Quickly tar up a folder

backdir

#!/bin/bash

##############################################
# File:   backdir
# Author: Dale C. Anderson
# Purpose: Small script to quickly back up a folder
##############################################


set -u     # Fail if an undeclared variable is used (helps when making changes / debugging)
umask 077  # Backups can contain sensitive info. Any files/folders we create should be private


# =============================================
# Prerequisites
# ---------------------------------------------

type readlink > /dev/null 2>&1 || {
  echo "This script depends on the 'readlink' utility, which was not found in PATH."
  exit 1
}

EXCLUSIONS="$0.exclusions"

# Show some help
if (( $# != 1 )); then
  echo ""
	echo "Usage: $(basename "$0") <dirname>"
	echo "Tars up the single folder you specify, places it in a 'backups' dir with a datestamp, and removes group and world permissions."
	echo "To exclude files from your archive, [create and] populate the TAR exclusions file in $EXCLUSIONS"
	echo ""
	exit 1
fi

# =============================================
# User Defined Functions
# ---------------------------------------------

function logdebug () {
: #  >&2 echo "$@"
}

function loginfo () {
: #  >&2 echo "$@"
}


function determine_archive_dir () {

  DIRS_TO_TRY=("./backups" "$HOME/backups" "/var/backups" "/backups")

  logdebug "Looking for an existing backup dir."

  for i in ${!DIRS_TO_TRY[@]}
  do
    DIR=$(readlink -e "${DIRS_TO_TRY[i]}") || { logdebug "dir does not exist: ${DIRS_TO_TRY[i]}" ; continue; }
    logdebug "trying $DIR"
    if [ -d "$DIR" ] && [ -w "$DIR" ]; then
      logdebug "Found one."
      echo "$DIR"
      return
    fi
    logdebug "not a dir, or not writeable"
  done


  logdebug "No existing backup dirs exist, or none are writable. Will try to create one instead."

  for i in ${!DIRS_TO_TRY[@]}
  do
    DIR=$(readlink -f "${DIRS_TO_TRY[i]}") || continue
    logdebug "trying $DIR"
    [ ! -e "$DIR" ] \
    && mkdir "$DIR" > /dev/null 2>&1 && {
      loginfo "Created $DIR"
      echo "$DIR"
      return
    }
  done

  # Can we write to the current directory?

  DIR=$(readlink -e ".")
  if [ -d "$DIR" ] && [ -w "$DIR" ]; then
    logdebug "Found one."
    echo "$DIR"
    return
  fi

  # Can we at least write to the home dir?

  DIR="$HOME"
  if [ -d "$DIR" ] && [ -w "$DIR" ]; then
    logdebug "Found one."
    echo "$DIR"
    return
  fi

  >&2 echo "Could not find any suitable writeable directories. Aborting."
  exit 1
}



# =============================================
# Getting ready for processing
# ---------------------------------------------

DIR_TO_BACK_UP=$(readlink -e "${1}") || {
  echo "Not found: $1"
  exit 1
}
loginfo "Backing up ${DIR_TO_BACK_UP}..."
ARCHIVEDIR=$(determine_archive_dir)
loginfo "ARCHIVEDIR: $ARCHIVEDIR"

TARFILE="$ARCHIVEDIR/$(basename "$DIR_TO_BACK_UP").$(date +%Y-%m-%d-%H%M).tgz"
loginfo "TARFILE: $TARFILE"



# =============================================
# Sanity checking
# ---------------------------------------------

if [ "$DIR_TO_BACK_UP" == "/" ]; then
  echo "Sorry, you need to use a more robust tool to back up the root directory."
  exit 1
fi;

if [ ! -d "$DIR_TO_BACK_UP" ]; then
  echo "Not found (or not a directory): $DIR_TO_BACK_UP"
  exit 1
fi;

if [ "$DIR_TO_BACK_UP" == "$(dirname "$TARFILE")" ]; then
  echo "You can't back up the directory that the backup is being saved to."
  exit 1
fi;


# =============================================
# UND NOw VE DANCE
# ---------------------------------------------

# Use exclusions if they are specified
echo -n "Backing up ${DIR_TO_BACK_UP}"
DIR_WITHOUT_LEADING_SLASH=$(echo "$DIR_TO_BACK_UP"| sed -e 's/^\///')
if [ -f "$EXCLUSIONS" ]; then
  echo " using exclusions specified from ${EXCLUSIONS}..."
  tar --create --file "$TARFILE" --gzip --directory / "$DIR_WITHOUT_LEADING_SLASH" --exclude-from="$EXCLUSIONS"
else
  echo "..."
  tar --create --file "$TARFILE" --gzip --directory / "$DIR_WITHOUT_LEADING_SLASH"
fi

BYTES_WRITTEN=$(wc -c <"$TARFILE")
echo "Saved $TARFILE (${BYTES_WRITTEN} bytes)"