#/bin/bash
#
# Sends an ascii-art text file to a parallel port needle/dot-matrix printer.
#
# Usage: ./txt2printr.sh [ascii-art.txt]
# Env:   PRINTER_DEV - printer device node (default: /dev/lp0)

infile="${1:-ascii-img.txt}"
dev="${PRINTER_DEV:-/dev/lp0}"

if [ ! -f "$infile" ]; then
    echo "txt2printr: file not found: $infile" >&2
    exit 1
fi

if [ ! -w "$dev" ]; then
    echo "txt2printr: cannot write to printer device: $dev" >&2
    echo "txt2printr: set PRINTER_DEV to override, or check permissions/parport module" >&2
    exit 1
fi

{
    printf '\x1b\x40'        # ESC @ - reset printer (ESC/P and IBM Proprinter compatible)
    sed 's/$/\r/' "$infile"  # CRLF line endings, needed for raw writes to avoid staircasing
    printf '\x0c'            # form feed - eject the page
} > "$dev"