Pronunciation of "lib"

I've been a computer programmer for many years, and recently my father has been learning computer programming. Programmers often times will use a folder called "lib."

Not a native English speaker, my father pronounced "lib" like *lib*eria - short for "library."

When I corrected him and told him it's pronounced "lib" like *li*t, he asked why if "lib" is supposed to be short for "library."

I couldn't think of an answer why. I thought of other words such as

• "pup", short for "puppy" is pronounced like the first part of puppy
• "mic", short for "microphone" is pronounced like the first part of microphone

Why is "lib" not pronounced like the first part of library?

Pronunciations of shortened forms and derived forms don't depend on those of originals. For instance, pronunciation ~ pronounce, professor ~ prof, library ~ lib, microphone ~ mic.

Trisyllabic laxing and precluster shortening should have shortened the first vowel in library; but it has not happened. That has to do with these: trisyllabic laxing does not apply to non-derived forms (Kiparsky's explanation); precluster shortening treats clusters like pr, br, etc as a single consonant. That's why we have historically long vowels in apron, April, acre (vs. Akron, OH), libra, maple (vs. apple). In the latter set, you can see ME open syllable lengthening as well.

We call it a /lib/ folder for the same reason we call the "/etc" folder /et see/ and not "et cetera". Or the same reason we pronounce "var" as /vahr/ not /vaer/ or "bin" as /bin/ and not /bine/ and proc is not /pross/.

First, it's easier to say, but more importantly, these abbreviations are no longer abbreviations. They have become words on their own right. "/lib" no longer really stands for "library", it means "lib". No one refers to an ".exe" file as an "exeh" (-cutable) and ".co.uk" is pronounced with a long O. You generally pronounce neologisms how they're spelled, not by what they mean.

A nontechnical example is the word bus. "Bus" is short for omnibus (accent on the NI). If we were to pronounce it as an abbreviation, we'd call it a /bis/, but it's it's own word - a /bus/.