diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 73b7e74..e7a6e64 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ on:
 # A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
   # This workflow contains a single job called "build"
-  build:
+  test:
     # The type of runner that the job will run on
     runs-on: ubuntu-latest
 
@@ -23,8 +23,8 @@ jobs:
         with:
           submodules: 'recursive'
 
-      - name: Install kcov
-        run: sudo apt-get install -y kcov
+      - name: Install kcov and shellcheck
+        run: sudo apt-get install -y kcov shellcheck
 
       - name: Run tests
         run: test/test.sh
@@ -37,4 +37,7 @@ jobs:
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           file: ./coverage/test.sh/cov.xml
+
+      - name: shellcheck
+        run: shellcheck backup.sh
         
diff --git a/README.md b/README.md
index e3cf5d3..208d3e2 100644
--- a/README.md
+++ b/README.md
@@ -1,28 +1,40 @@
 # Minecraft Backup
-Backup script for Linux servers running a Minecraft server in a GNU Screen or tmux
+![GitHub Workflow Status](https://img.shields.io/github/workflow/status/nicolaschan/minecraft-backup/CI)
+[![codecov](https://codecov.io/gh/nicolaschan/minecraft-backup/branch/master/graph/badge.svg?token=LCbVC4TbYJ)](https://codecov.io/gh/nicolaschan/minecraft-backup)
 
-### Disclaimer
-Backups are essential to the integrity of your Minecraft world. You should automate regular backups and **check that your backups work**. While this script has been used in production for several years, it is up to you to make sure that your backups work and that you have a reliable backup policy. 
-
-Please refer to the LICENSE (MIT License) for the full legal disclaimer.
+Backup script for Minecraft servers on Linux. 
+Supports servers running in [screen](https://en.wikipedia.org/wiki/GNU_Screen), [tmux](https://en.wikipedia.org/wiki/Tmux), or with [RCON](https://wiki.vg/RCON) enabled.
 
 ## Features
 - Create backups of your world folder
 - Manage deletion of old backups
-  - "thin" - keep last 24 hourly, last 30 daily, and use remaining space for monthly backups
+  - "thin" - keep last 24 hourly, last 30 daily, and use remaining space for weekly backups
   - "sequential" - delete oldest backup
-- Choose your own compression algorithm (tested with: `gzip`, `xz`, `zstd`)
-- Able to print backup status and info to the Minecraft chat
+- Works on vanilla (no plugins required)
+- Print backup status to the Minecraft chat
 
-## Requirements
-- Linux computer (tested on Ubuntu)
-- GNU Screen (running your Minecraft server)
-- Minecraft server (tested with Vanilla 1.10.2 only)
+## Install
+```bash
+wget https://raw.githubusercontent.com/nicolaschan/minecraft-backup/master/backup.sh
+chmod +x backup.sh
+```
 
-## Installation
-1. Download the script: `$ wget https://raw.githubusercontent.com/nicolaschan/minecraft-backup/master/backup.sh`
-2. Mark as executable: `$ chmod +x backup.sh`
-3. Use the command line options or configure default values at the top of `backup.sh`:
+Make sure your system has `tar` and your chosen compression algorithm (`gzip` by default) installed.
+If using RCON, you will also need to have the [`xxd`](https://linux.die.net/man/1/xxd) command.
+
+## Usage
+```bash
+# If connecting with RCON:
+./backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s localhost:25575:secret -w rcon
+
+# If running on screen called "minecraft":
+./backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s minecraft
+
+# If running on tmux session 0:
+./backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s 0 -w tmux 
+```
+
+This will show chat messages (`-c`) and save a backup of `/home/user/server/world` into `/mnt/storage/backups` using the default thinning deletion policy for old backups.
 
 Command line options:
 ```text
@@ -38,21 +50,18 @@ Command line options:
 -o    Output directory
 -p    Prefix that shows in Minecraft chat (default: Backup)
 -q    Suppress warnings
--s    Minecraft server screen name
+-s    Screen name, tmux session name, or hostname:port:password for RCON
 -v    Verbose mode
--w    Window manager: screen (default) or tmux
+-w    Window manager: screen (default), tmux, RCON 
 ```
 
-Example usage of command line options:
-```bash
-./backup.sh -c -i /home/server/minecraft-server/world -o /mnt/external-storage/minecraft-backups -s minecraft
+### Automate backups with cron
+- Edit the crontab with `crontab -e`
+- Example for hourly backups:
+```
+00 * * * * /path/to/backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s minecraft
 ```
-This will use show chat messages (`-c`) in the screen called "minecraft" and save a backup of `/home/server/minecraft-server/world` into `/mnt/external-storage/minecraft-backups` using the default thinning delete policy for old backups.
 
-4. Create a cron job to automatically backup:
-    - Edit the crontab: `$ crontab -e`
-    - Example for hourly backups: `00 * * * * /path/to/backup.sh`
-  
 ## Retrieving Backups
 Always test your backups! Backups are in the `tar` format and compressed depending on the option you choose. To restore, first decompress if necessary and then extract using tar. You may be able to do this in one command if `tar` supports your compression option, as is the case with `gzip`:
 
@@ -65,11 +74,30 @@ tar -xzvf /path/to/backups/2019-04-09_02-15-01.tar.gz
 
 Then you can move your restored world (`restored-world` in this case) to your Minecraft server folder and rename it (usually called `world`) so the Minecraft server uses it.
 
+## Why not use `tar` directly?
+If you use `tar` while the server is running, you will likely get an error like this because Minecraft autosaves the world periodically:
+```
+tar: /some/path/here/world/region/r.1.11.mca: file changed as we read it
+```
+To fix this problem, the backup script disables autosaving with the `save-off` Minecraft command before running `tar` and then re-enables autosaving after `tar` is done. 
+
 ## Help
 - Make sure the compression algorithm you specify is installed on your system. (zstd is not installed by default)
 - Make sure your compression algorithm is in the crontab's PATH
 - Make sure cron has permissions for all the files involved and access to the Minecraft server's GNU Screen
 - It's surprising how much space backups can take--make sure you have enough empty space
-- `SERVER_DIRECTORY` should be the server directory, not the `world` directory
 - Do not put trailing `/` in the `SERVER_DIRECTORY` or `BACKUP_DIRECTORY`
 - If "thin" delete method is behaving weirdly, try emptying your backup directory or switch to "sequential"
+
+## Known Issues
+There is a Minecraft bug [MC-217729](https://bugs.mojang.com/projects/MC/issues/MC-217729) in recent Minecraft server versions that cause them to automatically save the world even after receiving the `save-off` command. Until this is fixed, there is a chance that the backup will fail because the world files are modified by Minecraft in the process of creating the backup. This script will try to detect and report this problem if it does occur.
+
+## Disclaimer
+Backups are essential to the integrity of your Minecraft world. You should automate regular backups and **check that your backups work**. It is up to you to make sure that your backups work and that you have a reliable backup policy. 
+
+Some backup tips:
+- Drives get corrupted or fail! Backup to a _different_ drive than the one your server is running on, so if your main drive fails then you have backups.
+- _Automate_ backups so you never lose too much progress.
+- Check that your backups work from time to time.
+
+Please refer to the LICENSE (MIT License) for the full legal disclaimer.
diff --git a/backup.sh b/backup.sh
index 9f2ad43..4100f73 100755
--- a/backup.sh
+++ b/backup.sh
@@ -8,7 +8,7 @@
 # For most convenience, run automatically with cron.
 
 # Default Configuration 
-SCREEN_NAME="" # Name of the GNU Screen or tmux pane your Minecraft server is running in
+SCREEN_NAME="" # Name of the GNU Screen, tmux session, or hostname:port:password for RCON
 SERVER_WORLD="" # Server world directory
 BACKUP_DIRECTORY="" # Directory to save backups in
 MAX_BACKUPS=128 # -1 indicates unlimited
@@ -20,12 +20,24 @@ ENABLE_CHAT_MESSAGES=false # Tell players in Minecraft chat about backup status
 PREFIX="Backup" # Shows in the chat message
