Major refactor to support new backends

backup.sh

@@ -15,8 +15,7 @@ BACKUP_DIRECTORY="" # Directory to save backups in
 MAX_BACKUPS=128 # -1 indicates unlimited
 DELETE_METHOD="thin" # Choices: thin, sequential, none; sequential: delete oldest; thin: keep last 24 hourly, last 30 daily, and monthly (use with 1 hr cron interval)
 COMPRESSION_ALGORITHM="zstd" # Leave empty for no compression
-EXIT_IF_NO_SCREEN=false
+EXIT_IF_NO_SCREEN=false # Skip backup if there is no minecraft screen running
-USE_BORG_BACKUP=false # Use borg backup
 COMPRESSION_FILE_EXTENSION=".zst" # Leave empty for no compression; Precede with a . (for example: ".gz")
 COMPRESSION_LEVEL=3 # Passed to the compression algorithm
 ENABLE_CHAT_MESSAGES=false # Tell players in Minecraft chat about backup status
@@ -31,7 +30,6 @@ TIMESTAMP=$(date +$DATE_FORMAT)
 while getopts 'a:bcd:e:f:ghi:l:m:o:p:qs:v' FLAG; do
   case $FLAG in
     a) COMPRESSION_ALGORITHM=$OPTARG ;;
-    b) USE_BORG_BACKUP=true ;;
     c) ENABLE_CHAT_MESSAGES=true ;;
     d) DELETE_METHOD=$OPTARG ;;
     e) COMPRESSION_FILE_EXTENSION=".$OPTARG" ;;
@@ -39,7 +37,6 @@ while getopts 'a:bcd:e:f:ghi:l:m:o:p:qs:v' FLAG; do
     g) EXIT_IF_NO_SCREEN=true ;;
     h) echo "Minecraft Backup (by Nicolas Chan)"
        echo "-a    Compression algorithm (default: gzip)"
-       echo "-b    Use borg backup (default: false)"
        echo "-c    Enable chat messages"
        echo "-d    Delete method: thin (default), sequential, none"
        echo "-e    Compression file extension, exclude leading \".\" (default: gz)"
@@ -64,17 +61,14 @@ while getopts 'a:bcd:e:f:ghi:l:m:o:p:qs:v' FLAG; do
     q) SUPPRESS_WARNINGS=true ;;
     s) SCREEN_NAME=$OPTARG ;;
     v) DEBUG=true ;;
+    *) ;;
   esac
 done
 
-log-fatal () {
+BASE_DIR=$(dirname "$(realpath "$0")")
-  echo -e "\033[0;31mFATAL:\033[0m $*"
+
-}
+# shellcheck source=src/logging.sh
-log-warning () {
+source "$BASE_DIR/src/logging.sh"
-  if ! $SUPPRESS_WARNINGS; then
-    echo -e "\033[0;33mWARNING:\033[0m $*"
-  fi
-}
 
 # Check for missing encouraged arguments
 if [[ $SCREEN_NAME == "" ]]; then
@@ -91,237 +85,26 @@ if [[ $BACKUP_DIRECTORY == "" ]]; then
   log-fatal "Backup directory not specified (use -o)"
   MISSING_CONFIGURATION=true
 fi
-
 if $MISSING_CONFIGURATION; then
-  exit 0
-fi
-
-if $USE_BORG_BACKUP; then
-  ARCHIVE_FILE_NAME=$BACKUP_DIRECTORY
-  ARCHIVE_PATH="$BACKUP_DIRECTORY"::'{now}'
-else
-  ARCHIVE_FILE_NAME=$TIMESTAMP.tar$COMPRESSION_FILE_EXTENSION
-  ARCHIVE_PATH=$BACKUP_DIRECTORY/$ARCHIVE_FILE_NAME
-fi
-
-# Minecraft server screen interface functions
-message-players () {
-  local MESSAGE=$1
-  local HOVER_MESSAGE=$2
-  message-players-color "$MESSAGE" "$HOVER_MESSAGE" "gray"
-}
-execute-command () {
-  local COMMAND=$1
-  if ! $(screen -S "$SCREEN_NAME" -Q "select" . &> /dev/null); then
-    return 1
-  fi
-  if [[ "$SCREEN_NAME" != "" ]]; then
-    screen -S "$SCREEN_NAME" -p 0 -X stuff "$COMMAND$(printf \\r)"
-  fi
-}
-message-players-error () {
-  local MESSAGE=$1
-  local HOVER_MESSAGE=$2
-  message-players-color "$MESSAGE" "$HOVER_MESSAGE" "red"
-}
-message-players-success () {
-  local MESSAGE=$1
-  local HOVER_MESSAGE=$2
