File Traversal

[Partheban Udayakumar]

Hi,

I need to traverse through all the files in a system. If i use walkFileTree and override the methods, it traverses only to a particular set of folders,even if i set the path to root folder("/"). If i use listRoots and listFiles and make a loop. I can traverse through only one folder in the root. Other folders are ignored. Please do not ask me to give the code, because I am not in a situation to reveal the code. Sorry for that. Can someone please help me with this?

[Richard Tookey]

Partheban Udayakumar wrote:Hi,

I need to traverse through all the files in a system. If i use walkFileTree and override the methods, it traverses only to a particular set of folders,even if i set the path to root folder("/"). If i use listRoots and listFiles and make a loop. I can traverse through only one folder in the root. Other folders are ignored. Please do not ask me to give the code, because I am not in a situation to reveal the code. Sorry for that. Can someone please help me with this?

Surely you just need to use your walkFileTree() code on each root obtained from listRoots() .

I don't understand "I am not in a situation to reveal the code" since I don't see how there can be anything proprietary in simple file tree walking code.

[Partheban Udayakumar]

Hi again Richard,

Thanks for answering. My problem is if I use walkFileTree I am not able to access all the files inside a folder. I am working in Ubuntu environment,so I have only one root. When I use walkFileTree, it searches only some folders, but I need to access the files and folders in the entire system. I did not use listRoots with walkFileTree. I tried to use listRoots and listFiles to get my own working code for file traversal,but it did not work. I ended up in traversing only the first folder in the root. If the folder I traversed has subfolders only the first subfolder is traversed,others are ignored and even other folders in the root other than the first folder is ignored.

[Richard Tookey]

I primarily use Ubuntu and have several Java programs that traverse parts of the file system and these work without problems. I suspect you are not running your code as root so you won't have permission to access directories directly beneath "/" . Solution - run your application as root using 'sudo' .

[Winston Gutkowski]

Partheban Udayakumar wrote:I am working in Ubuntu environment,so I have only one root.

I fear you and Richard are using the word "root" differently. There is a root user and a "directory root". I have never used walkFileTree, but I would expect that if it follows the general recursive pattern of trees, each directory is "its own root" - that is, there is nothing logically different about asking a tree walker to start at the root directory (/) or /usr/home/partheban.

I also fear, however, that Richard is right, and that you may be running into simple file/directory access issues. And if that's the case, I would definitely check with your sysadmin before you start running anything that does indeed traverse every directory in your system. /proc, for starters (don't know if Ubuntu uses it), is one that I'm not at all sure I would want to be ploughing through - or, as a sysadmin, letting anyone traverse - /dev would be another.

Winston

[Richard Tookey]

Winston Gutkowski wrote:

Partheban Udayakumar wrote:I am working in Ubuntu environment,so I have only one root.

I fear you and Richard are using the word "root" differently.

I use 'root' meaning both the 'root' user and the 'root' of the file system relying on the context to make it clear which is meant. I should be more explicit.

[Partheban Udayakumar]

According to me, root means root folder.

Richard, I am sorry I tried as root in terminal but still there is problem.

[Richard Tookey]

Partheban Udayakumar wrote:According to me, root means root folder.

Richard, I am sorry I tried as root in terminal but still there is problem.

Without us having a view of your code it would seem to be impossible to say what is wrong. Earlier I ran one of my utilities written in Java as the root user and it processed the whole file system without any problems. I still don't see what can be proprietary about your code that makes it impossible for you to post.

[Winston Gutkowski]

Partheban Udayakumar wrote:Richard, I am sorry I tried as root in terminal but still there is problem.

Question: have you tried
find / -type d -print
with the same sudo privileges?

If so, does it print out the same directories as you're getting with your Java program? If not, give us at least an example of a mismatch. That might help us; otherwise, like Richard says, we're kind of hamstrung, because we can't see your code.

Winston

[Partheban Udayakumar]

Here is my code:

public class Res extends SimpleFileVisitor<Object> {

    public static void main(String[] args) {

        try {
            final Path startPath = Paths.get("/");
            Files.walkFileTree(startPath, new SimpleFileVisitor<Path>() {
                /*@Override
                public FileVisitResult preVisitDirectory(Path dir,
                   BasicFileAttributes attrs)
                throws IOException {
                System.out.println(">>>>Dir : " + dir);
                return FileVisitResult.CONTINUE;
                }*/

                @Override
                public FileVisitResult visitFile(Path file,
                     BasicFileAttributes attrs)
                throws IOException {


                    //System.out.println(file.toString());

                    //uses file "nf" to write in it
                    File fa = new File(
                       "/home/xsec6/Desktop/Parthe/nf");

                    PrintWriter pw = new PrintWriter(
                       new FileWriter(fa, true));
                    File f = new File(file.toString());
                    
                   // gets filename and the attributes
                    String ff = f.getName();
                    String a = "$#";
                    String ct = attrs.creationTime().toString();
                    String lat = attrs.lastAccessTime().toString();
                    String lmt = attrs.lastModifiedTime().toString();
                   //appends it to the file
                    pw.append(ff + a + ct + a + lat + a + lmt + "\n");
                    pw.close();

                    return FileVisitResult.CONTINUE;
                }
            });
        } catch (Exception ex) {
         System.out.println(ex);
        ex.printStackTrace();
        }

    }
}

But I am not able to access all the system files with this code. I tried all the suggested ways

[Winston Gutkowski]

Partheban Udayakumar wrote:Here is my code:

You still haven't told us what happens. Do you get an Exception? Do you get any messages?

Like I say, I've never used it, but from the docs it looks to me as though you could possibly help yourself out by overriding the visitFileFailed() method and using it to print out relevant information before continuing.

Also: Please DontWriteLongLines. I makes your thread very hard to read. I've broken yours up this time, but for future reference:
80 characters max.

Thanks.

Winston

[Richard Tookey]

Winston Gutkowski wrote:

Partheban Udayakumar wrote:Here is my code:

You still haven't told us what happens. Do you get an Exception? Do you get any messages?

Like I say, I've never used it, but from the docs it looks to me as though you could possibly help yourself out by overriding the visitFileFailed() method and using it to printing out relevant information before continuing.

Also: Please DontWriteLongLines. I makes your thread very hard to read. I've broken yours up this time, but for future reference:
80 characters max.

Thanks.

Winston

Exactly ! As expected the code as it stands throws

Exception in thread "main" java.nio.file.AccessDeniedException:  some-file-path

and terminates. As you say, this is simply solved by implementing the visitFileFailed() method, doing whatever the OP needs to do and returning FileVisitResult.CONTINUE .

I don't understand why the test class extends SimpleFileVisitor<Object> . I don't understand what in this code can be considered 'proprietary'.