CODEWITHSUNDEEP
node.jslinuxbackground-process
murvinlai
murvinlai

Reputation: 50375

How to run Node.js as a background process and never die?

I connect to the linux server via putty SSH. I tried to run it as a background process like this:

$ node server.js &

However, after 2.5 hrs the terminal becomes inactive and the process dies. Is there anyway I can keep the process alive even with the terminal disconnected?

Edit 1

Actually, I tried nohup, but as soon as I close the Putty SSH terminal or unplug my internet, the server process stops right away.

Is there anything I have to do in Putty?

Edit 2 (on Feb, 2012)

There is a node.js module, forever. It will run node.js server as daemon service.

Upvotes: 505

Views: 768940

Answers (14)

Victor Schröder
Victor Schröder

Reputation: 7767

This is an old question, but is high ranked on Google. I almost can't believe on the highest voted answers, because running a node.js process inside a screen session, with the & or even with the nohup flag -- all of them -- are just workarounds.

Specially the screen/tmux solution, which should really be considered an amateur solution. Screen and Tmux are not meant to keep processes running, but for multiplexing terminal sessions. It's fine, when you are running a script on your server and want to disconnect. But for a node.js server your don't want your process to be attached to a terminal session. This is too fragile. To keep things running you need to daemonize the process!

There are plenty of good tools to do that.

PM2: http://pm2.keymetrics.io/

# basic usage
$ npm install pm2 -g
$ pm2 start server.js

# you can even define how many processes you want in cluster mode:
$ pm2 start server.js -i 4

# you can start various processes, with complex startup settings
# using an ecosystem.json file (with env variables, custom args, etc):
$ pm2 start ecosystem.json

One big advantage I see in favor of PM2 is that it can generate the system startup script to make the process persist between restarts:

$ pm2 startup [platform]

Where platform can be ubuntu|centos|redhat|gentoo|systemd|darwin|amazon.

forever.js: https://github.com/foreverjs/forever

# basic usage
$ npm install forever -g
$ forever start app.js

# you can run from a json configuration as well, for
# more complex environments or multi-apps
$ forever start development.json

Init scripts:

I'm not go into detail about how to write a init script, because I'm not an expert in this subject and it'd be too long for this answer, but basically they are simple shell scripts, triggered by OS events. You can read more about this here

Docker:

Just run your server in a Docker container with -d option and, voilá, you have a daemonized node.js server!

Here is a sample Dockerfile (from node.js official guide):

FROM node:argon

# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

# Install app dependencies
COPY package.json /usr/src/app/
RUN npm install

# Bundle app source
COPY . /usr/src/app

EXPOSE 8080
CMD [ "npm", "start" ]

Then build your image and run your container:

$ docker build -t <your username>/node-web-app .
$ docker run -p 49160:8080 -d <your username>/node-web-app

Always use the proper tool for the job. It'll save you a lot of headaches and over hours!

Upvotes: 144

MK.
MK.

Reputation: 34587

Simple solution (if you are not interested in coming back to the process, just want it to keep running): 

nohup node server.js &

There's also the jobs command to see an indexed list of those backgrounded processes. And you can kill a backgrounded process by running kill %1 or kill %2 with the number being the index of the process.

Powerful solution (allows you to reconnect to the process if it is interactive): 

screen

You can then detach by pressing Ctrl+a+d and then attach back by running screen -r

Also consider the newer alternative to screen, tmux.

Upvotes: 532

Alex Povar
Alex Povar

Reputation: 4960

You really should try to use screen. It is a bit more complicated than just doing nohup long_running &, but understanding screen once you never come back again.

Start your screen session at first:

user@host:~$ screen

Run anything you want:

wget http://mirror.yandex.ru/centos/4.6/isos/i386/CentOS-4.6-i386-binDVD.iso

Press ctrl+A and then d. Done. Your session keeps going on in background.

You can list all sessions by screen -ls, and attach to some by screen -r 20673.pts-0.srv command, where 0673.pts-0.srv is an entry list.

