At least in Unix, '|' is not a valid filename, so -p '|' will always be false: "Is '|' a pipe? No.". So the ASCII representation of a pipe, '|', is never a pipe itself, which is exactly what Magritte meant with his painting.
In reply to Re^3: This is not a pipe
by pijll
in thread This is not a pipe
by TGI
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