mbackup

#!/bin/bash
################################################################################
# mbackup - mobile backup using rsync.
################################################################################
unset copy_log exclude
interval=0
batt_interval=0
nice_level=20

script_name=$(basename ${0})
last_file="${HOME}/.${script_name}.last"
log_file="${HOME}/.${script_name}.log"
lock_file="${TMPDIR:-/tmp}/${script_name}.lock"
################################################################################

print_usage() {
cat <<EOM
Usage: ${script_name} [-b batt_interval [-c log_dest] [-e exclude-file]
       [-i interval] [-n nice] source destination

Syncs 'source' to 'destination' using rsync.  This tool is designed to be run
as a semi-frequent cron job, but only executes if the specified interval has
elapsed since the last backup.

Options:
    * -b batt_interval    interval to use when on battery power.
    * -c log_dest         copy the backup log to 'log_dest' if errors occur.
    * -e exclude_file     ignore entries in 'exclude_file' while backing up.
    * -i interval         number of hours between backups.
    * -n nice             niceness level; defaults to ${nice_level}.
EOM
}

on_battery() {
    pmset -g batt | grep 'Battery Power' &> /dev/null
}

while getopts "b:c:e:i:n:" flag; do
    case ${flag} in
    b) batt_interval=${OPTARG} ;;
    c) copy_log=${OPTARG} ;;
    e) exclude="--exclude-from=${OPTARG}" ;;
    i) interval=${OPTARG} ;;
    n) nice_level=${OPTARG} ;;
    ?) print_usage; exit 1 ;;
    esac
done

shift $((OPTIND - 1))
src=${1}
dest=${2}

if [[ -z "${src}" || -z "${dest}" ]]; then
    echo "error: source and destination not specified."
    print_usage
    exit 1
fi

if on_battery; then
    if [[ ${batt_interval} -gt 0 ]]; then
        interval=${batt_interval}
    fi
fi

# Only execute if (now - last) is greater or equal to the backup interval.
interval_secs=$((interval * 60 * 60))
last=$(cat "${last_file}" 2> /dev/null)
now=$(date +%s)
if [[ $((now - last)) -lt ${interval_secs} ]]; then
    exit 0
fi

# Don't run multiple instances.
if [[ -e "${lock_file}" ]]; then
    pid=$(cat "${lock_file}" 2> /dev/null)
    if ps "${pid}" &> /dev/null; then
        echo "Backup instance already running."
        exit 1
    fi
fi
echo $$ > "${lock_file}"

nice -n ${nice_level} \
        rsync -avz --delete-after --inplace --partial \
        --exclude=".${script_name}.log" \
        --exclude=".${script_name}.last" \
        "${exclude}" \
        "${src}" "${dest}" &> ${log_file}

result=$?
rm "${lock_file}"

if [[ ${result} -eq 0 ]]; then
    date +%s > "${last_file}"
else
    if [[ ${result} -ne 255 && -n "${copy_log}" ]]; then
        cp "${log_file}" "${copy_log}-$(date '+%F')"
    fi
    exit 1
fi