Why "no such file" error ??

[joe at actionline.com]

Recently I purchased a used Thinkpad T460 and I did
a fresh install of Linux Mint 20.1 that works ... except:

I also installed a "C" program called 'readin' that I have
used successfully for more than 30 years on several Linux
installs; but it does not work on on this Mint 20 install.

Instead, this error appears:
"/home/joe/bin/readin: No such file or directory"

That is weird because 'readin' is actually present
in my directory: /home/joe/bin

I have uploaded copies of the applicable files here:
*** https://vsiq.com/data/count/ *** In one of the
files named: why-no-such.pdf I have tried to explain
and demo the problem.

Someone suggested replacing 'readin' with "read -n1"
and that works in the small "count" example ...
however, it does not work in most of the other important
shell script applications in which I need 'readin' to work.

So the question remains, why that error message appears
when the named file is actually present in /home/joe/bin?

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