Terminal

This one is almost a no-brainer. Everyone who knows Android is Linux underneath (and who knows Linux) normally heads for a command line to check things out right off the bat. You can get access via ADB, but having direct access right on the device is killer. This app gives you access to the command shell built into the device.

Market link: Android Terminal Emulator

ConnectBot

ConnectBot is an SSH client application for your phone. It’s a fantastic application for quick access to remote systems. If you’re on a device without a physical keyboard it’s not quite as slick to use (I wouldn’t recommend trying to use vi on a remote system from a Samsung Galaxy for instance), but for quick tasks it can be fantastically convenient.

Market link: ConnectBot

Advanced Task Killer

This seems to be a pretty consistent tool in most advanced user’s toolboxes. Android apps can keep running in the background. Most of the ones that do give you good ways to control when they run, and the OS itself does a generally good job of managing them. But if you tend to poke around with lots of apps and try out all the different tools you hear about you’re bound to run across one or two that misbehave every once in a while. When you do, Advanced Task Killer can help you figure out what’s going on and set things right again.

Market link: Advanced Task Killer

Astro File Manager

This is the free version of a file manager application. There’s a paid version that includes a ton of additional features, but so far I’ve stuck with the free version. Nice interface for browsing around and seeing what files are on your device. Includes built in viewers that generally handle text and image files well.

Market link: Astro File Manager

Dropbox

Dropbox is a free service that lets you store files online and sync them between systems. If you don’t already have an account and want to try it out please sign up using this affiliate link (I get credit for the signup and get some free space on Dropbox if you do). They have an Android application that allows viewing, downloading, or uploading. Together with an application like Astro you can upload arbitrary files from your phone to Dropbox as well. From within Dropbox use upload from the menu, and then select any file and use Astro to complete the action.

Market link: Dropbox

Scripting Layer for Android

An app that allows for accessing native Android functions from multiple scripting languages. Once you install SL4A you can use it to pull down interpreters. A bunch are available, like Unix shell, Python, Perl, Ruby, and others. Then you can run scripts in those languages that tie into Android specific functions. SL4A is not available in the Marketplace however, so use the info on the Google Project page to download the apk directly. If you’re on an AT&T device like the Samsung Captivate and haven’t hacked it to allow direct third party installs you’ll have to load the apk files using ADB. As of right now, it seems you need to download the core SL4A app and then separate downloader shims for the different interpreters. The base sl4a seems to only have shell installed by default. But once you install something like python_for_android_r1.apk and click install within that app you’ll get Python support in sl4a.

The application interface itself is pretty simple. When it first loads up you won’t have any interpreters besides shell. If you go into the View menu, select interpreters, and then select Add from the menu under there you can add other interpreters. The interpreters generally come with example scripts, which will show up in the main list view once they’re loaded:

There’s a preferences screen, which covers mostly visual options:

If you long press on a script you have an option to edit it:

The editor that comes up is just a simple but effective textbox, so at least you can edit scripts in place on the device:

And then you can run a script, in this place displaying a toast message over the keyboard when I run the hello world program:

• Handle intents
• Start activities
• Make phone calls
• Send text messages
• Scan bar codes
• Poll location and sensor data
• Use text-to-speech

1. Follow the instructions to download and build Android from source. Follow the whole thing (I had to create a case-sensitive disk image and all), including the actual build step. Otherwise you won’t have the libraries necessary and agcc will error out when you try to run it.
2. Add the prebuilt/darwin-x86/toolchain/arm-eabi-4.2.1/bin subdirectory of where ever you built the source to your PATH, add it to your .bash_profile if you want.
3. Download the agcc wrapper script, put it somewhere in your path, and make it executable.

Now you should be ready to compile a program and download it to your phone. This was my test app:

#include <stdio.h>

int main( int argc, char **argv ) {
  printf("Hello from Droid Hacks!\n");
  return 0;
}

And you should be able to compile it with “agcc hello.c -o hello” and end up with a hello executable:

~ > agcc hello.c -o hello
~ > file hello
hello: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), not stripped
~ >

And you can move the file across to the phone and run it. You’ll have to make a directory to push it into. The sdcard is marked as noexec, so you can’t run stuff from there. And the data directory has more restrictive permissions. So you’ll have to su and create a directory on the data partition, and relax the perms on that directory:

~ > adb shell
$ su
# mkdir /data/droidtest
# chmod 777 /data/droidtest
# exit
$ exit
~ > adb push hello /data/droidtest
418 KB/s (6747 bytes in 0.015s)
~ > adb shell
$ cd /data/droidtest
$ ls -l
-rwxrwxrwx shell    shell        6747 2009-05-27 08:56 hello
$ ./hello
Hello from Droid Hacks!
$

And of course you can run the same thing from the terminal on your device as well:

• mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system
• cd /system/bin
• cat sh > usu
• chmod 4755 usu

Some of the instructions I found online suggested just calling the new binary su, but I was concerned about that overriding the default su depending on what path is getting used. So I just created a whole name “user su” which won’t reject the handset user when I try to change to root: