fatcp

#! /usr/bin/bash

# Script for safe copying to FAT32 filesystems.
# All bad characters are replaced by '_' (underscore) when copying.
# File conflicts (e.g. 'foo?' and 'foo:' are both mapped to 'foo_') are not checked - using 'cp -i' is recommended.

# Some resources:
# http://askubuntu.com/questions/11634/how-can-i-substitute-colons-when-i-rsync-on-a-usb-key
#
# Simple (stupid) alternative:
# find -type f -name '*.pat' -print0  | tar -c -f - --null --files-from - | tar -C /path/to/dst -v -x -f - --show-transformed --transform 's/?/_/g'
#

# two arguments are accepted
if [[ $# -ne 2 ]]; then
    echo "Usage: $0 <src path> <dst path>"
    exit 1
fi

base=$(realpath "$1")
basedir=$(dirname "$base")
dst=$(realpath "$2")

# $dst must be existing dir
if [[ ! -d "$dst" ]]; then
    echo "Target directory '$dst' does not exist."
    exit 1
fi

# 'cp' alias
CP="cp -i --preserve=all"
# characters that will be replaced with '_'
BADCHARS='<>|;:!?"*\+'

# enhance globbing
shopt -s dotglob globstar

# function creating target file/dir name
mk_target() {
    local target=${1#"$basedir"}
    echo "$dst/${target//[$BADCHARS]/_}"
}

# dirs and files are handled differently
if [[ -d "$base" ]]; then
    target=$(mk_target "$base")
    mkdir "$target"
    for src in "$base"/**/*; do
        target=$(mk_target "$src")
        if [[ -d "$src" ]]; then
            mkdir -p -- "$target"
        elif [[ "$src" != "$target" ]]; then
            $CP -- "$src" "$target"
        fi
    done
elif [[ -f "$base" ]]; then
    target=$(mk_target "$base")
    if [[ "$src" != "$target" ]]; then
        $CP -- "$base" "$target"
    fi
fi