-  message-players-color "$MESSAGE" "$HOVER_MESSAGE" "green"
-}
-message-players-color () {
-  local MESSAGE=$1
-  local HOVER_MESSAGE=$2
-  local COLOR=$3
-  if $DEBUG; then
-    echo "$MESSAGE ($HOVER_MESSAGE)"
-  fi
-  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\":\"$HOVER_MESSAGE\"}]}}}]"
-  fi
-}
-
-# Parse file timestamp to one readable by "date" 
-parse-file-timestamp () {
-  local DATE_STRING=$(echo $1 | awk -F_ '{gsub(/-/,":",$2); print $1" "$2}')
-  echo $DATE_STRING
-}
-
-# Delete a backup
-delete-backup () {
-  local BACKUP=$1
-  rm -f $BACKUP_DIRECTORY/$BACKUP
-  message-players "Deleted old backup" "$BACKUP"
-}
-
-# Sequential delete method
-delete-sequentially () {
-  local BACKUPS=($(ls $BACKUP_DIRECTORY))
-  while [[ $MAX_BACKUPS -ge 0 && ${#BACKUPS[@]} -gt $MAX_BACKUPS ]]; do
-    delete-backup ${BACKUPS[0]}
-    BACKUPS=($(ls $BACKUP_DIRECTORY))
-  done
-}
-
-# Functions to sort backups into correct categories based on timestamps
-is-hourly-backup () {
-  local TIMESTAMP=$*
-  local MINUTE=$(date -d "$TIMESTAMP" +%M)
-  return $MINUTE
-}
-is-daily-backup () {
-  local TIMESTAMP=$*
-  local HOUR=$(date -d "$TIMESTAMP" +%H)
-  return $HOUR
-}
-is-weekly-backup () {
-  local TIMESTAMP=$*
-  local DAY=$(date -d "$TIMESTAMP" +%u)
-  return $((DAY - 1))
-}
-
-# Helper function to sum an array
-array-sum () {
-  SUM=0
-  for NUMBER in $*; do
-    (( SUM += NUMBER ))
-  done
-  echo $SUM
-}
-
-# Thinning delete method
-delete-thinning () {
-  # sub-hourly, hourly, daily, weekly is everything else
-  local BLOCK_SIZES=(16 24 30)
-  # First block is unconditional
-  # The next blocks will only accept files whose names cause these functions to return true (0)
-  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[@]})
-  if [[ $TOTAL_BLOCK_SIZE -gt $MAX_BACKUPS ]]; then
-    log-warning "MAX_BACKUPS ($MAX_BACKUPS) is smaller than TOTAL_BLOCK_SIZE ($TOTAL_BLOCK_SIZE)"
-  fi
-
-  local CURRENT_INDEX=0
-  local BACKUPS=($(ls -r $BACKUP_DIRECTORY)) # List newest first
-
-  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]}
-
-    if [[ $OLDEST_BACKUP_IN_BLOCK == "" ]]; then
-      break
-    fi
-
-    local OLDEST_BACKUP_TIMESTAMP=$(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
-    else
-      # Oldest backup in this block does not satisfy the condition for placement in next block
-      delete-backup $OLDEST_BACKUP_IN_BLOCK
-      break
-    fi
-
-    ((CURRENT_INDEX += BLOCK_SIZE))
-  done
-
-  delete-sequentially
-}
-
-# Delete old backups
-delete-old-backups () {
-  case $DELETE_METHOD in
-    "sequential") delete-sequentially
-      ;;
-    "thin") delete-thinning
-      ;;
-  esac
-}
-
-clean-up () {
-  # Re-enable world autosaving
-  execute-command "save-on"
-
-  # Save the world
-  execute-command "save-all"
-}
-
-trap-ctrl-c () {
-  log-warning "Backup interrupted. Attempting to re-enable autosaving"
-  clean-up
-  exit 2
-}
-
-trap "trap-ctrl-c" 2
-
-# Check if screen is running
-if ! $(screen -S "$SCREEN_NAME" -Q "select" . &> /dev/null); then
-  if $EXIT_IF_NO_SCREEN; then
-    log-warning "Screen \"$SCREEN_NAME\" is not running. Exiting without backing up (because of -g option)."
