Rsync in android

Question

Finally i am able to run super user commands in android program. Now i want to rsync a few files from my phone to my laptop and here comes the problem. rsync needs password to be given and i am not understanding how to give password of my laptop to this android program. There are ways in which rsync can be done using private/public keys. But what i want in general is that how do i feed input to rsync or for that matter any command through keyboard...Here i am attaching my program...

package com.iiitb.nikhil.sindhu;

import java.io.BufferedReader;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.*;
import android.util.*;


public class LinuxShellCommandAndroidProgramActivity extends Activity {
    /** Called when the activity is first created. */

    TextView tv;
    LinearLayout l;
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        try {
            Process process = Runtime.getRuntime().exec("/system/bin/su");
            DataOutputStream os = new DataOutputStream(process.getOutputStream());
            DataInputStream is=new DataInputStream(process.getInputStream());
            tv = new TextView(this);
            os.writeBytes("/system/xbin/rsync  /data/data/newfiles [email protected]:/home/sindhu/");
            String output=new String();
            String temp = new String();
            output=is.readLine();
            tv.setText(output);
            os.flush();
     } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
    }finally {
        setContentView(tv); }

    }
}

In the above i am trying to do rsync from my phone to my laptop..the above command would ask for the password but i am not understanding how to give input to this android program

Answer 1

if rsync asks for password (waiting for user input) you can write it from java to the executing proccess ("simulating" keyboard input)
like Can Java Runtime.exec another java program that uses stdin?

this is the output when you execute rsync in android shell without any arguments

there is a -password-file=FILE flag but I dont see any direct way to set the password

# rsync
rsync  version 3.0.6  protocol version 30
Copyright (C) 1996-2009 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 32-bit timestamps, 64-bit long ints,
    no socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, no ACLs, xattrs, iconv, symtimes

rsync comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
are welcome to redistribute it under certain conditions.  See the GNU
General Public Licence for details.

rsync is a file transfer program capable of efficient remote update
via a fast differencing algorithm.

Usage: rsync [OPTION]... SRC [SRC]... DEST
  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST:DEST
  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST::DEST
  or   rsync [OPTION]... SRC [SRC]... rsync://[USER@]HOST[:PORT]/DEST
  or   rsync [OPTION]... [USER@]HOST:SRC [DEST]
  or   rsync [OPTION]... [USER@]HOST::SRC [DEST]
  or   rsync [OPTION]... rsync://[USER@]HOST[:PORT]/SRC [DEST]
The ':' usages connect via remote shell, while '::' & 'rsync://' usages connect
to an rsync daemon, and require SRC or DEST to start with a module name.

