How can I get a list of all mounted filesystems in Java on Unix?

Question

I\'m running Java on a Unix platform. How can I get a list of all mounted filesystems via the Java 1.6 API?

I\'ve tried File.listRoots() but that return

Answer 1

In Java7+ you can use nio

import java.io.IOException;
import java.nio.file.FileStore;
import java.nio.file.FileSystems;

public class ListMountedVolumesWithNio {
   public static void main(String[] args) throws IOException {
      for (FileStore store : FileSystems.getDefault().getFileStores()) {
         long total = store.getTotalSpace() / 1024;
         long used = (store.getTotalSpace() - store.getUnallocatedSpace()) / 1024;
         long avail = store.getUsableSpace() / 1024;
         System.out.format("%-20s %12d %12d %12d%n", store, total, used, avail);
      }
   }
}

Answer 2

You can try use follow method for resolve issue:

My code

public List<String> getHDDPartitions() {
    try {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream("/proc/mounts"), "UTF-8"));
        String response;
        StringBuilder stringBuilder = new StringBuilder();
        while ((response = bufferedReader.readLine()) != null) {
            stringBuilder.append(response.replaceAll(" +", "\t") + "\n");
        }
        bufferedReader.close();
        return Lists.newArrayList(Arrays.asList(stringBuilder.toString().split("\n")));
    } catch (IOException e) {
        LOGGER.error("{}", ExceptionWriter.INSTANCE.getStackTrace(e));
    }
    return null;
}

public List<Map<String, String>> getMapMounts() {
    List<Map<String, String>> resultList = Lists.newArrayList();
    for (String mountPoint : getHDDPartitions()) {
        Map<String, String> result = Maps.newHashMap();
        String[] mount = mountPoint.split("\t");
        result.put("FileSystem", mount[2]);
        result.put("MountPoint", mount[1]);
        result.put("Permissions", mount[3]);
        result.put("User", mount[4]);
        result.put("Group", mount[5]);
        result.put("Total", String.valueOf(new File(mount[1]).getTotalSpace()));
        result.put("Free", String.valueOf(new File(mount[1]).getFreeSpace()));
        result.put("Used", String.valueOf(new File(mount[1]).getTotalSpace() - new File(mount[1]).getFreeSpace()));
        result.put("Free Percent", String.valueOf(getFreeSpacePercent(new File(mount[1]).getTotalSpace(), new File(mount[1]).getFreeSpace())));
        resultList.add(result);
    }
    return resultList;
}

private Integer getFreeSpacePercent(long total, long free) {
    Double result = (Double.longBitsToDouble(free) / Double.longBitsToDouble(total)) * 100;
    return result.intValue();
}

Answer 3

You can call the getmntent function (use "man getmntent" to get more information) using JNA.

Here is some example code to get you started:

import java.util.Arrays;
import java.util.List;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;

public class MntPointTest {
    public static class mntent extends Structure {
        public String mnt_fsname; //Device or server for filesystem
        public String mnt_dir; //Directory mounted on
        public String mnt_type; //Type of filesystem: ufs, nfs, etc.
        public String mnt_opts;
        public int mnt_freq;
        public int mnt_passno;

        @Override
        protected List getFieldOrder() {
            return Arrays.asList("mnt_fsname", "mnt_dir", "mnt_type", "mnt_opts", "mnt_freq", "mnt_passno");
        }
    }

    public interface CLib extends Library {
        CLib INSTANCE = (CLib) Native.loadLibrary("c", CLib.class);

        Pointer setmntent(String file, String mode);
        mntent getmntent(Pointer stream);
        int endmntent(Pointer stream);
    }

    public static void main(String[] args) {
        mntent mntEnt;
        Pointer stream = CLib.INSTANCE.setmntent("/etc/mtab", "r");
        while ((mntEnt = CLib.INSTANCE.getmntent(stream)) != null) {
            System.out.println("Mounted from: " + mntEnt.mnt_fsname);
            System.out.println("Mounted on: " + mntEnt.mnt_dir);
            System.out.println("File system type: " + mntEnt.mnt_type);
            System.out.println("-------------------------------");
        }

        CLib.INSTANCE.endmntent(stream);
    }
}

Answer 4

I was already on the way to using mount when @Cozzamara pointed out that's the way to go. What I ended up with is:

    // get the list of mounted filesystems
    // Note: this is Unix specific, as it requires the "mount" command
    Process mountProcess = Runtime.getRuntime ().exec ( "mount" );
    BufferedReader mountOutput = new BufferedReader ( new InputStreamReader ( mountProcess.getInputStream () ) );
    List<File> roots = new ArrayList<File> ();
    while ( true ) {

        // fetch the next line of output from the "mount" command
        String line = mountOutput.readLine ();
        if ( line == null )
            break;

        // the line will be formatted as "... on <filesystem> (...)"; get the substring we need
        int indexStart = line.indexOf ( " on /" );
        int indexEnd = line.indexOf ( " ", indexStart );
        roots.add ( new File ( line.substring ( indexStart + 4, indexEnd - 1 ) ) );
    }
    mountOutput.close ();

Answer 5

OSHI (Operating System and Hardware Information library for Java) can be useful here: https://github.com/oshi/oshi.

Check out this code:

@Test
public void test() {

    final SystemInfo systemInfo = new SystemInfo();
    final OSFileStore[] fileStores = systemInfo.getOperatingSystem().getFileSystem().getFileStores();
    Stream.of(fileStores)
    .peek(fs ->{
        System.out.println("name: "+fs.getName());
        System.out.println("type: "+fs.getType() );
        System.out.println("str: "+fs.toString() );
        System.out.println("mount: "+fs.getMount());
        System.out.println("...");
    }).count();

}

Answer 6

Java doesn't provide any access to mount points. You have to run system command mount via Runtime.exec() and parse its output. Either that, or parse the contents of /etc/mtab.