Simple script to create a quick horizontal collage appending three images

collage3.sh

#!/bin/bash

if [ -z $1 ] || [ -z $3 ]
then
    echo "Usage: ./collage3.sh image1.png image2.png image3.png"
else
    convert $1 -resize 40% resize1.png
    convert $2 -resize 40% resize2.png
    convert $3 -resize 40% resize3.png
    convert resize1.png resize2.png resize3.png +append collage.png
    display collage.png
    rm resize1.png
    rm resize2.png
    rm resize3.png
fi

Simple adaptation with only two images:

#!/bin/bash

if [ -z $1 ] || [ -z $2 ]
then
    echo "Usage: ./collage2.sh image1.png image2.png"
else
    convert $1 -resize 40% resize1.png
    convert $2 -resize 40% resize2.png
    convert resize1.png resize2.png +append collage.png
    display collage.png
    rm resize1.png
    rm resize2.png
fi