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How to keep AWS Lightsail virtual server running [duplicate]

I have set up Flask on my Rapsberry Pi and I am using it for the sole purpose of acting as a server for an xml file which I created with a Python script to pass data to an iPad app (iRule).
My RPI is set up as headless and my access is with Windows 10 using PuTTY, WinSCP and TightVNC Viewer.
I run the server by opening a terminal window and the following command:
sudo python app1c.py
This sets up the server and I can access my xml file quite well. However, when I turn off the Windows machine and the PuTTY session, the Flask server shuts down!
How can I set it up so that the Flask server continues even when the Windows machine is turned off?
I read in the Flask documentation:
While lightweight and easy to use, Flask’s built-in server is not suitable for production as it doesn’t scale well and by default serves only one request at a time.
Then they go on to give examples of how to deploy your Flask application to a WSGI server! Is this necessary given the simple application I am dealing with?

Use:
$ sudo nohup python app1c.py > log.txt 2>&1 &
nohup allows to run command/process or shell script that can continue running in the background after you log out from a shell.
> log.txt: it forword the output to this file.
2>&1: move all the stderr to stdout.
The final & allows you to run a command/process in background on the current shell.

Install Node package forever at here https://www.npmjs.com/package/forever
Then use
forever start -c python your_script.py
to start your script in the background. Later you can use
forever stop your_script.py
to stop the script

You have multiple options:
Easy: deattach the process with &, for example:
$ sudo python app1c.py &
Medium: install tmux with apt-get install tmux
launch tmux and start your app as before and detach with CTRL+B.
Complexer:
Read run your flask script with a wsgi server - uwsgi, gunicorn, nginx.

Been stressing lately so I decide to go deep.
pm2 start app.py --interpreter python3
Use PM2 for things like this. I also use it for NodeJs app and a Python app on a single server.

Use:
$sudo python app1c.py >> log.txt 2>&1 &
">> log.txt" pushes all your stdout inside the log.txt file (You may check the application logs in it)
"2>&1" pushes all the stderr inside the log.txt file (This would push all the error logs inside log.txt)
"&" at the end makes it run in the background.
You would get the process id immediately after executing this command with which you can monitor or verify it.
$sudo ps -ef | grep <process-id>
Hope it helps..!!

You can always use nohup to run any scripts as background process.
nohup python script.py
This will run your script in background and also have its logs appended in nohup.out file which will be located in the directory script.py is store.
Make sure, you close the terminal and not press Ctrl + C. This will allow it to run in background even when you log out.
To stop it from running , ssh in to the pi again and run ps -ef |grep nohup and kill -9 XXXXX
where XXXX is the pid you will get ps command.

I've always found a detached screen process to be best for use cases such as these.
Run:
screen -m -d sudo python app1c.py

I was trying to run my flask app for testing in my GitHub CI and the step where I was running the app was getting stuck for ever. The reason was that it was never releasing the command line
Best solution I found was a combination of two other responses in here:
nohup python script.py &

Stopping Django's Server [duplicate]

So im using ruby on rails in windows (i hear you all spitting your coffee onto the screen), its only a short term thing. (using ubuntu at home) So i tried to fire up webrick this afternoon and i get the error message
TCPServer Error, only one usage of each socket address is normally permitted
So it seems as if port 3000 is still running from last week? My question is how do i kill the process from the Windows command line. normally i have to press ctrl and pause/break in windows as ctrl c is not working which is only killing the batch process it seems..
Any solutions welcomed
Edit
So it seems as if
tasklist
will give me the list of processes, but where do i find the process for running the webrick server?
ruby.exe is not listed as a running process

Try using netstat -a -o -n to determine the pid of the process running on port 3000. Then you should be able to use taskkill /pid #### to kill whatever process is running on that port.
Probably not the most graceful way to do it, but I think it should work.
EDIT
You'll probably have to also use the /F flag to force-kill the process. I just tried it on my local machine, and that worked fine.

Go into rails_project\tmp\pids and delete the .pid file in there.
run:
rails server

How to run Flask Server in the background

I have set up Flask on my Rapsberry Pi and I am using it for the sole purpose of acting as a server for an xml file which I created with a Python script to pass data to an iPad app (iRule).
My RPI is set up as headless and my access is with Windows 10 using PuTTY, WinSCP and TightVNC Viewer.
I run the server by opening a terminal window and the following command:
sudo python app1c.py
This sets up the server and I can access my xml file quite well. However, when I turn off the Windows machine and the PuTTY session, the Flask server shuts down!
How can I set it up so that the Flask server continues even when the Windows machine is turned off?
I read in the Flask documentation:
While lightweight and easy to use, Flask’s built-in server is not suitable for production as it doesn’t scale well and by default serves only one request at a time.
Then they go on to give examples of how to deploy your Flask application to a WSGI server! Is this necessary given the simple application I am dealing with?

