Download images from resource servers such as wp-content.

download-img.sh

#!/bin/bash

# Link to download resource as first argument
base_url=$1

# end
# Number to stop the incrementing id
end_id=$2

# starting id, will default to 1 if empty
start_id=$3

# output file will be downloaded here
download_directory=$4

if [ $# -eq 0 ]
then
echo "No arguments supplied"
fi

if [[ -z $start_id ]]; then
    start = 1
fi

for i in $(seq $start_id $end_id) ; do
# Default id format is 0001, change to your desired format
    _U=`printf $base_url"%04d".jpg $i`
    echo "Downloading" $_U
    wget -a log$limit -P $download_directory --server-response $_U 
done
echo "Done"

multiple-download.sh

./download-img.sh $base_url_1 ${end_id} ${start_id} your_directory &
./download-img.sh $base_url_2 ${end_id} ${start_id} your_directory &
./download-img.sh $base_url_3 ${end_id} ${start_id} your_directory && fg

This is not a multithreaded solution.

If you want to download in multiple processes then edit multiple-download.sh to fit your needs

Script reference from this guide

This script only used for downloading files with incremental ID,
Hashed ID will not work