I've been reading about it, and I've tried one of the solutions that I've found in the internet, but it still doesn't work yet.
I want to execute
java -jar /home/ubuntu/MyJavaJar.jar
once a year starting in October 12 at 12:34
I'm sorry if this is a really basic question, but I can't find a solution yet. I don't have a graphic interface, so the solution should be using the console.
Also, if there was another way to do this (without using linux cron) e.g. connect using putty and launch the java jar and then disconnect from putty (in my windows-based computer, that needs to be turned off regularly) (but without cancelling the jar execution on the Linux computer, that doesn't need to be turned off) would be an even better answer.
Thanks in advance.
You can use nohup:
nohup java -jar /home/ubuntu/MyJavaJar.jar &
Related
I have a script to start and stop my services. My server is based on Linux. How do I automate the process such that when OS is shutdown the stop script runs and when it is starting up, the start script runs?
You should install init script for your program. The standard way is to follow Linux Standards Base section 20 subsections 2-8
The idea is to create a script that will start your application when called with argument start, stop it when called with argument stop, restart it when called with argument restart and make it reload configuration when called with argument reload. This script should be installed in /etc/init.d and linked in various /etc/rd.* directories. The standard describes a comment to put at the beginning of the script and a uitlity to handle the installation.
Please, refer to the documentation; it is to complicated to explain everything in sufficient detail here.
Now that way should be supported by all Linux distribution. But Linux community is currently searching for better init system and there are two new, improved, systems being used:
systemd is what most of the world seems to be going to
upstart is a solution Ubuntu created and sticks to so far
They provide some better options like ability to restart your application when it fails, but your script will then be specific to the chosen system.
I want to create an application that runs in the background in Linux (daemon) that will basically at set times (5 times) play a music file or any sound given every single day. I want this daemon to start when the computer is started in terminal mode (non-GUI). I want to know if this is possible and if so, What considerations, tools, and programming language would be the most efficient in doing so? This will be a dedicated computer that will only be executing this task, so if any recommendations on how I can maximize efficiency while disabling other features that are not required for this task will be appreciated. Also, could you please explain how processes and tasks work in terminal (non-GUI)? I always thought terminal was something like CMD in Windows and can only run tasks one at a time.
EDIT: I need the sound to run at variable times, I'll be fetching these times from a website. Any suggestions regarding how to achieve this?
Thanks for the help and sorry for any shortcoming in the questions or my research.
Look at using cron to run your tasks. cron is a very flexible scheduling utility built in to most Linux distributions.
Basically, with cron you specify a task to run (your main program, or maybe just a sound-playing program), all of its arguments, and when it runs. cron takes care of running it, and will even send you "mail" if the job produces any output (such as errors).
You can make processes fork into a subprocess of your terminal, i.e. you are able to run more than one task at a time by putting a & after your terminal command:
> cmd&
> [you can type other commands here but the "cmd" program is still running]
However, for services you generally don't have to worry about starting it as a subprocess because the system already knows to do this. Here's a good question from Super User that has an example of a working service. Simply place your service as a shell script in the /etc/init.d and it will be automatically started as a service.
I am experiencing a very strange behavior with oracle, maybe somebody can help me, let me summarize it real quick:
My OS of choice is debian linux, I am using Oracle XE 11.0.2.0. On linux startup, I run a script file which is located under /etc/init.d/. I added the following line to make oracle start on system start:
/etc/init.d/oracle-xe start
Right after this line , I run my application from the script, my application heavily relies on the oracle db, therefore once oracle starts, I am positive that my application will run ok. Unfortunately my assumption seems wrong.Here's why: I set up similar set up in 3 machines, in 2 of them I see weird behavior, after system start oracle db is not responding to connection requests, Even though oracle-xe start command completed executing.
My observation is the following, if I run my application right after oracle-xe start is executed, I receive ora-12505 errors at least for a minute: "TNS listener does not currently know of SID" . After a minute everything stabilizes, and my application starts working ok. 1 minute without a db on system startup is not acceptable for me performance-wise, therefore I am trying to solve this problem.
Surprisingly it does not happen in one of the other linux boxes I have here, I am not quite sure what is different on that box. I compared ora files, but couldn't find any difference, it seems like a wild goose chase...
I would be so grateful if anybody has experienced and solved ths problem before and shares that valuable solution with me.
I think I found the problem, looks like I am starting oracle-xe instance before I assign network interfaces an IP address, in that case it takes some time for oracle to receive connections, that requires me to set static ip on the linux boxes, which is something I don't want. Is there a solution so that I can still assign IP addresses later on?
I am using derby on a remote Ubuntu 12.04 server. The standard derby commands are all working correctly and I am able to open my databases and access them via ij. I need to be able to start and stop the server from the terminal while logging in and out between commands. The problem is that I can not find a way to run the server as a background process. The closest I have come is: nohup java -jar $DERBY_HOME/lib/derbyrun.jar server start & > ~/dblog.txt which works except that it requires I hit [enter] before returning to the command line. I am aware of the daemon package but I am uncertain of whether it will allow me to then stop the server. What would be helpful is a explanation of how tomcat manages it since that is my app server.
Derby is just a Java application. Any technique you wish to use to run Java applications in the background (/etc/init.d, job control in your shell, etc.) will work fine for Derby.
You can use commands like "kill" or "killall" to kill your background process. Use "jobs" command to see list of running process you've sent to background. Also you can put them back in foreground by doing - "fg %n" (where n is the job number) and kill it using CTRL-C.
I wonder if there is a way to detect if a Tomcat Server has been crashed on a LInux machine? How can i
recover it (- start it) automatically?
I can do it through a cron job. But that is not what i Want!
I want to detect immediately the time that Tomcat crashed!
Is there a way?
Any help?
Antonis
Take a look at mysqld_safe. It is mysql's launch script that monitors mysql and can recover from some errors and relaunch mysql again. You might get some hints on how to do the same thing for tomcat.
A link on how the script work is here.