line1
line2
-n
line4
-en
line6
-x
line8

while IFS= read line
do
  echo "$line"
done < input.txt

echo_(){
  ( IFS=" "; printf "%s\n" "$*" )
}

while IFS= read line
do
  echo_ "$line"
done < input.txt

# Simple echo
echo_(){
  ( IFS=" "; printf "%s\n" "$*" )
}

# Portable echo -n
echo_n() {
  ( IFS=" "; printf "%s" "$*" )
}

# Portable echo -e
echo_e() {
  ( IFS=" "; printf "%b\n" "$*" )
}

# Portable echo -ne
echo_ne() {
  ( IFS=" "; printf "%b" "$*" )
}

alias echo_en=echo_ne