Solved

file.renameTo : linux v windows

Posted on 2004-08-01
9
745 Views
Last Modified: 2008-01-09
Can someone tell me why this works on Windows but not on Linux if renaming to a different partition :

import java.io.*;

public class moveFile {

public static void main(String[] args) {
File f = new File(args[0]);
System.out.println("Moving file "+args[0]+" to "+args[1]);
boolean ok = f.renameTo(new File(args[1]));
System.out.println("Move file was : "+ok);

}
}

running it on Linux with :

this works : java moveFile /opt/test1/testfile /opt/test2/testfile
this doesn't : java moveFile /opt/testfile /tmp/testfile

Thanks,

D.
0
Comment
Question by:damianharvey
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
  • 2
9 Comments
 
LVL 92

Expert Comment

by:objects
ID: 11690193
because renaming to a different partition is actually a copy and delete if across partitions.
0
 

Author Comment

by:damianharvey
ID: 11690559
So what stops this working? It isn't a permissions thing. I've chmod'ed all the dirs and files and run it as root.

What do most people do to get this functionality on Linux?
0
 
LVL 92

Expert Comment

by:objects
ID: 11690569
I don't think you can avoid doing a copy/delete.
what happens if you do a mv from command line?
0
Salesforce Made Easy to Use

On-screen guidance at the moment of need enables you & your employees to focus on the core, you can now boost your adoption rates swiftly and simply with one easy tool.

 

Author Comment

by:damianharvey
ID: 11690676
mv from command prompt is fine. No issues.

It is specific only to java. I can move files using the Linux Tools (eg. Konqueror) with no issues as well.

Just found a couple of links on google that suggest that it isn't possible for Java to rename across Partitions/Devices. Seems odd that such functionality would be crippled on Linux.
0
 
LVL 92

Expert Comment

by:objects
ID: 11690721
from the javadoc:

"Whether or not this method can move a file from one filesystem to another is platform-dependent"
0
 
LVL 24

Expert Comment

by:sciuriware
ID: 11691019
Since Windows 2000 the C-API supports renaming to be a move file.
So JAVA on Windows just tries an ordinary rename which is (sometimes!) carried out as a file move
on the OS-level. LINUX and UNIX don't.
The implementation of the rename operation is the cause of all this and not visible
from JAVA. The best you can do is write code that "copies & deletes" when a rename fails.
So I did.
;JOOP!
0
 
LVL 92

Accepted Solution

by:
objects earned 125 total points
ID: 11692003
A workaround would be to use Runtime.exec() to call mv
0
 

Author Comment

by:damianharvey
ID: 11722976
mv is the way to go I think. Here's the code I ended up using. I'm not sure why but the "-c" is required to get it working :

            if(!file.renameTo(archiveFile)) {
                        //Rename was not sucessful
                        if(File.separator.equals("/")) {
                              //You're on UNIX-LINUX-Solaris etc
                              try {
                                    
                                    String[] cmd = {"/bin/bash", "-c", "mv "+replaceSpaces(file.getAbsolutePath())+" "+replaceSpaces(archiveFile.getAbsolutePath())};
                                    log("Rename didn't work. Executing 'mv' command - "+cmd[0]+"; "+cmd[1]+"; "+cmd[2]);
                                    Process p = Runtime.getRuntime().exec(cmd);
                                    BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
                                    BufferedReader stdErr = new BufferedReader(new InputStreamReader(p.getErrorStream()));

                                    String content = "";
                                    
                                    while((content = stdInput.readLine()) != null) {
                                          log("Command std output : "+content);
                                    }
                                    stdInput.close();
                                    
                                    while((content = stdErr.readLine()) != null) {
                                          log("Command err output : "+content);
                                    }
                                    stdErr.close();
                                                                  
                                    log("Moved the file successfully using mv");
                                    
                                    return true;
                                    
                              } catch(IOException e) {
                                    log("IOException using mv on *IX System :"+e);
                              }
                        }
            } else {
                log("Moved the file successfully using rename");
                return true;
            }
0
 
LVL 24

Expert Comment

by:sciuriware
ID: 11723443
I found that it's faster (!?) and more controllable to copy a file yourself (don't ask me why/how).
So, I made a 'move' in JAVA because of system-independency:

     if(fileOld.renameTo(fileNew))
     {
            if(copy(fileOld, fileNew)) // true == OK
            {
                     fileOld.delete();
            }
     }

You can easily make your own copy show progress on the screen and copy filemode as well.
;JOOP!
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Bot application - advice 3 79
Java Eclipse Loop 3 45
Java class and jar 3 58
How to overcome error: The method of type x must override y or implement a supertype method 4 30
Introduction This article is the second of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers the basic installation and configuration of the test automation tools used by…
In this post we will learn different types of Android Layout and some basics of an Android App.
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
Viewers learn about the “for” loop and how it works in Java. By comparing it to the while loop learned before, viewers can make the transition easily. You will learn about the formatting of the for loop as we write a program that prints even numbers…
Suggested Courses

739 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question