I run a local server using Thin server. When it starts successively, it returns a message like this:
>> Thin web server (v1.3.1 codename Triple Espresso)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:3000, CTRL+C to stop
I want to run a web browser right after the server starts successfully. I feel that it should be possible to catch the message from thin using some kind of pipe, and starting a web browser as soon as that message is received, but am not sure about the details. How can I do that? The code for starting Thin is something like:
Rack::Handler::Thin.run(...)
so I think that piece of code should be embedded somehow in a pipe.
In your shell, type the following:
alias thin='/usr/bin/thin && firefox http://localhost:3000/ &'
(Or, whatever the path to the thin server is.)
Now, from that shell, type thin and your server will start and once it succeeds, firefox will start.
If you like this, add this to your shell's startup files, such as ~/.bashrc. (The startup files can be complicated; see the bash(1) manpage for full details.)
Related
I've written a TCP Server in ruby running on port 2000 with event machine.
Right now, what I do is ssh to my server and run the command ruby lib/tcp_server.rb to turn on the server, but it shuts down when I log out.
I've tried nohup and using & but nothing seems to stick for the server for a long time.
So my question is, how do I deploy this server on port 2000 and keep it running, like how we deploy Rails to nginx.
It's not a webserver, but an a tcp server for a connected device, if that helps.
Thanks!
Solution 1: tmux or screen
This is the simplest way to approach, you will have to create a tmux or screen session, then start your server in that session.
Solution 2: nohup
nohup ruby lib/tcp_server.rb > stdout.log 2> stderr.log &
You've tried nohup and using &, I suppose you've already known how to do.
Solution 3: daemonize
You can detach from the shell and daemonize the process by forking
it twice, setting the session ID and changing the current working directory.
def daemonize
exit if fork
Process.setsid
exit if fork
Dir.chdir '/'
end
With this approach, you will have to redirect stdout and stderr to keep logs.
Another way to daemonize is to use gems like daemons.
update:
To restart the process automatically after being killed, you need a process manager like god or pm2.
To start the process automatically after booting, you need to compose an init scripts but how it looks like depends on your service management system and operating system. One of the most well-known is System V. If you are using Ubuntu, you might want to take a look at Upstart or systemd.
I noticed that if I set another port number instead of the default one in derby (1527) in the derby.properties with for instance:
derby.drda.portNumber=1528
It will then correctly start up the server on that new port but unfortunately when calling stop script it will still attempt to kill something on the default port and leaving the derby alive. Is that a bug or is there something else that needs to be addressed in the properties file to make it work?
You are probably looking for the -p portnumber argument to stopNetworkServer: http://db.apache.org/derby/docs/10.13/adminguide/tadminconfigshuttingdownthenetworkserver.html
I am trying to do some work on a remote machine and disconnect without terminating the work. I have tried both nohup and screen, unfortunately it is not working out. After I type exit to logout my work also terminates immediately.
I am trying to run 108 simulations on a remote machine. For that purpose I have written a script named batch.sh which runs one simulation after the other until all 108 are done. The program that actually runs a simulation launches 5 programs in 5 different terminals (using xterm -e). I run batch.sh using:
nohup bash batch.sh &
As long as I am connected everything works just fine. If I disconnect and then reconnect to check whether everything is working as it should...no joy :(
Are there any caveats I am overlooking? Possibly because my program launches other programs in external terminals?
UPDATE
If I use the suggestions of adding -oForwardX11=no to ssh and unset DISPLAY before launching my script I get these errors:
nohup: ignoring input and appending output to nohup.out
In nohup.out I have these messages:
xterm Xt error: Can't open display:
xterm: DISPLAY is not set
Apparently your script/program is trying to launch xterm on its own. These days many systems enable X11 forwarding for their SSH client by default - as a result the DISPLAY variable is set in your shell session but becomes invalid once you disconnect. Therefore, as long as you are connected to the remote system, the xterm processes can access the X server on your local machine through the SSH connection, but die once that connection is severed.
I have occasionally encountered the same issue with Java programs that use e.g. the Java AWT subsystem to generate image files, even when there is no actual graphical window. You should first see if your program will somehow adapt if there is no X server available. One option is to disable X11 forwarding with the -oForwardX11=no option to ssh:
$ ssh -oForwardX11=no user#server.host.name
You could also try unsetting the DISPLAY environment variable before starting your script and see what happens.
However, if your program is launching xterm windows indiscriminately then you'd have to make it e.g. use an output file on the server instead - by modifying it, if necessary. As an added advantage, you would get rid off the network load and timing overhead involved with forwarded X connections.
If you cannot change the way your program works and you do not actually care about the output in those xterm windows, then you could try launching a virtual framebuffer X server on the remote system and have your script use that for xterm.
I need to open an ssh connection on login and keep it open, but to not acutally do anything with it. It would be best if all of it would run in the background.
I created an automator application and made it run a shell script on the bash. The script looks as follows:
sshpass -p 123456 ssh 123456#123.123.123.123
If i try to run the application i keep getting an error message, however if i execute the exact same script in an terminal it works just fine.
Is there any way i can open that connection with an automator application and keep in the background?
You can send a KeepAlive packet to stop the pipe from closing.
In your ~/.ssh/config, and the following:
Host *
ServerAliveInterval 300
ServerAliveCountMax 2
What this says is that that every 300 seconds, send a null (keep-alive) packet and give up after 2 tries.
Source: http://patrickmylund.com/blog/how-to-keep-alive-ssh-sessions/
Do you really need to involve Automator at all?
Just save the script (say, foo.sh) in a folder with the same name as the script (i.e. foo.sh as well).
Put this folder in /System/Library/StartupItems/ and it will run when you start up your machine.
One of our application servers (Glassfish v3.0.1) keeps crushing down with no reason. Sometimes, I am away from Internet so I cannot run it back again. Therefore, I wrote a simple bash script to wait for 10 minutes and then run asadmin. It is like:
#!/bin/bash
while true;
do sleep 600;
sudo /home/ismetb/glassfishv3.0.1/glassfish/bin/asadmin start-domain;
done
This seems to work fine however I have a couple of problems:
If I terminate the bash script (by pressing ctrl+z buttons), the Java process (Glassfish) dies and start-domain and stop-domain commands do not work at all. That means, I can neither stop Glassfish nor can I access it. I do not know if anybody else experienced this problem before or not. If the process dies, only thing I can do is to look for the ID of Java process and kill it from terminal. This not desirable at all. Any ideas why Java process dies when I quit script?
What I want to add to my script is something like to check the port Glassfish is using. If port is occupied maybe I can assume that Glassfish is not down! (However, the port (8080 default) might still be used by Glassfish although Glassfish is dead, I am not sure of it). If not, then with the help of a simple code, I can get the id of the Java process and kill them all. Then start-domain command will successfully work. Any ideas or any directions on how I can do this?
You can use a cron job instead. To install a cron job for root, enter
sudo crontab -e
and add this line
*/10 * * * * /home/ismetb/glassfishv3.0.1/glassfish/bin/asadmin start-domain
This will run asadmin every ten minutes.
If you're not comfortable with the command line, you might also try gnome-schedule, but I have no experience with that.
For your second problem, you can use curl or wget to access glassfish. You can try to get some URL, or even access the administration interface, and if you don't get a response, assume glassfish is down.