 DEBUG=false # Enable debug messages
 SUPPRESS_WARNINGS=false # Suppress warnings
-WINDOW_MANAGER="screen" # Choices: screen, tmux
+WINDOW_MANAGER="screen" # Choices: screen, tmux, RCON
 
 # Other Variables (do not modify)
 DATE_FORMAT="%F_%H-%M-%S"
 TIMESTAMP=$(date +$DATE_FORMAT)
 
+log-fatal () {
+  echo -e "\033[0;31mFATAL:\033[0m $*"
+}
+log-warning () {
+  echo -e "\033[0;33mWARNING:\033[0m $*"
+}
+debug-log () {
+  if "$DEBUG"; then
+    echo "$1"
+  fi
+}
+
 while getopts 'a:cd:e:f:hi:l:m:o:p:qs:vw:' FLAG; do
   case $FLAG in
     a) COMPRESSION_ALGORITHM=$OPTARG ;;
@@ -47,9 +59,9 @@ while getopts 'a:cd:e:f:hi:l:m:o:p:qs:vw:' FLAG; do
        echo "-o    Output directory"
        echo "-p    Prefix that shows in Minecraft chat (default: Backup)"
        echo "-q    Suppress warnings"
-       echo "-s    Minecraft server screen name"
+       echo "-s    Screen name, tmux session name, or hostname:port:password for RCON"
        echo "-v    Verbose mode"
-       echo "-w    Window manager: screen (default) or tmux"
+       echo "-w    Window manager: screen (default), tmux, RCON"
        exit 0
        ;;
     i) SERVER_WORLD=$OPTARG ;;
@@ -61,14 +73,118 @@ while getopts 'a:cd:e:f:hi:l:m:o:p:qs:vw:' FLAG; do
     s) SCREEN_NAME=$OPTARG ;;
     v) DEBUG=true ;;
     w) WINDOW_MANAGER=$OPTARG ;;
+    *) log-fatal "Invalid option -$FLAG"; exit 1 ;;
   esac
 done
 
-log-fatal () {
-  echo -e "\033[0;31mFATAL:\033[0m $*"
-}
-log-warning () {
-  echo -e "\033[0;33mWARNING:\033[0m $*"
+rcon-command () {
+  HOST="$(echo "$1" | cut -d: -f1)"
+  PORT="$(echo "$1" | cut -d: -f2)"
+  PASSWORD="$(echo "$1" | cut -d: -f3-)"
+  COMMAND="$2"
+
+  reverse-hex-endian () {
+    # Given a 4-byte hex integer, reverse endianness
+    while read -r -d '' -N 8 INTEGER; do
+      echo "$INTEGER" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/'
+    done
+  }
+
+  decode-hex-int () {
+    # decode little-endian hex integer
+    while read -r -d '' -N 8 INTEGER; do
+      BIG_ENDIAN_HEX=$(echo "$INTEGER" | reverse-hex-endian)
+      echo "$((16#$BIG_ENDIAN_HEX))"
+    done
+  }
+
+  stream-to-hex () {
+    xxd -ps
+  }
+
+  hex-to-stream () {
+    xxd -ps -r
+  }
+
+  encode-int () {
+    # Encode an integer as 4 bytes in little endian and return as hex
+    INT="$1"
+    # Source: https://stackoverflow.com/a/9955198
+    printf "%08x" "$INT" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/' 
+  }
+
+  encode () {
+    # Encode a packet type and payload for the rcon protocol
+    TYPE="$1"
+    PAYLOAD="$2"
+    REQUEST_ID="$3"
+    PAYLOAD_LENGTH="${#PAYLOAD}" 
+    TOTAL_LENGTH="$((4 + 4 + PAYLOAD_LENGTH + 1 + 1))"
+
+    OUTPUT=""
+    OUTPUT+=$(encode-int "$TOTAL_LENGTH")
+    OUTPUT+=$(encode-int "$REQUEST_ID")
+    OUTPUT+=$(encode-int "$TYPE")
+    OUTPUT+=$(echo -n "$PAYLOAD" | stream-to-hex)
+    OUTPUT+="0000"
+    
+    echo -n "$OUTPUT" | hex-to-stream 
+  }
+
+  read-response () {
+    # read next response packet and return the payload text
+    HEX_LENGTH=$(head -c4 <&3 | stream-to-hex | reverse-hex-endian)
+    LENGTH=$((16#$HEX_LENGTH))
+
+    RESPONSE_PAYLOAD=$(head -c $LENGTH <&3 | stream-to-hex)
+    echo -n "$RESPONSE_PAYLOAD"
+  }
+
+  response-request-id () {
+    echo -n "${1:0:8}" | decode-hex-int
+  }
+
+  response-type () {
+    echo -n "${1:8:8}" | decode-hex-int
+  }
+
+  response-payload () {
+    echo -n "${1:16:-4}" | hex-to-stream
+  }
+
+  login () {
+    PASSWORD="$1"
+    encode 3 "$PASSWORD" 12 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+
