Background Running Process logging

Question

Am having a java program which listens to ApacheMQ and runs in background and am using Linux Server. Here I have used System.out.println() for my logging andI have to transfer those contents to a file.

Is it possible, am completely novice to this and Whether I have to use Log4J or nohup to write this sysout() value to a file.

Thanks in advance.

Answer 1

As you observe, using nohup you get out redirected to a file. More generally, a linux process can have its output redirected to a file

 myApp > someFile.log

or maybe better appended to a file

 myApp >> someFile.log

so that when you restart you don't lose previous output.

Alternatively, as you indicate, you can put the app in charge of choosing where to write, and then using a library such as Log4j instead of System.out is very helpful.

I would use both approches: I recommend using some such logging library in any serious application, and I would start my application from a script that ensures that all output is captured in log files, this ensures that should you use some library code that writes to a stdout or stderr that the output is kept. I like to create output files whose names include date and time that the app was started, this makes it easier to find particular output.

Answer 2

You can use

PrintWriter out = new PrintWriter("my-output.txt");

// write text.
out.println("hello world");

// when finished.
out.close();

Just replace System.out with out

I am surprised you can use JMS but don't know how to work out how to write to a file.