   exit 1
 fi
-fi
-
-# Notify players of start
-message-players "Starting backup..." "$ARCHIVE_FILE_NAME"
-
-# Disable world autosaving
-execute-command "save-off"
-
-# Record start time for performance reporting
-START_TIME=$(date +"%s")
-
-if $USE_BORG_BACKUP; then
-  borg create --compression "$COMPRESSION_ALGORITHM,$COMPRESSION_LEVEL" "$ARCHIVE_PATH" "$SERVER_WORLD"
-else
-  case $COMPRESSION_ALGORITHM in
-    "") # No compression
-      tar -cf $ARCHIVE_PATH -C $SERVER_WORLD .
-      ;;
-    *) # With compression
-      tar -cf - -C $SERVER_WORLD . | $COMPRESSION_ALGORITHM -cv -$COMPRESSION_LEVEL - > $ARCHIVE_PATH 2>> /dev/null
-      ;;
-esac
-fi
-
-sync
-END_TIME=$(date +"%s")
-
-clean-up 
-
-# Notify players of completion
-if $USE_BORG_BACKUP; then
-  BORG_LAST_ARCHIVE_INFO=$(borg info "$BACKUP_DIRECTORY" --last 1 --json)
-  BORG_REPO_INFO=$(borg info "$BACKUP_DIRECTORY" --json)
-
-  WORLD_SIZE_BYTES=$(echo "$BORG_LAST_ARCHIVE_INFO" | jq '.["archives"][0]["stats"]["original_size"]')
-  ARCHIVE_SIZE_BYTES=$(echo "$BORG_LAST_ARCHIVE_INFO" | jq '.["archives"][0]["stats"]["deduplicated_size"]')
-  BACKUP_DIRECTORY_SIZE=$(echo "$BORG_REPO_INFO" | jq '.["cache"]["stats"]["unique_csize"]' | numfmt --to=iec)
-else
-  WORLD_SIZE_BYTES=$(du -b --max-depth=0 $SERVER_WORLD | awk '{print $1}')
-  ARCHIVE_SIZE_BYTES=$(du -b $ARCHIVE_PATH | awk '{print $1}')
-  BACKUP_DIRECTORY_SIZE=$(du -h --max-depth=0 $BACKUP_DIRECTORY | awk '{print $1}')
-fi
-
-ARCHIVE_SIZE=$(numfmt --to=iec "$ARCHIVE_SIZE_BYTES")
-COMPRESSION_PERCENT=$(($ARCHIVE_SIZE_BYTES * 100 / $WORLD_SIZE_BYTES))
-TIME_DELTA=$((END_TIME - START_TIME))
-
-# Check that archive size is not null and at least 1024 KB
-if [[ "$ARCHIVE_SIZE" != "" && "$ARCHIVE_SIZE_BYTES" -gt 8 ]]; then
-  message-players-success "Backup complete!" "$TIME_DELTA s, $ARCHIVE_SIZE/$BACKUP_DIRECTORY_SIZE, $COMPRESSION_PERCENT%"
-  if ! $USE_BORG_BACKUP; then
-    delete-old-backups
-  fi
-else
-  message-players-error "Backup was not saved!" "Please notify an administrator"
-fi
 
+"$BASE_DIR/src/core.sh" \
+  "$BASE_DIR/src/exec-methods/screen.sh" \
+    -s "$SCREEN_NAME" \
+  -- \
+  "$BASE_DIR/src/backup-methods/tar.sh" \
+    -a "$COMPRESSION_ALGORITHM" \
+    -d "$DELETE_METHOD" \
+    -e "$COMPRESSION_FILE_EXTENSION" \
+    -f "$TIMESTAMP" \
+    -i "$SERVER_WORLD" \
+    -l "$COMPRESSION_LEVEL" \
+    -m "$MAX_BACKUPS" \
+    -o "$BACKUP_DIRECTORY" \
+  -- \
+    -c "$ENABLE_CHAT_MESSAGES" \
+    -g "$EXIT_IF_NO_SCREEN" \
+    -p "$PREFIX" \
+    -q "$SUPPRESS_WARNINGS" \
+    -v "$DEBUG"

src/backup-methods/tar.sh

@@ -0,0 +1,195 @@
+#!/bin/env bash
+
+# Backup to (compressed) tar archives, and automatically delete
