arms

#!/bin/bash
#
# ARMS Remote Mirror System
# Copyright (C) 2014 SitePoint Pty Ltd
#
# Contact details provided at http://www.sitepoint.com/
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


## Variables
#

declare -r ionice_cmd="ionice -c 2 -n 7"
declare -r hostName="${1}"
declare -r srcPath="${2}"
declare -r dstPath="${3}"
declare -r lockFile="/var/run/arms.pid"
declare -r bwLimit="0"

# There should be no reason to touch anything below this line.
declare -r scriptName="$(basename ${0})"
declare -ri verbose=0



## Functions
#

function doSafetyChecks()
{
    # Check we're running as root.
    if [ "${UID}" -ne 0 ]
    then
        printError "Must be run as root."
        exit 1
    fi

    if [ ! -d "${srcPath}" ]
    then
        printError "Source directory '${srcPath}' not found."
        exit 1
    fi

    ping -c 1 "${hostName}" >/dev/null
    if [ "${?}" -ne 0 ]
    then
        {
            echo "Warning: Cannot ping host '${hostName}'."
            echo "We may fail at running rsync later."
        } 1>&2
    fi
}

function printError()
{
    echo "Error: ${@}" 1>&2
}

function setLockFile()
{
    declare cmdAtPID

    # If the lockfile exists
    if [ -f "${lockFile}" ]
    then
        # If the lockfile points to a process by the same name
        cmdAtPID="$(ps -p $(cat "${lockFile}") -o comm=)"
        echo "${cmdAtPID}" | grep -q "^${scriptName}$"
        if [ "${?}" -eq 0 ]
        then
            # Wait 10 minutes and try again.
            echo "Sleeping, waiting for the lock to free up."
            sleep 600
            setLockFile
        else
            # Old lock file. Overwrite it.
            echo ${$} > "${lockFile}"
        fi
    else
        echo ${$} > "${lockFile}"
    fi
}

function delLockFile()
{
    rm -f "${lockFile}"
}

function rsyncCmd()
{
    function rsyncFailMsg()
    {
        {
            echo -n "Warning: Rsync from "
            echo -n "root@${hostName}:${dstPath} "
            echo "failed."
        } >&2
    }

    declare -i rsyncFail=0
    declare cmdWrap="${ionice_cmd}"

    # Used by the bash time command.
    TIMEFORMAT=$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'

    [ "${verbose}" -ne 0 ] && cmdWrap="time ${cmdWrap}"

    eval ${cmdWrap} rsync -aH -e \'ssh -q\' --delete \
        $([ -n "${bwLimit}" ] && echo --bwlimit=${bwLimit}) \
        ${srcPath} root@${hostName}:${dstPath} || rsyncFail=1

    if [ "${rsyncFail}" -ne 0 ]
    then
        rsyncFailMsg
    fi

    # Formatting improvements
    if [ "${verbose}" -ne 0 ]
    then
        echo -e '\n'
    fi
}


## Begin execution
#

doSafetyChecks
setLockFile
rsyncCmd
delLockFile

# EOF