#!/bin/bash
# Target directory
TARGET=COPY
for i in $(find . -iname *.txt)
do
mkdir -p "$TARGET/$(dirname ${i:2})"
head -100 $i > "$TARGET/${i:2}"
done

just for fun, A developer's playground diary.
#!/bin/bash
# Target directory
TARGET=COPY
for i in $(find . -iname *.txt)
do
mkdir -p "$TARGET/$(dirname ${i:2})"
head -100 $i > "$TARGET/${i:2}"
done