+    RESPONSE_REQUEST_ID=$(response-request-id "$RESPONSE")
+    if [ "$RESPONSE_REQUEST_ID" -eq -1 ] || [ "$RESPONSE_REQUEST_ID" -eq 4294967295 ]; then
+      log-warning "RCON connection failed: Wrong RCON password" 1>&2
+      return 1
+    fi
+  }
+
+  run-command () {
+    COMMAND="$1"
+    
+    # encode 2 "$COMMAND" 13 >> "$OUT_PIPE"
+    encode 2 "$COMMAND" 13 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+    response-payload "$RESPONSE"
+  }
+
+  # Open a TCP socket
+  # Source: https://www.xmodulo.com/tcp-udp-socket-bash-shell.html
+  exec 3<>/dev/tcp/"$HOST"/"$PORT"
+
+  login "$PASSWORD" || return 1
+  debug-log "$(run-command "$COMMAND")"
+
+  # Close the socket
+  exec 3<&-
+  exec 3>&-
 }
 
 if [[ $COMPRESSION_FILE_EXTENSION == "." ]]; then
@@ -78,7 +194,7 @@ fi
 # Check for missing encouraged arguments
 if ! $SUPPRESS_WARNINGS; then
   if [[ $SCREEN_NAME == "" ]]; then
-    log-warning "Minecraft screen name not specified (use -s)"
+    log-warning "Minecraft screen/tmux/rcon location not specified (use -s)"
   fi
 fi
 # Check for required arguments
@@ -96,8 +212,8 @@ if $MISSING_CONFIGURATION; then
   exit 1
 fi
 
-ARCHIVE_FILE_NAME=$TIMESTAMP.tar$COMPRESSION_FILE_EXTENSION
-ARCHIVE_PATH=$BACKUP_DIRECTORY/$ARCHIVE_FILE_NAME
+ARCHIVE_FILE_NAME="$TIMESTAMP.tar$COMPRESSION_FILE_EXTENSION"
+ARCHIVE_PATH="$BACKUP_DIRECTORY/$ARCHIVE_FILE_NAME"
 
 # Minecraft server screen interface functions
 message-players () {
@@ -109,9 +225,11 @@ execute-command () {
   local COMMAND=$1
   if [[ $SCREEN_NAME != "" ]]; then
     case $WINDOW_MANAGER in
-      "screen") screen -S $SCREEN_NAME -p 0 -X stuff "$COMMAND$(printf \\r)"
+      "screen") screen -S "$SCREEN_NAME" -p 0 -X stuff "$COMMAND$(printf \\r)"
         ;;
-      "tmux") tmux send-keys -t $SCREEN_NAME "$COMMAND" ENTER
+      "tmux") tmux send-keys -t "$SCREEN_NAME" "$COMMAND" ENTER
+        ;;
+      "RCON"|"rcon") rcon-command "$SCREEN_NAME" "$COMMAND"
         ;;
     esac
   fi
@@ -130,9 +248,7 @@ message-players-color () {
   local MESSAGE=$1
   local HOVER_MESSAGE=$2
   local COLOR=$3
-  if $DEBUG; then
-    echo "$MESSAGE ($HOVER_MESSAGE)"
-  fi
+  debug-log "$MESSAGE ($HOVER_MESSAGE)"
   if $ENABLE_CHAT_MESSAGES; then
     execute-command "tellraw @a [\"\",{\"text\":\"[$PREFIX] \",\"color\":\"gray\",\"italic\":true},{\"text\":\"$MESSAGE\",\"color\":\"$COLOR\",\"italic\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":{\"text\":\"\",\"extra\":[{\"text\":\"$HOVER_MESSAGE\"}]}}}]"
   fi
@@ -143,50 +259,67 @@ message-players "Starting backup..." "$ARCHIVE_FILE_NAME"
 
 # Parse file timestamp to one readable by "date" 
 parse-file-timestamp () {
-  local DATE_STRING=$(echo $1 | awk -F_ '{gsub(/-/,":",$2); print $1" "$2}')
-  echo $DATE_STRING
+  local DATE_STRING
+  DATE_STRING="$(echo "$1" | awk -F_ '{gsub(/-/,":",$2); print $1" "$2}')"
+  echo "$DATE_STRING"
 }
 
 # Delete a backup
 delete-backup () {
   local BACKUP=$1
-  rm $BACKUP_DIRECTORY/$BACKUP
+  rm "$BACKUP_DIRECTORY"/"$BACKUP"
   message-players "Deleted old backup" "$BACKUP"
 }
 
 # Sequential delete method
 delete-sequentially () {
-  local BACKUPS=($(ls $BACKUP_DIRECTORY))
+  local BACKUPS=("$BACKUP_DIRECTORY"/*)
   while [[ $MAX_BACKUPS -ge 0 && ${#BACKUPS[@]} -gt $MAX_BACKUPS ]]; do
-    delete-backup ${BACKUPS[0]}
-    BACKUPS=($(ls $BACKUP_DIRECTORY))
+    delete-backup "$(basename "${BACKUPS[0]}")"
+    BACKUPS=("$BACKUP_DIRECTORY"/*)
   done
 }
 
 # Functions to sort backups into correct categories based on timestamps
 is-hourly-backup () {
