The software for the vast majority of Android applications is written and edited on a laptop PC or desktop PC.

However, there are several ways of writing and editing software directly on the Android device.^[1][2]

Some people think trying to write software directly on an Android device or other tablet is so different than writing it on a PC that it requires a new programming language supported by a completely new IDE.^[3]

Spartacus Rex has written a terminal IDE for Android^{[4][5] [6][7][8]} that takes a very traditional approach. It supports software development using a traditional command prompt; traditional text editors such as "vi"; the standard programming language for Android (Java); and the standard compiler for that language (gcc). The only thing non-traditional is that it runs them all directly on the Android device itself. (Even that can be seen as a return to a much older tradition of developing and compiling software on the same machine that runs the software).

JavaScript Hello World

The Terminal IDE was originally intended to be used for Java development, but it can also be used for JavaScript. Here is a quick "Hello World":

Tap the "Terminal IDE" icon.

Tap the "Terminal IDE" button.

At the Spartacus Rex command prompt,^[9] type

cd ~/sdcard ;
vim a.html

(I'm assuming you've done a little programming before, so you'll know when to press the Enter button at the end of the line).

Type "i" to get into insert mode, then enter a quick JavaScript program:

    <script>
    document.write( "hello." );
    alert("hi!");
    </script>

Then press the ESC button and ":wq" to save the program and quit back to the command prompt.

Hit the Home button and fire up your favorite web browser, and use this URL:

   file://sdcard/sdcard/a.html

You should see the "hi" alert pop up on top of a page saying "hello.".

$ adb -d forward tcp:8080 tcp:8080
$ telnet -e '' 127.0.0.1 8080

Using terminal IDE to ssh to a remote server

You can ssh from your Android device in Terminal IDE into your favorite servers. Type your username, at-sign, and domain name like so:

ssh dc@dreamhost.com

The first time you connect from a particular Android device to a particular server, you will see something like:

   Host 'dreamhost.com' is not in the trusted hosts file.
   (fingerprint md5 c4:ad:7f:ba:d8:23:d4:da:53:07:76:a2:7e:24:9d:67)
   Do you want to continue connecting? (y/n)

So type "y" and hit Enter

You must do this directly on the Android device's keyboard the first time you connect to a particular server. If you are telnetted to your phone from some other machine, you will get the error

   ssh: connection to dc@dreamhost.com:22 exited: Didn't validate host key

until you go back to the Android device and type the command directly from the Android device's keyboard.

Synchronization

The Terminal IDE includes "rsync", which is very useful for copying files, making backups, and quickly checking if files in two places are actually the same or not. ^[10]

Further reading

(Later: add a few words about using dropbearkey to generate a local private key that never leaves the smartphone, and the corresponding public key ... so we never need to type in a password to securely log in to a remote server.)^[10][11]

• The Terminal-IDE Organization
• "cloning from GitHub on Android using Terminal IDE"
• "Getting git Working on Android Devices" (Using Terminal IDE)
• "SSH and GIT on Android with Terminal IDE"