Executing an exe from a java program

I want to execute an exe file (say, a.out) in hp-ux 10.20 from the java program.

1) The java code
Runtime.getRuntime().exec(". ./a.out");
is NOT WORKING

2) The java code
Runtime.getRuntime().exec("a.out");
is NOT WORKING

3) I wrote a script (say, test)
#!/bin/sh
a.out
Then i called this script from the java program
Runtime.getRuntime().exec("test");
This is also NOT WORKING
4) I wrote a script (say, test)
a.out
Then i called this script from the java program
Runtime.getRuntime().exec(new String[] {"/bin/sh", "test"});
This code is WORKING
Could someone please explain me why the codes (1, 2 and 3) are not working and why the code 4 is working...Thanks a lot...

My guess is that it is one of two problems:

you may have assumed the wrong "current directory". Notice that the only one which works is the one with a full path to "/bin/sh". Can you try one of the other examples but using the full path to the executable, ie "/home/someone/tests/a.out" or whatever ?

you may have forgotten to make your examples executable. Remember that for any *nix system to execute a binary or script file it needs to have the "x" bit set for an appropriate user. Try ls -l a.out and look for something like rwxr-xr-x . If there are no 'x' characters, try chmod 755 a.out then try to execute it again.

Please let us know how you get on.

Hi Frank Carver:
Thank you very much for your reply.
I tried with full path...it is working fine. Once again, thanks.
But i have a doubt now
1) Runtime.exec("java MyExample") works fine...where MyExample is a .class file in the directory /home/someone/test. It is WORKING FINE WITHOUT GIVING FULL PATH
2) Runtime.exec("a.out") is not working...where a.out is an exe file in the directory /home/someone/test. It is NOT WORKING WITHOUT GIVING FULL PATH
3) Runtime.exec("/home/someone/test/a.out") is working...where a.out is an exe file in the directory /home/someone/test. It is WORKING BY GIVING FULL PATH
Could you please explain me what is happening in all the three cases.
Also please explain the code 3 and 4 what i had written yesterday...
Waiting for your reply to understand the concepts behind it.
Thanks a lot.
Uma

This situation arises because your current directory is not in your PATH, whereas the directory containing the "java" executable is in the PATH.
type echo $PATH to see what is in your path.
On most modern *nix systems, the current directory (.) is not in the PATH, as it is seen to present too much of a security risk. You might be able to get this working without a full path by using . as the path for the command ie.:
Runtime.getRuntime().exec("./a.out");
This is almost like your original example 1, but doesn't have the leading "." and space, which only work in the context of a shell.

Hi Frank Carver:
Please do confirm the following:
1) I had written "The code Runtime.getRuntime().exec("a.out") is not working...where a.out is an exe file in the directory /home/someone/test. It is NOT WORKING WITHOUT GIVING FULL PATH"
The reason is: Runtime.getRuntime().exec tries to search the a.out in the home directory...i tested by copying the a.out to the home directory and execute the above code. It works fine.

2) I had written
"I wrote a script (say, test)
#!/bin/sh
a.out
Then i called this script from the java program
Runtime.getRuntime().exec("test"); This is also NOT WORKING"
The reason is: Runtime.getRuntime().exec does not spawn a shell but we need a shell to run the script.
The test script above (which contains the command #!/bin/sh) does not spawn a shell...so, it is not working.
3) I had written
"I wrote a script (say, test)
a.out
Then i called this script from the java program
Runtime.getRuntime().exec(new String[] {"/bin/sh", "test"}); This code is WORKING"
The reason is: This works bcoz the first parameter to exec (i.e., /bin/sh) spawns a shell.
Frank Carver: please confirm whether my understanding is correct or not....Also add your views/points...
4) I had written "Runtime.exec("/home/someone/test/a.out") is working...where a.out is an exe file in the directory /home/someone/test. It is WORKING BY GIVING FULL PATH"
Here we are hard coding the directory name, which will not be good in a project. So, could you please tell me the way to specify the directory name.
Thanks a lot.
Uma

Sorry..i did not see ur previous reply when i had posted my earlier one...i typed the message and then it was time to go for the meeting...after i came back...i just clicked "Add reply"...

No problem. I'm sure we all do that from time to time. Please let me know if my other suggestion does work, though.

Hi Frank Carver:
Thanks for your reply.
Runtime.getRuntime().exec("./a.out"); is not working
but it is working if i include . (i.e, current directory) in the PATH.
Also i am able to run the exe thru a script.
Thanks a lot for your ideas.
Uma