   local TIMESTAMP=$*
-  local MINUTE=$(date -d "$TIMESTAMP" +%M)
-  return $MINUTE
+  local MINUTE
+  MINUTE=$(date -d "$TIMESTAMP" +%M)
+  return "$MINUTE"
 }
 is-daily-backup () {
   local TIMESTAMP=$*
-  local HOUR=$(date -d "$TIMESTAMP" +%H)
-  return $HOUR
+  local HOUR
+  HOUR=$(date -d "$TIMESTAMP" +%H)
+  return "$HOUR"
 }
 is-weekly-backup () {
   local TIMESTAMP=$*
-  local DAY=$(date -d "$TIMESTAMP" +%u)
-  return $((DAY - 1))
+  local DAY
+  DAY=$(date -d "$TIMESTAMP" +%u)
+  return "$((DAY - 1))"
 }
 
 # Helper function to sum an array
 array-sum () {
   SUM=0
-  for NUMBER in $*; do
+  for NUMBER in "$@"; do
     (( SUM += NUMBER ))
   done
-  echo $SUM
+  echo "$SUM"
+}
+
+# Given two exit codes, print a nonzero one if there is one
+exit-code () {
+  if [ "$1" -ne 0 ]; then
+    echo "$1"
+  else
+    if [[ "$2" == "" ]]; then
+      echo 0
+    else
+      echo "$2"
+    fi
+  fi
 }
 
 # Thinning delete method
@@ -198,7 +331,7 @@ delete-thinning () {
   local BLOCK_FUNCTIONS=("is-hourly-backup" "is-daily-backup" "is-weekly-backup")
 
   # Warn if $MAX_BACKUPS does not have enough room for all the blocks
-  TOTAL_BLOCK_SIZE=$(array-sum ${BLOCK_SIZES[@]})
+  TOTAL_BLOCK_SIZE=$(array-sum "${BLOCK_SIZES[@]}")
   if [[  $MAX_BACKUPS != -1 ]] && [[ $TOTAL_BLOCK_SIZE -gt $MAX_BACKUPS ]]; then
     if ! $SUPPRESS_WARNINGS; then
       log-warning "MAX_BACKUPS ($MAX_BACKUPS) is smaller than TOTAL_BLOCK_SIZE ($TOTAL_BLOCK_SIZE)"
@@ -206,29 +339,29 @@ delete-thinning () {
   fi
 
   local CURRENT_INDEX=0
-  local BACKUPS=($(ls -r $BACKUP_DIRECTORY)) # List newest first
+  local BACKUPS=("$BACKUP_DIRECTORY"/*) # List newest first
 
-  for BLOCK_INDEX in ${!BLOCK_SIZES[@]}; do
+  for BLOCK_INDEX in "${!BLOCK_SIZES[@]}"; do
     local BLOCK_SIZE=${BLOCK_SIZES[BLOCK_INDEX]}
     local BLOCK_FUNCTION=${BLOCK_FUNCTIONS[BLOCK_INDEX]}
     local OLDEST_BACKUP_IN_BLOCK_INDEX=$((BLOCK_SIZE + CURRENT_INDEX)) # Not an off-by-one error because a new backup was already saved 
-    local OLDEST_BACKUP_IN_BLOCK=${BACKUPS[OLDEST_BACKUP_IN_BLOCK_INDEX]}
+    local OLDEST_BACKUP_IN_BLOCK
+    OLDEST_BACKUP_IN_BLOCK="$(basename "${BACKUPS[OLDEST_BACKUP_IN_BLOCK_INDEX]}")"
 
-    if [[ $OLDEST_BACKUP_IN_BLOCK == "" ]]; then
+    if [[ "$OLDEST_BACKUP_IN_BLOCK" == "" ]]; then
       break
     fi
 
-    local OLDEST_BACKUP_TIMESTAMP=$(parse-file-timestamp ${OLDEST_BACKUP_IN_BLOCK:0:19})
+    local OLDEST_BACKUP_TIMESTAMP
+    OLDEST_BACKUP_TIMESTAMP=$(parse-file-timestamp "${OLDEST_BACKUP_IN_BLOCK:0:19}")
     local BLOCK_COMMAND="$BLOCK_FUNCTION $OLDEST_BACKUP_TIMESTAMP"
 
     if $BLOCK_COMMAND; then
       # Oldest backup in this block satisfies the condition for placement in the next block
-      if $DEBUG; then
-        echo "$OLDEST_BACKUP_IN_BLOCK promoted to next block" 
-      fi
+      debug-log "$OLDEST_BACKUP_IN_BLOCK promoted to next block" 
     else
       # Oldest backup in this block does not satisfy the condition for placement in next block
-      delete-backup $OLDEST_BACKUP_IN_BLOCK
+      delete-backup "$OLDEST_BACKUP_IN_BLOCK"
       break
     fi
 
@@ -238,6 +371,9 @@ delete-thinning () {
   delete-sequentially
 }
 
+# Ensure backup directory exists
+mkdir -p "$(dirname "$ARCHIVE_PATH")"
+
 # Disable world autosaving
 execute-command "save-off"
 
@@ -245,12 +381,16 @@ execute-command "save-off"
 START_TIME=$(date +"%s")
 case $COMPRESSION_ALGORITHM in
   # No compression
-  "") tar -cf $ARCHIVE_PATH -C $SERVER_WORLD . 
+  "") tar -cf "$ARCHIVE_PATH" -C "$SERVER_WORLD" .