Options
 -v, --verbose               increase verbosity
 -q, --quiet                 suppress non-error messages
     --no-motd               suppress daemon-mode MOTD (see manpage caveat)
 -c, --checksum              skip based on checksum, not mod-time & size
 -a, --archive               archive mode; equals -rlptgoD (no -H,-A,-X)
     --no-OPTION             turn off an implied OPTION (e.g. --no-D)
 -r, --recursive             recurse into directories
 -R, --relative              use relative path names
     --no-implied-dirs       don't send implied dirs with --relative
 -b, --backup                make backups (see --suffix & --backup-dir)
     --backup-dir=DIR        make backups into hierarchy based in DIR
     --suffix=SUFFIX         set backup suffix (default ~ w/o --backup-dir)
 -u, --update                skip files that are newer on the receiver
     --inplace               update destination files in-place (SEE MAN PAGE)
     --append                append data onto shorter files
     --append-verify         like --append, but with old data in file checksum
 -d, --dirs                  transfer directories without recursing
 -l, --links                 copy symlinks as symlinks
 -L, --copy-links            transform symlink into referent file/dir
     --copy-unsafe-links     only "unsafe" symlinks are transformed
     --safe-links            ignore symlinks that point outside the source tree
 -k, --copy-dirlinks         transform symlink to a dir into referent dir
 -K, --keep-dirlinks         treat symlinked dir on receiver as dir
 -H, --hard-links            preserve hard links
 -p, --perms                 preserve permissions
 -E, --executability         preserve the file's executability
     --chmod=CHMOD           affect file and/or directory permissions
 -X, --xattrs                preserve extended attributes
 -o, --owner                 preserve owner (super-user only)
 -g, --group                 preserve group
     --devices               preserve device files (super-user only)
     --specials              preserve special files
 -D                          same as --devices --specials
 -t, --times                 preserve modification times
 -O, --omit-dir-times        omit directories from --times
     --super                 receiver attempts super-user activities
     --fake-super            store/recover privileged attrs using xattrs
 -S, --sparse                handle sparse files efficiently
 -n, --dry-run               perform a trial run with no changes made
 -W, --whole-file            copy files whole (without delta-xfer algorithm)
 -x, --one-file-system       don't cross filesystem boundaries
 -B, --block-size=SIZE       force a fixed checksum block-size
 -e, --rsh=COMMAND           specify the remote shell to use
     --rsync-path=PROGRAM    specify the rsync to run on the remote machine
     --existing              skip creating new files on receiver
     --ignore-existing       skip updating files that already exist on receiver
     --remove-source-files   sender removes synchronized files (non-dirs)
     --del                   an alias for --delete-during
     --delete                delete extraneous files from destination dirs
     --delete-before         receiver deletes before transfer, not during
     --delete-during         receiver deletes during transfer (default)
     --delete-delay          find deletions during, delete after
     --delete-after          receiver deletes after transfer, not during
     --delete-excluded       also delete excluded files from destination dirs
     --ignore-errors         delete even if there are I/O errors
     --force                 force deletion of directories even if not empty
     --max-delete=NUM        don't delete more than NUM files
     --max-size=SIZE         don't transfer any file larger than SIZE
     --min-size=SIZE         don't transfer any file smaller than SIZE
     --partial               keep partially transferred files
     --partial-dir=DIR       put a partially transferred file into DIR
     --delay-updates         put all updated files into place at transfer's end
 -m, --prune-empty-dirs      prune empty directory chains from the file-list
     --numeric-ids           don't map uid/gid values by user/group name
     --timeout=SECONDS       set I/O timeout in seconds
     --contimeout=SECONDS    set daemon connection timeout in seconds
 -I, --ignore-times          don't skip files that match in size and mod-time
     --size-only             skip files that match in size
     --modify-window=NUM     compare mod-times with reduced accuracy
 -T, --temp-dir=DIR          create temporary files in directory DIR
 -y, --fuzzy                 find similar file for basis if no dest file
     --compare-dest=DIR      also compare destination files relative to DIR
     --copy-dest=DIR         ... and include copies of unchanged files
     --link-dest=DIR         hardlink to files in DIR when unchanged
 -z, --compress              compress file data during the transfer
     --compress-level=NUM    explicitly set compression level
     --skip-compress=LIST    skip compressing files with a suffix in LIST
 -C, --cvs-exclude           auto-ignore files the same way CVS does
 -f, --filter=RULE           add a file-filtering RULE
 -F                          same as --filter='dir-merge /.rsync-filter'
                             repeated: --filter='- .rsync-filter'
     --exclude=PATTERN       exclude files matching PATTERN
     --exclude-from=FILE     read exclude patterns from FILE
     --include=PATTERN       don't exclude files matching PATTERN
     --include-from=FILE     read include patterns from FILE
     --files-from=FILE       read list of source-file names from FILE
 -0, --from0                 all *-from/filter files are delimited by 0s
 -s, --protect-args          no space-splitting; only wildcard special-chars
     --address=ADDRESS       bind address for outgoing socket to daemon
     --port=PORT             specify double-colon alternate port number
     --sockopts=OPTIONS      specify custom TCP options
     --blocking-io           use blocking I/O for the remote shell
     --stats                 give some file-transfer stats
 -8, --8-bit-output          leave high-bit chars unescaped in output
 -h, --human-readable        output numbers in a human-readable format
     --progress              show progress during transfer
 -P                          same as --partial --progress
 -i, --itemize-changes       output a change-summary for all updates
     --out-format=FORMAT     output updates using the specified FORMAT
     --log-file=FILE         log what we're doing to the specified FILE
     --log-file-format=FMT   log updates using the specified FMT
     --password-file=FILE    read daemon-access password from FILE
     --list-only             list the files instead of copying them
     --bwlimit=KBPS          limit I/O bandwidth; KBytes per second
     --write-batch=FILE      write a batched update to FILE
     --only-write-batch=FILE like --write-batch but w/o updating destination
     --read-batch=FILE       read a batched update from FILE
     --protocol=NUM          force an older protocol version to be used
     --iconv=CONVERT_SPEC    request charset conversion of filenames
 -4, --ipv4                  prefer IPv4
 -6, --ipv6                  prefer IPv6
     --version               print version number
(-h) --help                  show this help (-h works with no other options)

Use "rsync --daemon --help" to see the daemon-mode command-line options.
Please see the rsync(1) and rsyncd.conf(5) man pages for full documentation.
See http://rsync.samba.org/ for updates, bug reports, and answers
rsync error: syntax or usage error (code 1) at main.c(1407) [client=3.0.6]

Answer 2

Assuming you have an rsync daemon on your laptop, you can use the RSYNC_PASSWORD environment variable or the --password-file option.

From the man page:

You can avoid the password prompt by setting the environment variable RSYNC_PASSWORD to the password you want to use or using the --password-file option. This may be useful when scripting rsync.

...

--password-file This option allows you to provide a password in a file for accessing a remote rsync daemon. Note that this option is only useful when accessing an rsync daemon using the built in transport, not when using a remote shell as the transport. The file must not be world readable. It should contain just the password as a single line.

Answer 3

As you mention, using public/private key is an alternative but this is the safest and optimal option. Even in Android it's easy to set up:

Usually you have a .ssh folder in the user home, but in Android you may not be able to use it (it depends on the user running the script, and in Android every app runs with another username).

Rsync has it's own service but it's commonly used only with SSH. You can use any SSH parameter in Rsync with the -e option. In your particular case, SSH has the -i option to specify a private key to authenticate, in case it works SSH (and therefore Rsync) will not ask for the password.

In your case this should be like this:

rsync -rltD --no-p -e "ssh -i /path_to_your_private_key" /path_to_local_files_on_android [email protected]:/path_on_remote_server

Then you should append your public key to the ~/.ssh/authorized_keys2 of your destination machine, in this example /home/user1/.ssh/authorized_keys2/path_to_your_private_key"

Another unsafe and NOT recommended option is using sshpas to directly enter your password:

rsync -rltD --no-p -e "sshpass -p password ssh" /path_to_local_files_on_android [email protected]:/path_on_remote_server

But I do not see the reason why you should not choose the first option.

This is working BTW with all SSH parameters. If you want to use Rsync on another port just use the option:

... -e "ssh -p 10022 -i /path_to_your_private_key" ...

If you seek for a general way to send keystrokes to apps you run, this is not possible if you don't have root access and run your app in this mode. You can run the command with busybox, but if busybox does not have an implemented way to accept keystrokes this won't be possible. You can though send an specific command, not requiring keystrokes and reading them from a local file for example, but this is not working on the case of passwords.

To do so you can use the "<" character after command to specify a text file with the keys that will be passed to the app. This is the changing the "standard input" to read from a local file.

Nevertheless the system with public/private key is much safer!