Bash script not echoing after executing jar file - bash

Question

I recently made a bash script which automatically creates a Minecraft server using the server.jar file. I told it to echo a string which is a command in Minecraft after a certain delay, in order to have it be echoed after the server is done loading. For some reason, after finishing loading the Minecraft world, it just doesn't echo that string.
Here's the script:
#!/bin/bash
mkdir minecraft_server
cd minecraft_server
wget https://launcher.mojang.com/v1/objects/e00c4052dac1d59a1188b2aa9d5a87113aaf1122/server.jar
java -Xmx5G -Xms3G -jar server.jar nogui
sed -i "s/^eula.*/eula=true/" /home/my name/minecraft_server/eula.txt
sed -i "s/^server-port.*/server-port=40004/" /home/my name/minecraft_server/server.properties
java -Xmx5G -Xms3G -jar server.jar nogui
sleep 60
echo "/op My Username"

Answer 1

There are many ready-made minecraft server launch script, which also feature screen for remote management. Although if you want to go a bit further by yourself, here is a cleaned-up version of your script. It works but does not include the op command. This need to be dealt with separately.
#!/bin/sh
server_dl_url='https://launcher.mojang.com/v1/objects/e00c4052dac1d59a1188b2aa9d5a87113aaf1122/server.jar'
server_dir='./minecraft_server'
server_jar='server.jar'
if mkdir -p "${server_dir}" && cd "${server_dir}"; then
# If server.jar does not exist, download it
if ! [ -e "${server_jar}" ]; then
if ! wget --output-document="${server_jar}" "${server_dl_url}"; then
printf "Could not dowload %s from %s\\n" \
"${server_jar}" "${server_dl_url}"
exit 1
fi >&2
fi
# Check if it has eula.txt, if not, generate it with --initSettings
if ! [ -e 'eula.txt' ]; then
# Initializes 'server.properties' and 'eula.txt', then quits
if ! java -jar "${server_jar}" --initSettings --nogui; then
printf "Could not initialize 'server.properties' and 'eula.txt'\\n"
exit 1
fi >&2
fi
if ! grep -q '^eula=true' 'eula.txt'; then
sed -i.bak 's/^eula=.*/eula=true/' 'eula.txt'
fi
# Run the actual server
java -Xmx5G -Xms3G -jar server.jar nogui &
fi