I use PCB to design PCBs, and I recently needed to embed a list of drills and their uses in a plain text file. PCB's drill file looks like this:

M48
INCH
T72C0.010
T71C0.015
T70C0.067
T69C0.039
T68C0.030
T67C0.046
T66C0.138
%
T72
X010249Y009035
X010249Y005886
X010268Y008256
X010268Y007075
X010268Y005107

...and I wrote drilltable.tcl to generate tables like this:

|------------+----------------------+------------|
| Tool       | Hole size (inch)     | Count      | 
|------------+----------------------+------------|
| T72        | 0.010                | 218        | 
| T71        | 0.015                | 95         | 
| T68        | 0.030                | 3          | 
| T69        | 0.039                | 10         | 
| T67        | 0.046                | 15         | 
| T70        | 0.067                | 1          | 
| T66        | 0.138                | 4          | 
|------------+----------------------+------------|

This borrows from an excellent usage example of Tcl's format command at the Tclers Wiki.

Download ActiveTcl from ActiveState

ActiveTcl provides teacup, which is a client for the TEApot package server. The Tclers wiki provides much more information about all this.

I unpack the downloaded file in some temporary directory. There's an install.sh file in the root of the unpacked archive.

$ sudo ./install.sh

...will start the graphical installer. I just accept the default /opt/ActiveTcl-8.6 installation directory and accept all the terms.

View the available packages list

With the default installation directory, I need to be root to use teacup. I also need to add it to my path.

$ sudo su
# PATH=/opt/ActiveTcl-8.6/bin:$PATH
# teacup list

See the edit below for more about problems with permissions.

Install your package

I want to install math::statistics, so

# teacup install math::statistics

<snip>

Retrieving package math::statistics 1.0 tcl ...@ http://teapot.activestate.com ... Ok

Installing into /opt/ActiveTcl-8.6/lib/teapot

Installing package math::statistics 1.0 tcl

Check your work

Start tclsh to make sure you can require math::statistics as an ordinary user.

# exit
$ PATH=/opt/ActiveTcl-8.6/bin:$PATH
$ tclsh
% package require math::statistics
1.0

...and that's success! Of course, you can make your life easier by adding the PATH command to your .bashrc or .bash_profile script.

Edit on Saturday, September 24, 2016

I could not install ActiveTcl in a way that allowed an ordinary user to use teacup. I tried installing everything into /home/john/opt instead of /opt, but teacup then created a ~/.teapot directory owned by root. So I guess users of "locked down" systems will need to find another way to get the packages they need.