+
+OPTIND=1
+while getopts 'a:d:e:f:i:l:m:o:' FLAG; do
+  case $FLAG in
+    a) COMPRESSION_ALGORITHM=$OPTARG ;;
+    d) DELETE_METHOD=$OPTARG ;;
+    e) COMPRESSION_FILE_EXTENSION=$OPTARG ;;
+    f) TIMESTAMP=$OPTARG ;;
+    i) SERVER_WORLD=$OPTARG ;;
+    l) COMPRESSION_LEVEL=$OPTARG ;;
+    m) MAX_BACKUPS=$OPTARG ;;
+    o) BACKUP_DIRECTORY=$OPTARG ;;
+    *) ;;
+  esac
+done
+
+ARCHIVE_FILE_NAME=$TIMESTAMP.tar$COMPRESSION_FILE_EXTENSION
+ARCHIVE_PATH=$BACKUP_DIRECTORY/$ARCHIVE_FILE_NAME
+mkdir -p "$BACKUP_DIRECTORY"
+
+# Parse file timestamp to one readable by "date"
+parse-file-timestamp () {
+  local DATE_STRING
+  DATE_STRING=$(echo "$1" | awk -F_ '{gsub(/-/,":",$2); print $1" "$2}')
+  echo "$DATE_STRING"
+}
+
+# Delete a backup
+delete-backup () {
+  local BACKUP=$1
+  rm -f "$BACKUP_DIRECTORY/$BACKUP"
+  message-players "Deleted old backup" "$BACKUP"
+}
+
+# Sequential delete method
+delete-sequentially () {
+  local BACKUPS_UNSORTED_RAW=("$BACKUP_DIRECTORY"/*)
+  local BACKUPS_UNSORTED=()
+  for BACKUP_NAME in "${BACKUPS_UNSORTED_RAW[@]}"; do
+    local BASENAME
+    BASENAME=$(basename "$BACKUP_NAME")
+    BACKUPS_UNSORTED+=("$BASENAME")
+  done
+  local BACKUPS=()
+  # List oldest first
+  while IFS='' read -r line; do BACKUPS+=("$line"); done < <(IFS=$'\n' sort <<<"${BACKUPS_UNSORTED[*]}")
+
+  while [[ $MAX_BACKUPS -ge 0 && ${#BACKUPS[@]} -gt $MAX_BACKUPS ]]; do
+    delete-backup "${BACKUPS[0]}"
+    local BACKUPS_UNSORTED_RAW=("$BACKUP_DIRECTORY"/*)
+    local BACKUPS_UNSORTED=()
+    for BACKUP_NAME in "${BACKUPS_UNSORTED_RAW[@]}"; do
+      local BASENAME
+      BASENAME=$(basename "$BACKUP_NAME")
+      BACKUPS_UNSORTED+=("$BASENAME")
+    done
+    local BACKUPS=()
+    # List oldest first
+    while IFS='' read -r line; do BACKUPS+=("$line"); done < <(IFS=$'\n' sort <<<"${BACKUPS_UNSORTED[*]}")
+  done
+}
+
+# Functions to sort backups into correct categories based on timestamps
+is-hourly-backup () {
+  local TIMESTAMP=$*
+  local MINUTE
+  MINUTE=$(date -d "$TIMESTAMP" +%M)
+  return "$MINUTE"
+}
+is-daily-backup () {
+  local TIMESTAMP=$*
+  local HOUR
+  HOUR=$(date -d "$TIMESTAMP" +%H)
+  return "$HOUR"
+}
+is-weekly-backup () {
+  local TIMESTAMP=$*
+  local DAY
+  DAY=$(date -d "$TIMESTAMP" +%u)
+  return $((DAY - 1))
+}
+
+# Helper function to sum an array
+array-sum () {
+  SUM=0
+  for NUMBER in "$@"; do
+    (( SUM += NUMBER ))
+  done
+  echo $SUM
+}
+
+# Thinning delete method
+delete-thinning () {
+  # sub-hourly, hourly, daily, weekly is everything else
+  local BLOCK_SIZES=(16 24 30)
+  # First block is unconditional
+  # The next blocks will only accept files whose names cause these functions to return true (0)