Upvotes: 140

Hunter Frazier
Hunter Frazier

Reputation: 477

Try this for a simple solution

cmd & exit

Upvotes: 0

David Lopes
David Lopes

Reputation: 559

For Ubuntu i use this:

(exec PROG_SH &> /dev/null &)

regards

Upvotes: 3

Krzysztof Księżyk
Krzysztof Księżyk

Reputation: 1399

Apart from cool solutions above I'd mention also about supervisord and monit tools which allow to start process, monitor its presence and start it if it died. With 'monit' you can also run some active checks like check if process responds for http request

Upvotes: 3

user3132194
user3132194

Reputation: 2567

To run command as a system service on debian with sysv init:

Copy skeleton script and adapt it for your needs, probably all you have to do is to set some variables. Your script will inherit fine defaults from /lib/init/init-d-script, if something does not fits your needs - override it in your script. If something goes wrong you can see details in source /lib/init/init-d-script. Mandatory vars are DAEMON and NAME. Script will use start-stop-daemon to run your command, in START_ARGS you can define additional parameters of start-stop-daemon to use.

cp /etc/init.d/skeleton /etc/init.d/myservice
chmod +x /etc/init.d/myservice
nano /etc/init.d/myservice

/etc/init.d/myservice start
/etc/init.d/myservice stop

That is how I run some python stuff for my wikimedia wiki:

...
DESC="mediawiki articles converter"
DAEMON='/home/mss/pp/bin/nslave'
DAEMON_ARGS='--cachedir /home/mss/cache/'
NAME='nslave'
PIDFILE='/var/run/nslave.pid'
START_ARGS='--background --make-pidfile --remove-pidfile --chuid mss --chdir /home/mss/pp/bin'

export PATH="/home/mss/pp/bin:$PATH"

do_stop_cmd() {
    start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 \
        $STOP_ARGS \
        ${PIDFILE:+--pidfile ${PIDFILE}} --name $NAME
    RETVAL="$?"
    [ "$RETVAL" = 2 ] && return 2
    rm -f $PIDFILE
    return $RETVAL
}

Besides setting vars I had to override do_stop_cmd because of python substitutes the executable, so service did not stop properly.

Upvotes: 3

Donald Derek
Donald Derek

Reputation: 2597

Nohup and screen offer great light solutions to running Node.js in the background. Node.js process manager (PM2) is a handy tool for deployment. Install it with npm globally on your system:

npm install pm2 -g

to run a Node.js app as a daemon:

pm2 start app.js

You can optionally link it to Keymetrics.io a monitoring SAAS made by Unitech.

Upvotes: 9

Yoichi
Yoichi

Reputation: 12261

nohup node server.js > /dev/null 2>&1 &

  1. nohup means: Do not terminate this process even when the stty is cut off.
  2. > /dev/null means: stdout goes to /dev/null (which is a dummy device that does not record any output).
  3. 2>&1 means: stderr also goes to the stdout (which is already redirected to /dev/null). You may replace &1 with a file path to keep a log of errors, e.g.: 2>/tmp/myLog
  4. & at the end means: run this command as a background task.

Upvotes: 1161

thiagowfx
thiagowfx

Reputation: 5760

I have this function in my shell rc file, based on @Yoichi's answer:

nohup-template () {
    [[ "$1" = "" ]] && echo "Example usage:\nnohup-template urxvtd" && return 0
    nohup "$1" > /dev/null 2>&1 &
}

You can use it this way:

nohup-template "command you would execute here"

Upvotes: 7

Arnab Nandy
Arnab Nandy

Reputation: 6712

$ disown node server.js &

It will remove command from active task list and send the command to background

Upvotes: 7

stop zionism
stop zionism

Reputation: 398

another solution disown the job

$ nohup node server.js &
[1] 1711
$ disown -h %1

Upvotes: 27

Daniel Gallagher
Daniel Gallagher

Reputation: 7125

nohup will allow the program to continue even after the terminal dies. I have actually had situations where nohup prevents the SSH session from terminating correctly, so you should redirect input as well:

$ nohup node server.js </dev/null &

Depending on how nohup is configured, you may also need to redirect standard output and standard error to files.

Upvotes: 16

S.Lott
S.Lott

Reputation: 391972

Have you read about the nohup command?

Upvotes: 6

Related Questions