TN3270 on MacOS Catalina: Connect to IBM Mainframe easily

In this article I will explain how to set up connection to IBM Mainframe from MacOS Catalina, but let’s start from small piece of history.

Root of the problem

With release of Catalina many things happened, including tons of bugs on its release, but one of the most groundbreaking was disabling support of 32-bit applications, which for most of the Mac-based mainframers (here and after means users of the IBM Mainframe) meant one sad thing: they won’t be able to use TN3270 from Brown University anymore which was a free and recommended way to interact with mainframe. Of course there’re alternatives, like Mocha TN3270 or ZOC, but they’re not free, so what should we do? Install c3270 on your Mac, of course!

Installation

Open page with installation script provided by IBM and copy it.

Open your terminal and type the following commands:

cd ~/Downloads
mkdir temp
cd temp

It will create temporary folder for us, now let’s create a text file where we will place our script:

touch script
open script

In opened text editor paste and save text which we’ve copied earlier. Now let’s run this script, as you can see it’s Z Shell script, so we should run it accordingly:

sudo zsh script

After that you will see sequence of commands and, probably, the installation of XCode Command Line Tools, if don’t have it installed yet. To check that your installation has finished correctly type:

which c3270
>>> /usr/local/bin/c3270 

If it doesn’t return you anything try to restart the terminal. After that you will be able to use c3270 so let’s do our test connection. Type the following (no http/https and ports are required, just use the hostname or ip address):

c3270 <hostname/ip address>

After that you should see the following picture:

As they ask type and press enter:

logon <your userid>

Next screen will ask for your password:

Type it in and that’s it, you’re ready to go!

Now you are able to use TN3270 from your Mac, so good luck with mainframe and have fun!