Use:
$ sudo nohup python app1c.py > log.txt 2>&1 &
nohup allows to run command/process or shell script that can continue running in the background after you log out from a shell.
> log.txt: it forword the output to this file.
2>&1: move all the stderr to stdout.
The final & allows you to run a command/process in background on the current shell.

Install Node package forever at here https://www.npmjs.com/package/forever
Then use
forever start -c python your_script.py
to start your script in the background. Later you can use
forever stop your_script.py
to stop the script

You have multiple options:
Easy: deattach the process with &, for example:
$ sudo python app1c.py &
Medium: install tmux with apt-get install tmux
launch tmux and start your app as before and detach with CTRL+B.
Complexer:
Read run your flask script with a wsgi server - uwsgi, gunicorn, nginx.

Been stressing lately so I decide to go deep.
pm2 start app.py --interpreter python3
Use PM2 for things like this. I also use it for NodeJs app and a Python app on a single server.

Use:
$sudo python app1c.py >> log.txt 2>&1 &
">> log.txt" pushes all your stdout inside the log.txt file (You may check the application logs in it)
"2>&1" pushes all the stderr inside the log.txt file (This would push all the error logs inside log.txt)
"&" at the end makes it run in the background.
You would get the process id immediately after executing this command with which you can monitor or verify it.
$sudo ps -ef | grep <process-id>
Hope it helps..!!

You can always use nohup to run any scripts as background process.
nohup python script.py
This will run your script in background and also have its logs appended in nohup.out file which will be located in the directory script.py is store.
Make sure, you close the terminal and not press Ctrl + C. This will allow it to run in background even when you log out.
To stop it from running , ssh in to the pi again and run ps -ef |grep nohup and kill -9 XXXXX
where XXXX is the pid you will get ps command.

I've always found a detached screen process to be best for use cases such as these.
Run:
screen -m -d sudo python app1c.py

I was trying to run my flask app for testing in my GitHub CI and the step where I was running the app was getting stuck for ever. The reason was that it was never releasing the command line
Best solution I found was a combination of two other responses in here:
nohup python script.py &

Python in Raspberry socket.error: [Errno 98] Address already in use when creating socket [duplicate]

In my Python socket program, I sometimes need to interrupt it with Ctrl-C. When I do this, it does close the connection using socket.close().
However, when I try to reopen it I have to wait what seems like a minute before I can connect again. How does one correctly close a socket? Or is this intended?

Yes, it is intended. Here you can read detailed explanation. It is possible to override this behavior by setting SO_REUSEADDR option on a socket. For example:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

$ ps -fA | grep python
501 81211 12368 0 10:11PM ttys000 0:03.12
python -m SimpleHTTPServer
$ kill 81211

This happens because you trying to run service at the same port and there is an already running application.
it can happen because your service is not stopped in the process stack. you just have to kill those processes.
There is no need to install anything here is the one line command to kill all running python processes.
for Linux based OS:
Bash:
kill -9 $(ps -A | grep python | awk '{print $1}')
Fish:
kill -9 (ps -A | grep python | awk '{print $1}')

If you use a TCPServer, UDPServer or their subclasses in the socketserver module, you can set this class variable (before instantiating a server):
socketserver.TCPServer.allow_reuse_address = True
(via SocketServer.ThreadingTCPServer - Cannot bind to address after program restart )
This causes the init (constructor) to:
if self.allow_reuse_address:
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

Nothing worked for me except running a subprocess with this command, before calling HTTPServer(('', 443), myHandler):
kill -9 $(lsof -ti tcp:443)
Of course this is only for linux-like OS!

A simple solution that worked for me is to close the Terminal and restart it.

For Linux,
ps aux | grep python
This will show you the error. The process number (eg.35225) containing your python file is the error.
Now,
sudo kill -9 35225
This will kill the error process and your problem will be solved.

First of all find the python process ID using this command
ps -fA | grep python
You will get a pid number by naming of your python process on second column
Then kill the process using this command
kill -9 pid

run the command
fuser -k (port_number_you_are _trying_to_access)/TCP
example for flask: fuser -k 5000/tcp
Also, remember this error arises when you interput by ctrl+z. so to terminate use ctrl+c

I faced similar error at odoo server and resolved that with these simple following steps:
Paste following code in terminal
ps -fA | grep python
You will get a pid number. Now copy the pid number from second column of terminal output.
Then write as below
kill -9 pid
The terminal will restart and then the command
flask run
Will work fine!
Thank you

Do nothing just wait for a couple of minutes and it will get resolved. It happens due to the slow termination of some processes, and that's why it's not even showing in the running processes list.

