Resize input files – but only if they exceed 800px width

resize.sh

#!/usr/bin/env bash

maxwidth=800

resize () {
    convert "$1" -resize $maxwidth "$2"
}

for image in large/*; do
    width=$(identify -format '%w' "$image")
    if [[ $width -gt $maxwidth ]]; then
        cmd=resize
    else
        cmd=cp
    fi
    $cmd "$image" "$(basename "$image")"
done