+  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[@]}")
+  if [[ $TOTAL_BLOCK_SIZE -gt $MAX_BACKUPS ]]; then
+    log-warning "MAX_BACKUPS ($MAX_BACKUPS) is smaller than TOTAL_BLOCK_SIZE ($TOTAL_BLOCK_SIZE)"
+  fi
+
+  local CURRENT_INDEX=0
+  local BACKUPS_UNSORTED_RAW=("$BACKUP_DIRECTORY"/*)
+  local BACKUPS_UNSORTED=()
+  for BACKUP_NAME in "${BACKUPS_UNSORTED_RAW[@]}"; do
+    local BASENAME
+    BASENAME=$(basename "$BACKUP_NAME")
+    BACKUPS_UNSORTED+=("$BASENAME")
+  done
+  local BACKUPS=()
+  # List newest first
+  while IFS='' read -r line; do BACKUPS+=("$line"); done < <(IFS=$'\n' sort -r <<<"${BACKUPS_UNSORTED[*]}")
+
+  for BLOCK_INDEX in "${!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]}
+
+    if [[ $OLDEST_BACKUP_IN_BLOCK == "" ]]; then
+      break
+    fi
+
+    local OLDEST_BACKUP_TIMESTAMP
+    OLDEST_BACKUP_TIMESTAMP=$(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
+    else
+      # Oldest backup in this block does not satisfy the condition for placement in next block
+      delete-backup "$OLDEST_BACKUP_IN_BLOCK"
+      break
+    fi
+
+    ((CURRENT_INDEX += BLOCK_SIZE))
+  done
+
+  delete-sequentially
+}
+
+
+clean-up () {
+  # Re-enable world autosaving
+  execute-command "save-on"
+
+  # Save the world
+  execute-command "save-all"
+}
+
+minecraft-backup-backup () {
+  case $COMPRESSION_ALGORITHM in
+    "") # No compression
+      tar -cf "$ARCHIVE_PATH" -C "$SERVER_WORLD" .
+      ;;
+    *) # With compression
+      tar -cf - -C "$SERVER_WORLD" . | $COMPRESSION_ALGORITHM -cv -"$COMPRESSION_LEVEL" - > "$ARCHIVE_PATH" 2>> /dev/null
+      ;;
+  esac
+  sync
+}
+
+minecraft-backup-check () {
+  WORLD_SIZE_BYTES=$(du -b --max-depth=0 "$SERVER_WORLD" | awk '{print $1}')
+  ARCHIVE_SIZE_BYTES=$(du -b "$ARCHIVE_PATH" | awk '{print $1}')
+  BACKUP_DIRECTORY_SIZE=$(du -h --max-depth=0 "$BACKUP_DIRECTORY" | awk '{print $1}')
+
+  ARCHIVE_SIZE=$(numfmt --to=iec "$ARCHIVE_SIZE_BYTES")
+  COMPRESSION_PERCENT=$((ARCHIVE_SIZE_BYTES * 100 / WORLD_SIZE_BYTES))
+  # Check that archive size is not null and at least 1024 KB
+  if [[ "$ARCHIVE_SIZE" != "" && "$ARCHIVE_SIZE_BYTES" -gt 8 ]]; then
+    echo "$ARCHIVE_SIZE/$BACKUP_DIRECTORY_SIZE, $COMPRESSION_PERCENT%"
+  else
+    return 1
+  fi
+}
+
+minecraft-backup-epilog () {
+  case $DELETE_METHOD in
+    "sequential") delete-sequentially
+      ;;
+    "thin") delete-thinning
+      ;;
+  esac
+}

src/core.sh

@@ -0,0 +1,185 @@
+#!/usr/bin/env bash
+
+# Minecraft server automatic backup management script
+# by Nicolas Chan
+# https://github.com/nicolaschan/minecraft-backup
+# MIT License
+#
+# For most convenience, run automatically with cron.