I had the same problem (Err98 Address already in use) on a Raspberry Pi running python for a EV charging manager for a Tesla Wall Connector. The software had previously been fine but it stopped interrogating the solar inverter one day and I spent days thinking it was something I'd done in python. Turns out the root cause was the Wifi modem assigning a new dynamic IP to the solar inverter as as result of introducing a new smart TV into my home. I changed the python code to reflect the new IP address that I found from the wifi modem and bingo, the issue was fixed.

Got this error after I ran my code while programming a Pico W via Thonny. At the command line just do a socket.reset() to clear the issue.
>>> socket.reset()

The cleanest way to make the socket immediately reusable is to follow the recommendation to first shutdown the client end (socket) of a connection, and make sure the server's end shuts down last (through exception handling if needed).
This might well mean that the server end runs forever.
This is not a problem if that "forever" loop pauses execution, e.g. read from socket.
How you "break" that "forever" loop is up to you as server admin, as long as there are no clients (apart from obvious system level exceptions)

I tried the following code to settle the issue:
sudo lsof -t -i tcp:8000 | xargs kill -9

sudo pkill -9 python
try this command

Python [Errno 98] Address already in use

In my Python socket program, I sometimes need to interrupt it with Ctrl-C. When I do this, it does close the connection using socket.close().
However, when I try to reopen it I have to wait what seems like a minute before I can connect again. How does one correctly close a socket? Or is this intended?

Yes, it is intended. Here you can read detailed explanation. It is possible to override this behavior by setting SO_REUSEADDR option on a socket. For example:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

$ ps -fA | grep python
501 81211 12368 0 10:11PM ttys000 0:03.12
python -m SimpleHTTPServer
$ kill 81211

This happens because you trying to run service at the same port and there is an already running application.
it can happen because your service is not stopped in the process stack. you just have to kill those processes.
There is no need to install anything here is the one line command to kill all running python processes.
for Linux based OS:
Bash:
kill -9 $(ps -A | grep python | awk '{print $1}')
Fish:
kill -9 (ps -A | grep python | awk '{print $1}')

If you use a TCPServer, UDPServer or their subclasses in the socketserver module, you can set this class variable (before instantiating a server):
socketserver.TCPServer.allow_reuse_address = True
(via SocketServer.ThreadingTCPServer - Cannot bind to address after program restart )
This causes the init (constructor) to:
if self.allow_reuse_address:
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

Nothing worked for me except running a subprocess with this command, before calling HTTPServer(('', 443), myHandler):
kill -9 $(lsof -ti tcp:443)
Of course this is only for linux-like OS!

A simple solution that worked for me is to close the Terminal and restart it.

For Linux,
ps aux | grep python
This will show you the error. The process number (eg.35225) containing your python file is the error.
Now,
sudo kill -9 35225
This will kill the error process and your problem will be solved.

First of all find the python process ID using this command
ps -fA | grep python
You will get a pid number by naming of your python process on second column
Then kill the process using this command
kill -9 pid

run the command
fuser -k (port_number_you_are _trying_to_access)/TCP
example for flask: fuser -k 5000/tcp
Also, remember this error arises when you interput by ctrl+z. so to terminate use ctrl+c

I faced similar error at odoo server and resolved that with these simple following steps:
Paste following code in terminal
ps -fA | grep python
You will get a pid number. Now copy the pid number from second column of terminal output.
Then write as below
kill -9 pid
The terminal will restart and then the command
flask run
Will work fine!
Thank you

Do nothing just wait for a couple of minutes and it will get resolved. It happens due to the slow termination of some processes, and that's why it's not even showing in the running processes list.

I had the same problem (Err98 Address already in use) on a Raspberry Pi running python for a EV charging manager for a Tesla Wall Connector. The software had previously been fine but it stopped interrogating the solar inverter one day and I spent days thinking it was something I'd done in python. Turns out the root cause was the Wifi modem assigning a new dynamic IP to the solar inverter as as result of introducing a new smart TV into my home. I changed the python code to reflect the new IP address that I found from the wifi modem and bingo, the issue was fixed.

Got this error after I ran my code while programming a Pico W via Thonny. At the command line just do a socket.reset() to clear the issue.
>>> socket.reset()

The cleanest way to make the socket immediately reusable is to follow the recommendation to first shutdown the client end (socket) of a connection, and make sure the server's end shuts down last (through exception handling if needed).
This might well mean that the server end runs forever.
This is not a problem if that "forever" loop pauses execution, e.g. read from socket.
How you "break" that "forever" loop is up to you as server admin, as long as there are no clients (apart from obvious system level exceptions)

I tried the following code to settle the issue:
sudo lsof -t -i tcp:8000 | xargs kill -9

sudo pkill -9 python
try this command