System.getenv("computername") truncating return value

Question

What is the difference between System.getenv("computername") and System.getenv("hostname") in Java?

Is there any character limit on the computer name when retrieving it using the getenv() method?

I have a lengthy hostname and System.getenv("computername") seems to be truncating it to 15 characters. OS used is Windows.

Is this specific to Java? What happens when you view the environment variable in `cmd`? — Mark Peters, Nov 14 '12 at 17:32
this is specific to java when the value is retrieved using java code. it is fine from the cmd prompt. — user811433, Nov 14 '12 at 17:33
Are you suggesting that `getenv("hostname")` doesn't truncate the return value? Do you get back more than 15 characters with that environment variable? — Duncan Jones, Nov 14 '12 at 17:54
No. Wrote a few lines of code and found that computername is for Windows env and hostname is for unix env. Still unsure about the 15 character limit. — user811433, Nov 14 '12 at 18:00

score 1 · Answer 1 · answered Mar 04 '14 at 15:46

1

The truncation in Windows is due to NetBIOS having a computer name length limit of 15 characters.

answered Mar 04 '14 at 15:46

G. Stevens

score 1 · Answer 2 · answered Jun 03 '14 at 08:01

1

This is working:

try {
return InetAddress.getLocalHost().getHostName();
} catch (UnknownHostException e) {
return "Error: UnknownHostException";
}

Hope I help you.

Sam'

answered Jun 03 '14 at 08:01

SamaelStern

score 0 · Answer 3 · answered Nov 14 '12 at 18:00

0

I wrote a simple test application:

public class Test {
  public static void main(String[] args) {
    System.out.println(System.getenv("computername"));
  }
}

and then executed:

set COMPUTERNAME=abcdefghijklmnopqrstuvwxyz
java Test

which printed:

abcdefghijklmnopqrstuvwxyz

Works fine in both Java 5 and 7 on Windows. No sign of truncation.

answered Nov 14 '12 at 18:00

Duncan Jones

Based on your code here, I tried setting the computername and executing the program. It works fine. I get the expected computername. But when I try to get the computername of my machine on a network I get the truncated value. – user811433 Nov 14 '12 at 18:16
And `echo %COMPUTERNAME%` on the command line shows the untruncated value? – Duncan Jones Nov 14 '12 at 18:17
No, it shows the proper value. Executing the program from cmd prompt after doing a SET also shows proper value. Only when the actual computername is long (not via SET), I see the truncated value when I execute the program from eclipse. – user811433 Nov 14 '12 at 18:22

3 Answers3