Download all files from a Slack workspace export folder.

slack-files-downloader.sh

#!/bin/bash 
#
# This script will browse a Slack export folder and download all files in a new /export folder
# 
# HOW TO:
# 1. As a Workspace admin, download an export of your Slack history (https://www.slack.com/services/export) 
# 2. Make sure you have jq installed (https://stedolan.github.io/jq/)
# 3. Place this file at the root of your Slack export folder, next to channels.json
# 4. Run `bash slack-files-downloader.sh` in your terminal
#
# OPTIONS
# -o Overwrite files if they already exist in destination folder, otherwise skip them.
# -s Do not show message when a file is skipped


while getopts "os" flag
do
    case $flag in
        o) overwrite=true;;
        s) silent=true;;
    esac
done

printf "\nSelect one specific file type to download or leave empty for any (e.g. mp3, binary, jpg, png):\n"
read usertype

printf "\nSelect a channel to look into or leave empty for all channels:\n"
read userchannel

for channel in $(cat channels.json | jq -rc '.[].name')
do
	if [[ $channel == $userchannel ]] || [[ -z $userchannel ]]
	then
		printf "\n============================================\nLooking into #$channel...\n============================================\n"

		for file in "$channel"/*.json
		do
			for a in $(cat $file | jq -c '.[].files[]? | [.title, .url_private_download, .filetype, .timestamp] | del(..|nulls)' | sed 's/ //g')
			do
				filetype=$(echo $a | jq -r '.[2]')

				if [[ $filetype == $usertype ]] || [[ -z $usertype ]] || [[ -z $filetype ]]
				then
					filename_raw=$(echo $a | jq -r '.[0]')
					
					filename=$(echo $filename_raw | sed -e 'y/āáǎàçēéěèīíǐìōóǒòūúǔùǖǘǚǜüĀÁǍÀĒÉĚÈĪÍǏÌŌÓǑÒŪÚǓÙǕǗǙǛÜ/aaaaceeeeiiiioooouuuuuuuuuAAAAEEEEIIIIOOOOUUUUUUUUU/')
					filename="${filename##*/}"
					
					if [[ ! -z $filename_raw  ]] && [[ $filename_raw != "null"  ]] 
					then		
						ts=$(echo $a | jq -r '.[3]')
						year=$(date -r $ts '+%Y')
						month=$(date -r $ts '+%m')

						# prefix filenames with date/time, as the same filename could be used
						# multiple times in different slack messages with different file contents.
						datetime=$(date -r $ts '+%Y%m%d-%H%M%S')
						filename="${datetime}-${filename}"
        
						if [ -f "export/$channel/$year/$month/$filename" ] && [[ $overwrite != true ]]
						then
							if [[ $silent != true ]]
							then
								printf "$filename already exists in destination folder. Skipping!\n"
							fi
							continue
						fi
						
						printf "Downloading $filename...\n"
							
						mkdir -p export/$channel/$year/$month

						url=$(echo $a | jq -rc '.[1]')
						
						
						printf "downloading to export/$channel/$year/$month/$filename with $ts\n"            
						curl --progress-bar $url -o "export/$channel/$year/$month/$filename"
					fi
				fi
			done
		done
	fi
done

I had to add:
channel=${channel//$'\r'/}
right before:
printf "\n============================================\nLooking into #$channel...\n============================================\n"

because there were some \r's sneaking in there and breaking all kinds of stuff.

and I also had to use datetime=$(date '+%H%M%S') because the datetime format you have gave me an empty string. Likewise with your year and month strings.

This is possibly all because I'm using Git Bash on Windows rather than a real bash client.

But now that I've done all that it seems pretty happy! Thanks!