It isn’t. There’s no vowel sound between sh and m. Think schmear.
Onset: shm. Nucleus: o. Coda: d. One syllable.
Onset: shm. Nucleus: o. Coda: d. One syllable.
https://en.wikipedia.org/wiki/Phonotactics#English_phonotact...
https://en.wikipedia.org/wiki/English_phonology#Phonotactics
/ʃm/ is not a legal onset in native English. (Let alone /tʃm/, which is how I pronounce "chmod" - two syllables, /tʃə 'mɔːd/.)
"Schmear" is a Yiddish loanword coming from German, where /ʃm/ is perfectly legal. So it's pronounceable by the human mouth, it's just a little awkward for English speakers.
/sm/ and /ʃr/ are both legal in English, so you might think of it as something like those. Can you pronounce "smear" or "shrine" as one syllable?
(I'm not sure /tʃm/ is valid in any language - words or names that start with "chm" seem to be Polish/Russian words transliterating /xm/.)
Oh it sure is in Croatian (and other Slavic languages), "tʃ" is written as "č". We even have slang words like "čmr-lji-ti" [t͡ʃmrʎiti]. "r" (rolling r) can function as a vowel.
The Dutch word “striktst” is of course also pronounced exactly how it's spelled, and in one syllable.
https://en.wikipedia.org/wiki/Swedish_phonology#Phonotactics
On-topic, I pronounce chmod as one syllable with "sh", like schmuck.
The trick is one continuous motion of pursing your lips, closing and then opening your mouth as you roll the constants together.
I wonder if the grandparent is French, because I would never have considered to pronounce chmod like this. Then again, I say C H mod and C H own, which apparently isn't the standard pronunciation, so what do I know!
I think what I’ve learned today is that no one pronounces any of these words even remotely the same!
...and while we’re at it, let’s do “char.”