Write all System.out into a file

Question

I have a large program in which I have used System.out for debugging. But I'd like to be able to log all System.out simultaneously to a file so even if my program isn't run in the console all the System.out will be written to a file and I will be able to see it in any moment the program is running or later.

Btw, it's not wise to crawl all the program and use a logger instead of System.out statements!

I tried java -jar myjar.jar > sysout.txt but it doesn't log the exceptions logged by java logger utility.

possible duplicate of [How to write console output to a txt file](http://stackoverflow.com/questions/1994255/how-to-write-console-output-to-a-txt-file) — But I'm Not A Wrapper Class, Jan 02 '14 at 18:22
There is no difference between > and 2>&1> what does it mean? It doesn't log the exceptions bis! @C.B. — Johnny, Jan 02 '14 at 18:22

Meno Hochschild · Accepted Answer · 2014-01-02T18:43:28.003

5

What about System.setOut(PrintStream) ? You could insert this call in the initialization part of your program (start-up).

Was previously a commment:

And of course you can do the same with System.err - namely System.setErr(PrintStream), but better to a different file stream.

In detail assuming an autoflushing appending and buffered file stream:

    String file = ...;
    PrintStream ps = 
      new PrintStream(true, new BufferedOutputStream(new FileOutputStream(file, true)));
    System.setOut(ps);

edited Jan 02 '14 at 18:43

answered Jan 02 '14 at 18:19

Meno Hochschild

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And of course you can do the same with `System.err` - namely `System.setErr(PrintStream)`, but better to a different file stream. – Meno Hochschild Jan 02 '14 at 18:24
I think it is better if you edited your answer to include the details of your comment above. That would make it a more complete answer. :) – Buddhima Gamlath Jan 02 '14 at 18:36

score 4 · Answer 2 · answered Jan 02 '14 at 18:21

4

The normal redirection command_name args > output only redirect Standard Output. It does not redirect Standard Error stream, where usually the errors are logged in. To output both streams to the same file use,

command args &> filename

eg. java -jar myjar.jar &> sysout.txt

To redirect to different files, use

command args 1> output_file 2> error_file

eg. java -jar myjar.jar 1> sysout.txt 2> errout.txt

See more options at http://www.tldp.org/LDP/abs/html/io-redirection.html

answered Jan 02 '14 at 18:21

Buddhima Gamlath

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excellent! That's very nice however I find the Meno Hochschild's answer more flexible because it is Java-ish and I will be able to make daily dev logs! – Johnny Jan 02 '14 at 18:31
@Johnny: Yup, that way you do not have to rely on the execution commands. :) – Buddhima Gamlath Jan 02 '14 at 18:37

Write all System.out into a file

2 Answers2