There are two Python versions available in Pythonista 3

In Pythonista3, you can select Python version to execute your code – tap and hold the right triangle next to the file name and select 2.7 or 3.6. Usually 3.6 which is default should be fine, but in case you need to run a code written in Python 2.x you’ll need this feature.

Some commands on StaSh are written in Python 2.x

Some commands on StaSh, the shell-like powerful CLI add-on to Pythonista3, are written in Python 2. So, if you run it without specifying the version, you get the warning message below.

StaSh v0.7.2 on python 3.6.1
Warning: you are running StaSh in python3. Some commands may not work correctly in python3.
Please help us improving StaSh by reporting bugs on github.

In case you need to install Python 2 packages, you have to run StaSh in Python 2.7 and the warning message won’t appear.

StaSh v0.7.2 on python 2.7.12

Selecting the version everytime you launch StaSh is not smart, is it? 

Specify the Python version to execute your code

When you write a code, it is usually meant to be executed by a specific version, either 2.x or 3.x. Just like macOS or Linux, well, even simpler, you can specify the Python version at the first line – this method is called “Shebang”.

#! python2
# coding: utf-8
# Write your Python 2 codes below

Now you got the idea – yes, add the Shebang to a copy of the launch_stash.py and add it as a shortcut along with the original code so that you can quickly launch StaSh in your desired Python version.

There are lots of useful legacy codes/packages written in Python 2 you can find in pip, in the Internet or books. Don’t spend too much time to hand-code and convert into Python 3. Simply run as-is and/or have Pythonista3 convert it to version 3 – you can find Python 2 to 3 tool in the spanner menu: 

Enjoy!

Use SSH in Pythonista 3 (StaSh)

SSH in StaSh seems not to work if a passphrase is given to create keys. I found some hosting servers do not accept passphrase (password) to connect using SSH. In this post you can find a way to careate SSH keys in Pythonista 3 (SSH command in StaSh) with no passphrase.

Generate SSH keys in StaSh

$ ssh-keygen -t rsa -b 2048

Secret key and Public key are generated in the following path.

~/Documents/site-packages/stash/.ssh
$ ls
id_rsa id_rsa.pub

Copy the public key “id_rsa.pub” to your SSH server’s appropriate location.

SSH command to connect to your server

$ ssh username@username.xsrv.jp -p 10022

Above is an example to connect to XServer hosting server that I use. Change username, host name (“username.xsrv.jp” in this example) and port number (10022 in this case).

When you first run the ssh command in Pythonista 3, a terminal emulator “pyte” will be installed automatically. In this case you’ll see global name 'pyte' is not defined error message and need to quit and relaunch Pythonista 3.

Additional Notes – Set number of lines

Once the above is complete, you will want to add an alias (shortcut command) to the .stashrc file (Reference), copy the SSH keys to another SSH app, iOS device or computer. Make sure that you do not share “ids_rsa” the secret key file with anyone. Create .ssh folder in the same path if you use Pythonista 3 in another iOS device and place the ids_rsa file.

When connecting to a host, you will notice at least 3 lines from the top will be hidden as StaSh’s shortcut keys and iOS’s software keyboard will use 3 lines of the bottom of your screen. This is very annoying especially when you use ‘vi’ command to edit a file. To avoid this issue, one manual way is to use “stty” command to set your screen size (number of rows) every time you SSH to a server. Refer to examples below and find the best number for your environment.

$ stty rows 51 # Works best for iPad mini 2 + Bluetooth keyboard
$ stty rows 27 # Works best for iPhone 8 Plus with iOS software keyboard

How to install py-tree on Pythonista3 and use it easily.

With py-tree command, you can list files and directories in a tree view

[mysite]$ tree
.
|-- db.sqlite3
|-- manage.py
|-- mysite
|   |-- __init__.py
|   |-- settings.py
|   |-- urls.py
|   `-- wsgi.py
`-- polls
    |-- __init__.py
    |-- admin.py
    |-- apps.py
    |-- models.py
    |-- tests.py
    |-- urls.py
    |-- views.py
    `-- migrations
        |-- 0001_initial.py
        `-- __init__.py

Not only in Pythonista3 but also in many cases, you want to see all directories and files of your project in a better format in CLI, StaSh in Pythonista3’s case. The py-tree command is the solution.

Installation

You can easily install by running the following command in StaSh (type strings after the command prompt [stash]$ and hit [enter]).

[stash]$ pip install py-tree

Entering a dash “-” character in iPhone is a bit annoying so let’s create an alias tree.
In StaSh, you can create .stashrc file which works like .bashrc file for Linux’s  bash shell. Follow the example below to create an alias.

[stash]$ cd site-packages/stash/
[stash]$ la
.gitignore .stash_history .stash_tips .travis.yml CHANGES.md LICENSE README.md __init__.py bin docs getstash.py lib man stash.py system
[stash]$ touch .stashrc
[stash]$ echo "alias tree='py-tree'" >> .stashrc
[stash]$ cat .stashrc
alias tree='py-tree'
[stash]$ la
.gitignore .stash_history .stash_tips .stashrc .travis.yml CHANGES.md LICENSE README.md __init__.py bin docs getstash.py lib man stash.py system

Quit and relaunch Pythonista3 to let StaSh load the .stashrc file. Now you can use the tree command. Woo-hoo!

Create and edit files with different file extension than “xxx.py”.

You cannot create a file like “.stashrc” in Pythonista3 as it adds surfix “.py”. Also, once a file is created, it won’t appear in the file list to edit. So, when you need to create such a file, use touch command then use edit command to edit it in Pythonista’s Edit screen. ls -a or its alias la is the command to show invisible files in StaSh.

Summary