     ;;
   # With compression
-  *) tar -cf - -C $SERVER_WORLD . | $COMPRESSION_ALGORITHM -cv -$COMPRESSION_LEVEL - > $ARCHIVE_PATH 2>> /dev/null
+  *) tar -cf - -C "$SERVER_WORLD" . | $COMPRESSION_ALGORITHM -cv -"$COMPRESSION_LEVEL" - > "$ARCHIVE_PATH" 2>> /dev/null
     ;;
 esac
+ARCHIVE_EXIT_CODE="$(exit-code "${PIPESTATUS[0]}" "${PIPESTATUS[1]}")"
+if [ "$ARCHIVE_EXIT_CODE" -ne 0 ]; then
+  log-fatal "Archive command exited with nonzero exit code $ARCHIVE_EXIT_CODE"
+fi
 sync
 END_TIME=$(date +"%s")
 
@@ -271,17 +411,22 @@ delete-old-backups () {
 }
 
 # Notify players of completion
-WORLD_SIZE_BYTES=$(du -b --max-depth=0 $SERVER_WORLD | awk '{print $1}')
-ARCHIVE_SIZE_BYTES=$(du -b $ARCHIVE_PATH | awk '{print $1}')
-ARCHIVE_SIZE=$(du -h $ARCHIVE_PATH | awk '{print $1}')
-BACKUP_DIRECTORY_SIZE=$(du -h --max-depth=0 $BACKUP_DIRECTORY | awk '{print $1}')
+WORLD_SIZE_BYTES=$(du -b --max-depth=0 "$SERVER_WORLD" | awk '{print $1}')
+ARCHIVE_SIZE_BYTES=$(du -b "$ARCHIVE_PATH" | awk '{print $1}')
+ARCHIVE_SIZE=$(du -h "$ARCHIVE_PATH" | awk '{print $1}')
+BACKUP_DIRECTORY_SIZE=$(du -h --max-depth=0 "$BACKUP_DIRECTORY" | awk '{print $1}')
 TIME_DELTA=$((END_TIME - START_TIME))
 
 # Check that archive size is not null and at least 200 Bytes
-if [[ "$WORLD_SIZE_BYTES" -gt 0 && "$ARCHIVE_SIZE" != "" && "$ARCHIVE_SIZE_BYTES" -gt 200 ]]; then
-  COMPRESSION_PERCENT=$(($ARCHIVE_SIZE_BYTES * 100 / $WORLD_SIZE_BYTES))
+if [[ "$ARCHIVE_EXIT_CODE" -eq 0 && "$WORLD_SIZE_BYTES" -gt 0 && "$ARCHIVE_SIZE" != "" && "$ARCHIVE_SIZE_BYTES" -gt 200 ]]; then
+  COMPRESSION_PERCENT=$((ARCHIVE_SIZE_BYTES * 100 / WORLD_SIZE_BYTES))
   message-players-success "Backup complete!" "$TIME_DELTA s, $ARCHIVE_SIZE/$BACKUP_DIRECTORY_SIZE, $COMPRESSION_PERCENT%"
   delete-old-backups
 else
   message-players-error "Backup was not saved!" "Please notify an administrator"
+  if [ "$ARCHIVE_EXIT_CODE" -ne 0 ]; then
+    exit "$ARCHIVE_EXIT_CODE"
+  else
+    exit 1
+  fi
 fi
diff --git a/rcon.sh b/rcon.sh
new file mode 100755
index 0000000..9bf8e58
--- /dev/null
+++ b/rcon.sh
@@ -0,0 +1,119 @@
+#!/usr/bin/env bash
+
+rcon-command () {
+  HOST="$(echo "$1" | cut -d: -f1)"
+  PORT="$(echo "$1" | cut -d: -f2)"
+  PASSWORD="$(echo "$1" | cut -d: -f3-)"
+  COMMAND="$2"
+
+  reverse-hex-endian () {
+    # Given a 4-byte hex integer, reverse endianness
+    while read -r -d '' -N 8 INTEGER; do
+      echo "$INTEGER" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/'
+    done
+  }
+
+  decode-hex-int () {
+    # decode little-endian hex integer
+    while read -r -d '' -N 8 INTEGER; do
+      BIG_ENDIAN_HEX=$(echo "$INTEGER" | reverse-hex-endian)
+      echo "$((16#$BIG_ENDIAN_HEX))"
+    done
+  }
+
+  stream-to-hex () {
+    xxd -ps
+  }
+
+  hex-to-stream () {
+    xxd -ps -r
+  }
+
+  encode-int () {
+    # Encode an integer as 4 bytes in little endian and return as hex
+    INT="$1"
+    # Source: https://stackoverflow.com/a/9955198
+    printf "%08x" "$INT" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/' 
+  }
+
+  encode () {
+    # Encode a packet type and payload for the rcon protocol
+    TYPE="$1"
+    PAYLOAD="$2"
+    REQUEST_ID="$3"
+    PAYLOAD_LENGTH="${#PAYLOAD}" 
+    TOTAL_LENGTH="$((4 + 4 + PAYLOAD_LENGTH + 1 + 1))"
+
+    OUTPUT=""
+    OUTPUT+=$(encode-int "$TOTAL_LENGTH")
+    OUTPUT+=$(encode-int "$REQUEST_ID")
+    OUTPUT+=$(encode-int "$TYPE")
+    OUTPUT+=$(echo -n "$PAYLOAD" | stream-to-hex)
+    OUTPUT+="0000"
+    
+    echo -n "$OUTPUT" | hex-to-stream 
+  }
+
+  read-response () {
+    # read next response packet and return the payload text
+    HEX_LENGTH=$(head -c4 <&3 | stream-to-hex | reverse-hex-endian)
+    LENGTH=$((16#$HEX_LENGTH))
+
+    RESPONSE_PAYLOAD=$(head -c $LENGTH <&3 | stream-to-hex)
+    echo -n "$RESPONSE_PAYLOAD"
+  }
+
+  response-request-id () {
