FOR /F "skip=2 tokens=2*" %%A IN ('REG QUERY "HKLM\Software\JavaSoft\Java Runtime Environment" /v CurrentVersion') DO set CurVer=%%B
FOR /F "skip=2 tokens=2*" %%A IN ('REG QUERY "HKLM\Software\JavaSoft\Java Runtime Environment\%CurVer%" /v JavaHome') DO set JAVA_HOME=%%B
echo JAVA_HOME: %JAVA_HOME%
SET JAVA=%JAVA_HOME%\bin\javaw.exe
echo JAVA: %JAVA%

            string bat = System.IO.Path.Combine(Directory.GetCurrentDirectory(), "start.bat");

            string Xmx = this.textBox1.Text;
            string Xmn = this.textBox2.Text;
            string NAME = this.textBox3.Text;

            Process proc = null;
            proc = new Process();

            proc.StartInfo.FileName = bat;
            proc.StartInfo.Arguments = String.Format("{0} {1} {2}", Xmx, Xmn, NAME);
            proc.StartInfo.UseShellExecute = false;
            proc.StartInfo.CreateNoWindow = true;
            proc.StartInfo.WorkingDirectory = Path.GetDirectoryName(proc.StartInfo.FileName);
            proc.StartInfo.RedirectStandardOutput = true;
            proc.StartInfo.RedirectStandardError = true;
            proc.Start();

            string procOutput = proc.StandardOutput.ReadToEnd();
            string procError = proc.StandardError.ReadToEnd();

            TextWriter outputlog = new StreamWriter(System.IO.Path.Combine(Directory.GetCurrentDirectory(), "instancias\\pruebas\\.minecraft\\log.txt"));
            outputlog.Write(procOutput);
            outputlog.Close();

            TextWriter outputerror = new StreamWriter(System.IO.Path.Combine(Directory.GetCurrentDirectory(), "instancias\\pruebas\\.minecraft\\error.txt"));
            outputerror.Write(procError);
            outputerror.Close();

SET BASE=.\ 
FOR /F "skip=2 tokens=2*" %A IN ('REG QUERY "HKLM\Software\JavaSoft\Java Runtime Environment" /v CurrentVersion') DO set CurVer=%B 
FOR /F "skip=2 tokens=2*" %A IN ('REG QUERY "HKLM\Software\JavaSoft\Java Runtime Environment\" /v JavaHome') DO set JAVA_HOME=%B 
echo JAVA_HOME:  
JAVA_HOME: 
SET JAVA=\bin\javaw.exe 
JAVA: \bin\javaw.exe