Center text with fmt and make
=============================


fmt
---

For years, plain text was the dominating format on Unix
systems.

To work with plain text files an ecosystem of powerful
utilities evolved.

fmt is one of those tools.

fmt can do some nifty things with plain text.

Using ed to edit my .plan file
------------------------------

Currently I edit my .plan file with Emacs, and then scp it
over to the box where it is served by finger.

It seems more logical to do the editing directly on that
system. But it is overkill to install Emacs for that.

So I looked at a way to do that with one of the text
utilities.

fmt can center lines. Empty lines are centered by a number
of spaces, from the left margin to the center of the line.

Which means that I can write the content in ed, and use
empty lines to add some vertical space.

fmt command
-----------

The fmt command to center the lines uses two switches:

* switch "-w" to set line length 
* switch "-c" to set line centering

The command will therefor be something like this:

  fmt -w 65 -c input-file > output-file

Makefile
--------

Because we want a nice header above the text, the
construction of the final .plan file consists of two
commands:

  cat nice-header > output-file
  fmt -w 65 -c input-file >> output-file

Typing two lines is of course out of the question, we need
a Makefile for that!
 
Here is the Makefile:

.plan: plan-header plan-content
        cat plan-header > .plan
        fmt -w 65 -c plan-content >> .plan

The lines below the first start with a tab (\t).

We this we can edit the contents of the .plan file with
ed, and run 'make' to construct the new version of the
file.

Automagically add the date
--------------------------

Now that we have automated the creation of the .plan file,
it is nice to extend this with automatic adding the
current date to the file.

This is quite easy:

   date -I | fmt -w 65 -c >> .plan

Let us add this to the Makefile:

.plan: plan-header plan-content
        cat plan-header >.plan
        fmt -w 65 -c plan-content >>.plan
        date -I | fmt -w 65 -c >> .plan

Don't forget that the lines below the first one all start
with a tab (\t).

Version control
---------------

Having a Makefile, version control can be made
effortless.

We use RCS for our version control.

Normally RCS is used interactively, but RCS can handle
batch check ins.

We use the following command for this:

  ci -q -t- -l -m'automatic check in' .plan

First, create a subdirectory named "RCS", then RCS will
put the version control file there.

Let us add this to the Makefile:

.plan: plan-header plan-content
        cat plan-header >.plan
        fmt -w 65 -c plan-content >>.plan
        date -I | fmt -w 65 -c >> .plan
        ci -q -t- -l -m'automatic check in' .plan

This gives us a nice history of our .plan file.

Some useful RCS commands:

rlog .plan 
This shows the version history.

rcsdiff -r1.3 -r1.1 .plan
This shows a diff between version 1.3 and version 1.1.

co -r1.1 .plan
Revert to version 1.1 of the file

Result
------

We have setup a .plan file that we can edit in ed. The
file has nicely looking centered lines.

A new version of the .plan file will be automagically
dated with the date of construction.

The .plan file is automagically checked in into RCS.  This
builds a nice history of the changes in our .plan file.

We can do all this on the actual system that runs the
finger daemon.  After issuing the 'make' command, we are
done, no scp is involved.

See the result at: finger matto@box.matto.nl


Last edited: $Date: 2023/08/04 07:51:16 $