Android – How to delete a system file from an Android App

androidshellsystem

I'm using Root Tools and I'm not getting too far with it…
I want to have access to delete files from /system/app and other directories that require root. I would love to do it programmatically through Java, but if I can do it through shell commands, that's OK. Too. My phone is rooted. Here's what I've tried so far.

RootTools.remount("/system", "rw");
                 try {
                    RootTools.sendShell("rm /system/app/Videos.apk", -1);
                } catch (IOException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (RootToolsException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (TimeoutException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }

I've also tried:

 public static void sendShell(List<String> cmds) throws Exception {
        Process process = Runtime.getRuntime().exec("su");
        DataOutputStream os = new DataOutputStream(process.getOutputStream());

        for (String tmpCmd : cmds) {
                os.writeBytes(tmpCmd+"\n");
        }

        os.writeBytes("exit\n");
        os.flush();
        os.close();

        process.waitFor();
    }

I have no idea what to do from here…

Best Answer

Based on our conversations it looks like you need a different rom as there were issues remounting partitions on your device.

I would bet that flashing a new rom would alleviate this issue and allow RootTools to properly remount /system as rw and allow you to delete your file.

Related Solutions

Ruby – How to call shell commands from Ruby

This explanation is based on a commented Ruby script from a friend of mine. If you want to improve the script, feel free to update it at the link.

First, note that when Ruby calls out to a shell, it typically calls /bin/sh, not Bash. Some Bash syntax is not supported by /bin/sh on all systems.

Here are ways to execute a shell script:

cmd = "echo 'hi'" # Sample string that can be used

Kernel#` , commonly called backticks – `cmd`

This is like many other languages, including Bash, PHP, and Perl.

Returns the result (i.e. standard output) of the shell command.

Docs: http://ruby-doc.org/core/Kernel.html#method-i-60
```
value = `echo 'hi'`
value = `#{cmd}`
```
Built-in syntax, %x( cmd )

Following the x character is a delimiter, which can be any character. If the delimiter is one of the characters (, [, {, or <, the literal consists of the characters up to the matching closing delimiter, taking account of nested delimiter pairs. For all other delimiters, the literal comprises the characters up to the next occurrence of the delimiter character. String interpolation #{ ... } is allowed.

Returns the result (i.e. standard output) of the shell command, just like the backticks.

Docs: https://docs.ruby-lang.org/en/master/syntax/literals_rdoc.html#label-Percent+Strings
```
value = %x( echo 'hi' )
value = %x[ #{cmd} ]
```
Kernel#system

Executes the given command in a subshell.

Returns true if the command was found and run successfully, false otherwise.

Docs: http://ruby-doc.org/core/Kernel.html#method-i-system
```
wasGood = system( "echo 'hi'" )
wasGood = system( cmd )
```
Kernel#exec

Replaces the current process by running the given external command.

Returns none, the current process is replaced and never continues.

Docs: http://ruby-doc.org/core/Kernel.html#method-i-exec
```
exec( "echo 'hi'" )
exec( cmd ) # Note: this will never be reached because of the line above
```

Here's some extra advice: $?, which is the same as $CHILD_STATUS, accesses the status of the last system executed command if you use the backticks, system() or %x{}. You can then access the exitstatus and pid properties:

$?.exitstatus

For more reading see:

Python – How to execute a program or call a system command

Use the subprocess module in the standard library:

import subprocess
subprocess.run(["ls", "-l"])

The advantage of subprocess.run over os.system is that it is more flexible (you can get the stdout, stderr, the "real" status code, better error handling, etc...).

Even the documentation for os.system recommends using subprocess instead:

The subprocess module provides more powerful facilities for spawning new processes and retrieving their results; using that module is preferable to using this function. See the Replacing Older Functions with the subprocess Module section in the subprocess documentation for some helpful recipes.

On Python 3.4 and earlier, use subprocess.call instead of .run:

subprocess.call(["ls", "-l"])

Best Answer

Related Solutions

Ruby – How to call shell commands from Ruby

Python – How to execute a program or call a system command

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