readdir returns dat.txt, because it finds CSV/dat.txt. -f, on the other hand, runs on dat.txt only, i.e. ./dat.txt. ! -d is true for files that exists in CSV, but do not exist in the current directory.
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re^3: Scanning a directory's files for readability by choroba
in thread Scanning a directory's files for readability by Phoebus2000

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