+
+# This script implements the core functionality, and expects the following
+# functions to be defined by the method scripts:
+#
+# minecraft-backup-execute "$COMMAND"
+#   where $COMMAND is a command sent to the Minecraft server console
+# minecraft-backup-backup
+#   which performs a backup
+# minecraft-backup-check
+# minecraft-backup-epilog
+
+# Default Configuration
+EXECUTE_METHOD="$1"
+shift
+EXECUTE_METHOD_OPTIONS=()
+while [[ $1 != "--" ]]; do
+  EXECUTE_METHOD_OPTIONS+=("$1")
+  shift
+done
+shift
+BACKUP_METHOD="$1"
+shift
+BACKUP_METHOD_OPTIONS=()
+while [[ $1 != "--" ]]; do
+  BACKUP_METHOD_OPTIONS+=("$1")
+  shift
+done
+shift
+
+while getopts 'c:g:p:q:v:' FLAG; do
+  case $FLAG in
+    c) ENABLE_CHAT_MESSAGES=$OPTARG ;;
+    g) EXIT_IF_NO_SCREEN=true ;;
+    p) PREFIX=$OPTARG ;;
+    q) SUPPRESS_WARNINGS=$OPTARG ;;
+    v) DEBUG=$OPTARG ;;
+    *) ;;
+  esac
+done
+
+BASE_DIR=$(dirname "$(realpath "$0")")
+
+# shellcheck source=logging.sh
+source "$BASE_DIR/logging.sh" \
+  -q "$SUPPRESS_WARNINGS" \
+  -v "$DEBUG"
+
+EXECUTE_METHOD_PATH=$EXECUTE_METHOD
+BACKUP_METHOD_PATH=$BACKUP_METHOD
+
+assert-all () {
+  local TEST_CMD=$1
+  local MESSAGE=$2
+  shift 2
+  local ITEMS=("$@")
+
+  local RESULT=true
+  for ITEM in "${ITEMS[@]}"; do
+    if ! $TEST_CMD "$ITEM"; then
+      log-fatal "$MESSAGE $ITEM"
+      RESULT=false
+    fi
+  done
+  if ! $RESULT; then
+    exit 1
+  fi
+}
+
+assert-files-exist () {
+  assert-all "test -f" "Script not found:" "$@"
+}
+
+assert-files-exist \
+  "$EXECUTE_METHOD_PATH" \
+  "$BACKUP_METHOD_PATH"
+
+# shellcheck source=exec-methods/screen.sh
+source "$EXECUTE_METHOD_PATH" "${EXECUTE_METHOD_OPTIONS[@]}"
+
+# shellcheck source=backup-methods/tar.sh
+source "$BACKUP_METHOD_PATH" "${BACKUP_METHOD_OPTIONS[@]}"
+
+# fn_exists based upon https://stackoverflow.com/q/85880
+fn_exists () {
+    LC_ALL=C type "$1" 2>&1 | grep -q 'function'
+}
+assert-functions-exist () {
+  assert-all fn_exists "Function not defined:" "$@"
+}
+
+assert-functions-exist \
+  minecraft-backup-execute \
+  minecraft-backup-backup \
+  minecraft-backup-check \
+  minecraft-backup-epilog
+
+# Minecraft server communication interface functions
+execute-command () {
+  minecraft-backup-execute "$@"
+}
+message-players () {
+  message-players-color "gray" "$@"
+}
+message-players-error () {
+  message-players-color "red" "$@"
+}
+message-players-warning () {
+  message-players-color "yellow" "$@"
+}
+message-players-success () {
+  message-players-color "green" "$@"
+}
+message-players-color () {
+  local COLOR=$1
+  local MESSAGE=$2
+  local HOVER_MESSAGE=$3
+  log-info "$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\":\"$HOVER_MESSAGE\"}]}}}]"
+  fi
+}
+
+clean-up () {
+  # Re-enable world autosaving
+  execute-command "save-on"
+
+  # Save the world
+  execute-command "save-all"
+}
+
+trap-ctrl-c () {
+  log-warning "Backup interrupted. Attempting to re-enable autosaving"
+  clean-up
+  exit 2
+}
+
+trap "trap-ctrl-c" 2
+
+# Notify players of start
+message-players "Starting backup..." "$TIMESTAMP"
+
+# Disable world autosaving
+execute-command "save-off"
+RESULT=$?
