small tutorial. Ruby 3 and Rails 7 will be used.
Prerequisites
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$> ruby -v
ruby 3.0.0p0 // you need at least version 3 here
$> bundle -v
Bundler version 2.2.11
$> npm -v
8.3.0 // you need at least version 7.1 here
$> yarn -v
1.22.10
Install fresh new Rails app
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$> mkdir kill_rails && cd kill_rails
$/kill_rails> echo "source 'https://rubygems.org'" > Gemfile
$/kill_rails> echo "gem 'rails', '7.0.0'" >> Gemfile
$/kill_rails> bundle install
$/kill_rails> bundle exec rails new . --force
$/kill_rails> bundle update
$/kill_rails> bin/rails db:create
$/kill_rails> bin/rails db:migrate
Check everything is working by running
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$/kill_rails> bin/rails server
=> Booting Puma
=> Rails 7.0.0 application starting in development
=> Run `bin/rails server --help` for more startup options
Puma starting in single mode...
* Puma version: 5.5.2 (ruby 3.0.0-p0) ("Zawgyi")
* Min threads: 5
* Max threads: 5
* Environment: development
* PID: 88968
* Listening on http://127.0.0.1:3000
* Listening on http://[::1]:3000
Use Ctrl-C to stop
Side note The PID is actually displayed once in the verbose logging that appears right after you started the server. See above.
Server should run locally without error, and the default Rails page application should appear at http://localhost:3000
Now stop your local server.
Open the Gemfile and add
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gem "shutup", group: :development
Then
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$/kill_rails> bundle install
Check that the Rails server runs properly
Then restart your local Rails app
Then
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$/kill_rails> bin/rails server
=> Booting Puma
=> Rails 7.0.0 application starting in development
=> Run `bin/rails server --help` for more startup options
Puma starting in single mode...
* Puma version: 5.5.2 (ruby 3.0.0-p0) ("Zawgyi")
* Min threads: 5
* Max threads: 5
* Environment: development
* PID: 89102
* Listening on http://127.0.0.1:3000
* Listening on http://[::1]:3000
Use Ctrl-C to stop
Notice that PID has changed : now the value is 89102.
Leave your terminal window “as-is”, with the local web server running.
Kill the local Rails web server
Open another terminal window.
Given the PID we just noticed, and the 1st paragraph of this tutorial, we can type :
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$> lsof -wni tcp:3000
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
ruby 89102 shino 10u IPv4 0x3cd31f229b0f9df 0t0 TCP 127.0.0.1:hbci (LISTEN)
ruby 89102 shino 11u IPv6 0x3cd31f215db1d2f 0t0 TCP [::1]:hbci (LISTEN)
You can notice the PID is 89102, as expected
Type
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kill -9 89102
And go back to the first terminal window. You should see something like this :
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Killed: 9
$/kill_rails>
The last instruction shows that the local Rails server was actually killed.
Kill the Rails server again, using the gem
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$/kill_rails> bin/rails server
=> Booting Puma
=> Rails 7.0.0 application starting in development
=> Run `bin/rails server --help` for more startup options
Puma starting in single mode...
* Puma version: 5.5.2 (ruby 3.0.0-p0) ("Zawgyi")
* Min threads: 5
* Max threads: 5
* Environment: development
* PID: 90704
* Listening on http://127.0.0.1:3000
* Listening on http://[::1]:3000
Use Ctrl-C to stop
The PID value is now 90704.
Open another terminal window, and type
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$kill_rails> shutup
Killed process id: 90704
$kill_rails>
Ok ! what just happened is clear enough :)
Go back to the terminal window where you server was running :
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Killed: 9
$/kill_rails>
Same result as above, hopefully.
Enjoy !