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I have tried coding a servlet which creates a file based on the inputs given to it.The file gets created along with appropriate text but I am unable to give the file 777 permissions and I am also unable to run ProcessBuilder later. I thought it is inter related because the command fired in ProcessBuilder would require the file to have appropriate permissions but when I try giving it permissions using chmod it doesn't work either. 

import java.io.*;
import java.util.Enumeration;
import javax.servlet.*;
import javax.servlet.http.*;
import java.lang.*;
import java.io.*;
import java.util.*;
public class Serv extends HttpServlet
{ 
    private static final long serialVersionUID = 1L;
    public void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
    {
    String jobId=req.getParameter("jobId");
    String jobStatus=req.getParameter("jobStatus");
    String displayName=req.getParameter("displayName");
    String name=req.getParameter("name");
    String description=req.getParameter("description");
    String frequency=req.getParameter("frequency");
    String lastModifiedAt=req.getParameter("lastModifiedAt");
    String createdAt=req.getParameter("createdAt"); 
    String createdBy=req.getParameter("createdBy");     
    String opPath=req.getParameter("opPath");       
    String env=req.getParameter("env");     
    res.setContentType("text/html");
    PrintWriter pw=res.getWriter();
    pw.println("JobId: \n"+jobId);
    pw.println("JobStatus: \n"+jobStatus);
    String path = getServletContext().getRealPath("/");
    File logfile=new File("/var/lib/tomcat7/webapps/ROOT/log.txt");
    logfile.setReadable(true);
    logfile.setWritable(true);
    logfile.setExecutable(true);    
    PrintWriter writer = new PrintWriter(path+"log.txt", "UTF-8");
    writer.println("Job ID : "+jobId);
    writer.println("Job Status : "+jobStatus);
    writer.println("Rule Name : "+name);
    writer.println("Rule Display Name : "+displayName);
    writer.println("Rule Description : "+description);
    writer.println("Rule env : "+env);
    writer.println("Rule frequency : "+frequency);
    writer.println("Rule last modified at : "+lastModifiedAt);
    writer.println("Rule created at : "+createdAt);
    writer.println("Rule created by : "+createdBy);
    writer.println("Notification Path : "+opPath);
    writer.close();
    pw.close();
    try
        {
        // ProcessBuilder pb1=new ProcessBuilder("sudo","/bin/chmod","777","/var/lib/tomcat7/webapps/ROOT/log.txt");
        // pb1.redirectErrorStream(true);
        // Process p1=pb1.start();
        // InputStreamReader isr1 = new  InputStreamReader(p1.getInputStream());
        // BufferedReader br1 = new BufferedReader(isr1);
        // String lineRead1;
        // while ((lineRead1 = br1.readLine()) != null) 
        //     {
        //  System.out.println(lineRead1);
        //     }
        // p1.waitFor();
        ProcessBuilder pb2=new ProcessBuilder("/usr/local/hadoop/bin/hadoop", "fs", "-copyFromLocal", "/var/lib/tomcat7/webapps/ROOT/log.txt",opPath);
        pb2.redirectErrorStream(true);
    //  pb2.directory(new File("/var/lib/tomcat7/webapps/ROOT/"));
        Process p2=pb2.start();
        InputStreamReader isr2 = new  InputStreamReader(p2.getInputStream());
        BufferedReader br2 = new BufferedReader(isr2);
        String lineRead2;
        while ((lineRead2 = br2.readLine()) != null) 
            {
            System.out.println(lineRead2);
            }
        p2.waitFor();
        }
    catch(Exception e){}

    }
    public void doPost(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
    {
    String jobId=req.getParameter("jobId");
    String jobStatus=req.getParameter("jobStatus");
    String displayName=req.getParameter("displayName");
    String name=req.getParameter("name");
    String description=req.getParameter("description");
    String frequency=req.getParameter("frequency");
    String lastModifiedAt=req.getParameter("lastModifiedAt");
    String createdAt=req.getParameter("createdAt"); 
    String createdBy=req.getParameter("createdBy");     
    String env=req.getParameter("env");     
    String opPath=req.getParameter("opPath");       
    res.setContentType("text/html");
    PrintWriter pw=res.getWriter();
    pw.println("JobId: \n"+jobId);
    pw.println("JobStatus: \n"+jobStatus);
    String path = getServletContext().getRealPath("/");
    File logfile=new File("/var/lib/tomcat7/webapps/ROOT/log.txt");
    logfile.setReadable(true);
    logfile.setWritable(true);
    logfile.setExecutable(true);    
    PrintWriter writer = new PrintWriter(path+"log.txt", "UTF-8");
    writer.println("Job ID : "+jobId);
    writer.println("Job Status : "+jobStatus);
    writer.println("Rule Name : "+name);
    writer.println("Rule Display Name : "+displayName);
    writer.println("Rule Description : "+description);
    writer.println("Rule env : "+env);
    writer.println("Rule frequency : "+frequency);
    writer.println("Rule last modified at : "+lastModifiedAt);
    writer.println("Rule created at : "+createdAt);
    writer.println("Rule created by : "+createdBy);
    writer.println("Notification Path : "+opPath);
    writer.close();
        pw.close();
        try
        {
        // ProcessBuilder pb1=new ProcessBuilder("sudo", "/bin/chmod","777", "-R", "/var/lib/tomcat7/webapps/ROOT/log.txt");
        // pb1.redirectErrorStream(true);
        // Process p1=pb1.start();
        // InputStreamReader isr1 = new  InputStreamReader(p1.getInputStream());
        // BufferedReader br1 = new BufferedReader(isr1);
        // String lineRead1;
        // while ((lineRead1 = br1.readLine()) != null) 
        //     {
        //  System.out.println(lineRead1);
        //     }
        // p1.waitFor();
        ProcessBuilder pb2=new ProcessBuilder("/usr/local/hadoop/bin/hadoop", "fs", "-copyFromLocal", "/var/lib/tomcat7/webapps/ROOT/log.txt",opPath);
        pb2.redirectErrorStream(true);
    //  pb2.directory(new File("/var/lib/tomcat7/webapps/ROOT/"));
        Process p2=pb2.start();
        InputStreamReader isr2 = new  InputStreamReader(p2.getInputStream());
        BufferedReader br2 = new BufferedReader(isr2);
        String lineRead2;
        while ((lineRead2 = br2.readLine()) != null) 
            {
            System.out.println(lineRead2);
            }
        p2.waitFor();
        }
    catch(Exception e){}
    }
}

