#!/bin/bash
echo .

echo This bash script demonstrates a spurious message when cp -p is used to copy files to a MSDOS FAT32 formatted drive.

echo This script is run on the Terminal application of a MacBook Pro [OS X 10.11.6] [ darwin ].

echo We start with two identical files, test1,txt and test2.txt to be copied to a flash drive.

echo test1.txt has NOT been recently edited and the command produces NO error message.

cp -p -v test1.txt /VOLUMES/KMOVER/testout1.txt

echo .

echo  test2.txt is a recently edited file so the below produces a spurious error message even though the copy works.

cp -p -v test2.txt /VOLUMES/KMOVER/testout2.txt

echo The error message above is expected to appear as follows:

echo "cp: fchflags: /Volumes/KMOVER/testout2.txt: Invalid argument"

echo .

echo The ls -la command results below shows that both copies worked,  all .txt files have exactly the same size, and their modification date/times are preserved.
ls -la test*.txt

ls -la /VOLUMES/KMOVER/test*.txt

echo .

echo So far, I have noticed three conditions that cause this spurious message for a cp.
echo Without any one of these, the spurious message is not present.

echo 1. The source file has a recent date [less than a few hours old].

echo 2. The -p parameter is specified to preseve the modification date.

echo 3. The copy is to an MSDOS FAT32 flash drive.

echo .

echo I suspect this is a bug in cp or fchflags.

echo Can anyone please confirm this and advise on what to do about it.