local filename = "temp.txt"

-- Create a file of length 26 bytes.
io.contents(filename, "abcdefghijklmnopqrstuvwxyz")
print($"Contents before truncation: {io.contents(filename)}")

-- Truncate file to 13 bytes.
io.contents(filename, io.contents(filename):sub(1, 13))
print($"Contents after truncation : {io.contents(filename)}")

-- Attempt to truncate file to 20 bytes.
io.contents(filename, io.contents(filename):sub(1, 20))
print($"Contents are still        : {io.contents(filename)}")