It would be really great if anyone could help.

For Convenience : File Permissions

File logfile=new File("/var/lib/tomcat7/webapps/ROOT/log.txt");
logfile.setReadable(true);
logfile.setWritable(true);
logfile.setExecutable(true);

ProcessBuilder :

ProcessBuilder pb2=new ProcessBuilder("/usr/local/hadoop/bin/hadoop", "fs", "-copyFromLocal", "/var/lib/tomcat7/webapps/ROOT/log.txt",opPath);
        pb2.redirectErrorStream(true);
    //  pb2.directory(new File("/var/lib/tomcat7/webapps/ROOT/"));
        Process p2=pb2.start();
        InputStreamReader isr2 = new  InputStreamReader(p2.getInputStream());
        BufferedReader br2 = new BufferedReader(isr2);
        String lineRead2;
        while ((lineRead2 = br2.readLine()) != null) 
            {
            System.out.println(lineRead2);
            }
        p2.waitFor();
Akshay Hazari
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  • possibly duplicate - http://stackoverflow.com/questions/6233541/java-set-file-permissions-to-777-while-creating-a-file-object – sprabhakaran Jul 22 '14 at 09:33
  • @hellospk But it is not working with Servlets. Is there any particular thing needed to do in case of servlets like using String path = getServletContext().getRealPath("/"); and adding that before log.txt as path,just because I needed to that in order to write to log.txt file . But that didn't work either when used to set permissions. – Akshay Hazari Jul 22 '14 at 09:35
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    jdk-7 may be solve your problem http://www.journaldev.com/855/how-to-set-file-permissions-in-java-easily-using-java-7-posixfilepermission – sprabhakaran Jul 22 '14 at 09:41
  • Tried that and the permissions part worked but it still doesn't execute the ProcessBuilder part of it. – Akshay Hazari Jul 22 '14 at 09:48

1 Answers1

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Sorry About unintentionally misguiding earlier. The problem actually lied in hadoop's storage system (hdfs) and I thought it was definitely a problem with tomcat or Servlets. I thought of deleting the question as soon as I found this out but then I thought that It would benefit someone else , as I could not find anything on it for 2 days.

I found this to help me finally Permission denied at hdfs.

-copyFromLocal or -put needs to have some permissions I suppose and just adding the following in hdfs-site.xml and then running it worked.

 <property>
    <name>dfs.permissions</name>
    <value>false</value>
  </property>

Also I tried the same in php and it is much less of a hassle than jsp or servlet.

This is what I did finally in php

<?php
  if( $_GET["jobId"] || $_GET["jobStatus"] )
  {
     echo "Job Id ". $_GET['jobId']. "<br />";
     echo "Job Status ". $_GET['jobStatus']. "";
  }
  $jobId=$_GET["jobId"];
  $jobStatus=$_GET["jobStatus"];
  $displayName=$_GET["displayName"];
  $name=$_GET["name"];
  $description=$_GET["description"];
  $frequency=$_GET["frequestuency"];
  $lastModifiedAt=$_GET["lastModifiedAt"];
  $createdAt=$_GET["createdAt"];    
  $createdBy=$_GET["createdBy"];        
  $opPath=$_GET["opPath"];      
  $env=$_GET["env"];
  $file = fopen("log.txt","w");
  echo fwrite($file,"Job ID : ".$jobId."\n"."Job Status : ".$jobStatus."\n"."Display Name : ".$displayName."\n"."Name : "."\n"."Description : ".$description."\n"."Frequency : ".$frequency."\n"."Last Modified At".$lastModifiedAt."\n"."Created At".$createdAt."\n"."Created By : ".$createdBy);
  fclose($file);
  chmod("log.txt", 0777);
  $last_line = system('/usr/local/hadoop/bin/hadoop fs -put /var/www/html/log.txt /user/hduser/Alert/', $retval);
  $last_line = system('/usr/local/hadoop/bin/hadoop fs -ls /user/hduser/Alert/', $retval);
  echo '<pre>';
  $output2 = exec('hadoop fs -copyFromLocal /var/www/html/log.txt /user/hduser/Alert/Notify');
  echo '
    </pre>
    <hr />' . $last_line . '
    <hr />' . $retval;
        '<hr />' . $output1;

?>
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Akshay Hazari
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