+if $EXIT_IF_NO_SCREEN && [[ $RESULT != "0" ]]; then
+  exit $RESULT
+fi
+
+# Record start time for performance reporting
+START_TIME=$(date +"%s")
+minecraft-backup-backup
+END_TIME=$(date +"%s")
+
+clean-up 
+
+TIME_DELTA=$((END_TIME - START_TIME))
+CHECK_MESSAGE=$(minecraft-backup-check)
+CHECK_RESULT=$?
+
+if [[ $CHECK_RESULT != "0" ]]; then
+  message-players-error "Backup failed!" "Please notify an admin."
+  exit $CHECK_RESULT
+fi
+
+message-players-success "Backup complete!" "$TIME_DELTA s, $CHECK_MESSAGE"
+
+EPILOG_MESSAGE=$(minecraft-backup-epilog)
+EPILOG_RESULT=$?
+
+if [[ $EPILOG_RESULT != "0" ]]; then
+  message-players-warning "Backup epilog failed."
+fi
+
+if [[ $EPILOG_MESSAGE != "" ]]; then
+  message-players "$EPILOG_MESSAGE"
+fi

src/exec-methods/screen.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+# Execute commands on a Minecraft server running in a GNU screen
+
+OPTIND=1
+while getopts 's:' FLAG "$@"; do
+  case $FLAG in
+    s) SCREEN_NAME=$OPTARG ;;
+    *) ;;
+  esac
+done
+
+minecraft-backup-execute () {
+    local COMMAND=$1
+    if ! screen -S "$SCREEN_NAME" -Q "select" .; then
+        return 1
+    fi
+    if [[ "$SCREEN_NAME" != "" ]]; then
+        screen -S "$SCREEN_NAME" -p 0 -X stuff "$COMMAND$(printf \\r)"
+    fi
+}

src/logging.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+SUPPRESS_WARNINGS=false
+DEBUG=true
+
+while getopts 'q:v:' FLAG; do
+  case $FLAG in
+    q) SUPPRESS_WARNINGS=$OPTARG ;;
+    v) DEBUG=$OPTARG ;;
+    *) ;;
+  esac
+done
+
+echo-colored () {
+  local COLOR_CODE="$1"
+  shift
+  local MESSAGE="$*"
+  if test -t 1 && [ "$(tput colors)" -gt 1 ]; then
+    # This terminal supports color
+    echo -ne "\033[${COLOR_CODE}m${MESSAGE}\033[0m"
+  else
+    # Output does not support color
+    echo -n "$MESSAGE"
+  fi
+}
+log () {
+  local COLOR="$1"
+  local TYPE="$2"
+  local MESSAGE="$3"
+  echo-colored "$COLOR" "${TYPE}: "
+  echo-colored "0" "$MESSAGE"
+  echo
+}
+log-fatal () {
+  >&2 log "0;31" "FATAL" "$*"
+}
+log-warning () {
+  if ! $SUPPRESS_WARNINGS; then
+    >&2 log "0;33" "WARNING" "$*"
+  fi
+}
+log-info () {
+  if $DEBUG; then
+    log "0;36" "INFO" "$*"
+  fi
+}