That's what I get when I try to run mov-2-mp4.sh:

$ sudo ./mov-2-mp4.sh
Usage: grep [OPTION]... PATTERN [FILE]...
Try 'grep --help' for more information.

How can I fix this?

My settings:

# Variables
root_folder="/data/nextcloud/"                                     # Where to scan
installation_path="/var/www/html"                                  # Full path where nextcloud is installed, must not end with '/'
old_extension=".mov"                                               # e.g. ".mov"
new_extension=".mp4"                                               # e.g. ".mp4"
safe_mode=true                                                     # true = rename file to .mov-old, false = permanently delete old .mov file
ignoregrep=""                                                      # Ignore stderr messages from find that match this grep (e.g. 'Permission denied' for some folder name)
instance_id=$(openssl rand -hex 4)
append_extension=-wip-$instance_id

~# bash /mnt/dietpi_userdata/downloads/mov-2-mp4.sh
/mnt/dietpi_userdata/downloads/mov-2-mp4.sh: line 1: syntax error near unexpected token newline' /mnt/dietpi_userdata/downloads/mov-2-mp4.sh: line 1: '

I'm not sure exactly where the script is hanging but I believe its in the following function

Update folders

echo "Updating Folders"
for i in "${folders_to_update[@]}"
do
echo "Processing ${i}"
:
php $installation_path/occ files:scan --path="$i"
done
echo "Done Updating"

I had to kill the running script. In addition I re-ran the php occ files:scan directive manually I really just ran it like the following
php -u www occ files:scan --all

Anyway I looked at the converted mp4 files after the conversion. Many were great. About 20% of the converted files wouldn't open. I have no idea what the issue was. A few of them played for about 5 seconds and then stopped where as the original .mov file played for about 1 minute. Not sure if you could help.