output files using $PAGER if the number of lines is grater or equal than $LINES, or output using cat.

pageless

#!/bin/bash
pname=$(basename "$0")

while true; do
  case "$1" in
  -l) lines="$2"; shift 2;;
  -*) echo "$pname: '$1': no such option.">&2; shift;;
  *) break;;
  esac
done
test -z "$lines" && lines=$(tput lines) 

test $# -le 0 && set -- -
buffer=$(mktemp -q -t "$pname.XXXXXXXX")
trap 'rm -r "$buffer"' 1 2 3 15 EXIT
cat "$@" >"$buffer"
if [ $(cat "$buffer" | wc -l) -lt $lines ]; then
  cat "$buffer"
else
  cat "$buffer" | ${PAGER:-less}
fi

~Makefile.snippet

## Makefile

XPAGER = $(shell which pageless || echo $${PAGER:-less})

output:
  cat Contents.txt | $(XPAGER)