+    echo -n "${1:0:8}" | decode-hex-int
+  }
+
+  response-type () {
+    echo -n "${1:8:8}" | decode-hex-int
+  }
+
+  response-payload () {
+    echo -n "${1:16:-4}" | hex-to-stream
+  }
+
+  login () {
+    PASSWORD="$1"
+    encode 3 "$PASSWORD" 12 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+
+    RESPONSE_REQUEST_ID=$(response-request-id "$RESPONSE")
+    if [ "$RESPONSE_REQUEST_ID" -eq -1 ] || [ "$RESPONSE_REQUEST_ID" -eq 4294967295 ]; then
+      echo "Authentication failed: Wrong RCON password" 1>&2
+      return 1
+    fi
+  }
+
+  run-command () {
+    COMMAND="$1"
+    
+    # encode 2 "$COMMAND" 13 >> "$OUT_PIPE"
+    encode 2 "$COMMAND" 13 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+    response-payload "$RESPONSE"
+  }
+
+  # Open a TCP socket
+  # Source: https://www.xmodulo.com/tcp-udp-socket-bash-shell.html
+  exec 3<>/dev/tcp/"$HOST"/"$PORT"
+
+  login "$PASSWORD" || return 1
+  run-command "$COMMAND"
+
+  # Close the socket
+  exec 3<&-
+  exec 3>&-
+}
+
+
+HOST="$1"
+PORT="$2"
+PASSWORD="$3"
+COMMAND="$4"
+
+rcon-command "$HOST:$PORT:$PASSWORD" "$COMMAND"
diff --git a/test/mock_rcon.py b/test/mock_rcon.py
new file mode 100644
index 0000000..c5f7c35
--- /dev/null
+++ b/test/mock_rcon.py
@@ -0,0 +1,31 @@
+# Reference: https://docs.python.org/3/library/socketserver.html
+import codecs
+import socketserver
+import sys
+
+class Handler(socketserver.BaseRequestHandler):
+    def handle(self):
+        while True:
+            length = int.from_bytes(self.request.recv(4), 'little')
+            if not length:
+                continue
+
+            self.request.recv(4)
+            type_ = int.from_bytes(self.request.recv(4), 'little')
+            self.data = self.request.recv(length - 8)[:-2].decode('utf-8')
+            if self.data:
+                if type_ == 2:
+                    print(self.data)
+                    sys.stdout.flush()
+            try:
+                if type_ == 3 and self.data != sys.argv[2]:
+                    self.request.sendall(codecs.decode('0a000000ffffffff020000000000', 'hex'))
+                else:
+                    self.request.sendall(codecs.decode('0a00000010000000020000000000', 'hex'))
+            except:
+                break
+
+if __name__ == "__main__":
+    HOST, PORT = "localhost", int(sys.argv[1])
+    with socketserver.ThreadingTCPServer((HOST, PORT), Handler) as server:
+        server.serve_forever()
diff --git a/test/test.sh b/test/test.sh
index 7e3e0c9..7b35b4f 100755
--- a/test/test.sh
+++ b/test/test.sh
@@ -5,6 +5,8 @@
 TEST_DIR="test"
 TEST_TMP="$TEST_DIR/tmp"
 SCREEN_TMP="tmp-screen"
+RCON_PORT="8088"
+RCON_PASSWORD="supersecret"
 setUp () {
   rm -rf "$TEST_TMP"
   mkdir -p "$TEST_TMP/server/world"
@@ -17,10 +19,17 @@ setUp () {
   screen -S "$SCREEN_TMP" -X stuff "cat > $TEST_TMP/screen-output\n"
   tmux new-session -d -s "$SCREEN_TMP"
   tmux send-keys -t "$SCREEN_TMP" "cat > $TEST_TMP/tmux-output" ENTER
-  sleep 0.5
+  python test/mock_rcon.py "$RCON_PORT" "$RCON_PASSWORD" > "$TEST_TMP/rcon-output" &
+  echo "$!" > "$TEST_TMP/rcon-pid"
+
+  while ! [[ (-f "$TEST_TMP/screen-output")  && (-f "$TEST_TMP/tmux-output") && (-f "$TEST_TMP/rcon-output") ]]; do
+    sleep 0.1
+  done
 }
 
 tearDown () {
+  RCON_PID="$(cat "$TEST_TMP/rcon-pid")"
+  kill "$RCON_PID" >/dev/null 2>&1 || true
   screen -S "$SCREEN_TMP" -X quit >/dev/null 2>&1 || true
   tmux kill-session -t "$SCREEN_TMP" >/dev/null 2>&1 || true
 }
@@ -35,12 +44,18 @@ assert-equals-directory () {
   fi
 }
 
+check-backup-full-paths () {
+  BACKUP_ARCHIVE="$1"
+  WORLD_DIR="$2"
+  mkdir -p "$TEST_TMP/restored"
+  tar --extract --file "$BACKUP_ARCHIVE" --directory "$TEST_TMP/restored"
+  assert-equals-directory "$WORLD_DIR" "$TEST_TMP/restored"
+  rm -rf "$TEST_TMP/restored"
+}
+
 check-backup () {
   BACKUP_ARCHIVE="$1"
-  mkdir -p "$TEST_TMP/restored"
