Invoke a Java file using System() in c

Asked Apr 11 '13 at 21:35

Active Apr 11 '13 at 23:03

Viewed 396 times

I am trying to run a java file that is sitting on my web server from c code. When I load the webpage, a perl script calls a c file which then calls the java file.

I have the call set up like in my c file:

System(java -cp <path> MyClass);

But this System() call returns 256 - (file not found I think).

I have also tried:

System(cd /<path> && java MyClass);

And get the same results.

If I run the exact same command from the terminal via ssh, it works fine, it is just when I try running the code from my browser that it gives this error.

Any ideas if my syntax is incorrect? Or am I doing something else wrong? Does it have something to do with the perl > c > java chain I am forced to use?

EDIT It appears that the c runtime was not looking at $PATH. I added the absolute path to java.exe, and it worked! Wooo

tldr

solution:

System("/opt/jdk1.6.0_43/bin/java -cp <path> MyClass");

edited Apr 11 '13 at 23:03

asked Apr 11 '13 at 21:35

Toadums

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Can't you just run `java -cp MyClass` directly from the Perl script? – Kninnug Apr 11 '13 at 21:37
unfortunately not, because a bunch of data is generated from existing c code. So I need to do it this way unfortunately.. – Toadums Apr 11 '13 at 21:38
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According to [this](http://stackoverflow.com/questions/3736320/executing-shell-script-with-system-returns-256-what-does-that-mean), your error is actually being multiplied by 256, and your return is actually `1`. – syb0rg Apr 11 '13 at 21:41
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Can you provide the exact code in your C file? (Not necessarily the entire C file, but the relevant parts as they appear in the C file) Because `System(java -cp MyClass);` shouldn't even compile. – Kninnug Apr 11 '13 at 21:43
The code is just system(java -cp /theory/www/bin/tree MyClass); – Toadums Apr 11 '13 at 21:46
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You mean `system(java -cp /theory/www/bin/tree MyClass);` right? – squiguy Apr 11 '13 at 21:46
yes, system not System – Toadums Apr 11 '13 at 21:47
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The normal way to solve this problem is to `fork()` and then `exec()` from the newly spawned process. – syb0rg Apr 11 '13 at 21:49
yeah, I was thinking of trying to fork and exec. I was just hoping that this would work :) I will try that, thanks! – Toadums Apr 11 '13 at 21:50
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also, `system` is expecting a `string` right? Eg. `system("ls -l")`; – chrsblck Apr 11 '13 at 21:51
Yes, sorry it is a string – Toadums Apr 11 '13 at 21:52
@Toadums Is it Linux or Windows system? – Bechir Apr 11 '13 at 22:03
The server is running redhad – Toadums Apr 11 '13 at 22:05
Did you check that the script is running with the appropriate rights? The `PATH` includes the binary path of `java` ... It may have a different configuration from yours. – Bechir Apr 11 '13 at 22:13
You should try `system("pwd"); `system("echo $PATH");` to check that normal commands work, and find out where you are/what the `PATH` is. – not all wrong Apr 11 '13 at 22:27
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You should post your solution as an answer and choose it instead of editing your question – Felype May 21 '13 at 13:44

Invoke a Java file using System() in c

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