-  tar --extract --file "$TEST_TMP/backups/$BACKUP_ARCHIVE" --directory "$TEST_TMP/restored"
-  assert-equals-directory "$TEST_TMP/server/world" "$TEST_TMP/restored"
-  rm -rf "$TEST_TMP/restored"
+  check-backup-full-paths "$TEST_TMP/backups/$BACKUP_ARCHIVE" "$TEST_TMP/server/world"
 }
 
 # Tests
@@ -51,6 +66,17 @@ test-backup-defaults () {
   check-backup "$TIMESTAMP.tar.gz"
 }
 
+test-backup-spaces-in-directory () {
+  TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
+  WORLD_SPACES="$TEST_TMP/minecraft server/the world"
+  mkdir -p "$(dirname "$WORLD_SPACES")"
+  BACKUP_SPACES="$TEST_TMP/My Backups"
+  mkdir -p "$BACKUP_SPACES"
+  cp -r "$TEST_TMP/server/world" "$WORLD_SPACES"
+  ./backup.sh -i "$WORLD_SPACES" -o "$BACKUP_SPACES" -s "$SCREEN_TMP" -f "$TIMESTAMP"
+  check-backup-full-paths "$BACKUP_SPACES/$TIMESTAMP.tar.gz" "$WORLD_SPACES"
+}
+
 test-backup-no-compression () {
   TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
   ./backup.sh -a "" -e "" -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "$SCREEN_TMP" -f "$TIMESTAMP"
@@ -88,7 +114,7 @@ test-missing-options () {
   OUTPUT="$(./backup.sh 2>&1)"
   EXIT_CODE="$?"
   assertEquals 1 "$EXIT_CODE"
-  assertContains "$OUTPUT" "Minecraft screen name not specified"
+  assertContains "$OUTPUT" "Minecraft screen/tmux/rcon location not specified (use -s)"
   assertContains "$OUTPUT" "Server world not specified"
   assertContains "$OUTPUT" "Backup directory not specified"
 }
@@ -97,7 +123,14 @@ test-missing-options-suppress-warnings () {
   OUTPUT="$(./backup.sh -q 2>&1)"
   EXIT_CODE="$?"
   assertEquals 1 "$EXIT_CODE"
-  assertNotContains "$OUTPUT" "Minecraft screen name not specified"
+  assertNotContains "$OUTPUT" "Minecraft screen/tmux/rcon location not specified (use -s)"
+}
+
+test-invalid-options () {
+  OUTPUT="$(./backup.sh -z 2>&1)"
+  EXIT_CODE="$?"
+  assertEquals 1 "$EXIT_CODE"
+  assertContains "$OUTPUT" "Invalid option"
 }
 
 test-empty-world-warning () {
@@ -113,6 +146,14 @@ test-block-size-warning () {
   assertContains "$OUTPUT" "is smaller than TOTAL_BLOCK_SIZE"
 }
 
+test-nonzero-exit-warning () {
+  TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
+  OUTPUT="$(./backup.sh -a _BLAH_ -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "$SCREEN_TMP" -f "$TIMESTAMP" 2>&1)"
+  EXIT_CODE="$?"
+  assertNotEquals 0 "$EXIT_CODE"
+  assertContains "$OUTPUT" "Archive command exited with nonzero exit code"
+}
+
 test-screen-interface () {
   TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
   ./backup.sh -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "$SCREEN_TMP" -f "$TIMESTAMP"
@@ -129,6 +170,20 @@ test-tmux-interface () {
   assertEquals "$SCREEN_CONTENTS" "$EXPECTED_CONTENTS" 
 }
 
+test-rcon-interface () {
+  TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
+  ./backup.sh -w rcon -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "localhost:$RCON_PORT:$RCON_PASSWORD" -f "$TIMESTAMP"
+  EXPECTED_CONTENTS=$(echo -e "save-off\nsave-on\nsave-all") 
+  SCREEN_CONTENTS="$(head -n3 "$TEST_TMP/rcon-output")"
+  assertEquals "$SCREEN_CONTENTS" "$EXPECTED_CONTENTS" 
+}
+
+test-rcon-interface-wrong-password () {
+  TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
+  OUTPUT="$(./backup.sh -w RCON -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "localhost:$RCON_PORT:wrong$RCON_PASSWORD" -f "$TIMESTAMP" 2>&1)"
+  assertContains "$OUTPUT" "Wrong RCON password"
+}
+
 test-sequential-delete () {
   for i in $(seq 0 99); do
     TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01 +$i hour")"
@@ -138,6 +193,7 @@ test-sequential-delete () {
     TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01 +$i hour")"
     check-backup "$TIMESTAMP.tar.gz"
   done
+  assertEquals 10 "$(find "$TEST_TMP/backups" -type f | wc -l)" 
 }
 
 test-thinning-delete () {