epixoip

#!/bin/bash
# Wed Aug 26 19:25:48 PDT 2009 by epixoip (epixoip@hush.com) and xirgot (jburks@gmail.com)

function usage() {
cat <<EOF
powerboost - ensures comcast powerboost speeds for duration of download
Syntax: $0 [options] URL

Options:
        -t      Number of concurrent "threads"
        -o      Output file name
        -h      Display this message

EOF
exit 1
}

function error() {
        echo "error: $1" >&2
        exit 1
}

function warn() {
        echo "warning: $1" >&2
}

function spawn_thread() {
        if [[ $got -lt $length ]]; then
                for ((i=1;i<=$1;i++)) {
                        sbyte=$((got + 1))
                        remain=$(expr $length - $sbyte)
                        if [[ $remain -lt 9999999 ]]; then
                                ebyte=$length
                                got=$length
                        elif [[ $remain -ge 9999999 ]]; then
                                ebyte=$(expr $got + 9999999)
                                got=$(expr $got + 9999999)
                        fi
                        chunk=$((chunk + 1))
                        curl -s -o ${outfile}.${chunk} -r ${sbyte}-${ebyte} $url &
                        echo "Retrieving chunk ${sbyte}-${ebyte}..."
                }
        fi
}

function thread_exit() {
        spawn_thread 1
}

while getopts "ht:o:" opts; do
        case $opts in
                t) threads="$OPTARG";;
                o) outfile="$OPTARG";;
                h) usage;;
                v) verbose=1;;
                ?) usage;;
        esac
        x="$OPTIND"
done

if [[ "$x" > 0 ]]; then shift $(($x-1)); fi
if [[ -z "$1" ]]; then usage; fi

url="$1"
threads="${threads:-4}"
outfile="${outfile:-$(basename $url)}"
length="$(curl -I $url 2>&1 | grep -i 'content-length:' | awk '{print $2}' | sed -e 's/\n//g' -e 's/\r//g')"

if [[ -z "$length" ]]; then error "$(basename $url) does not exist on server $(dirname $url)"; fi

maxthreads=$((length / 10000000))
if [[ $threads > $maxthreads ]]; then
        warn "more threads were called than needed; reducing threads to $maxthreads"
        threads=$maxthreads
fi

if [[ $length -le 10000000 ]]; then
        warn "file is less than 10MB; no benefit from using this script. downloading anyway."
        curl -o ${outfile} ${url} 2>&1
else
        got=-1
        chunk=0
        spanwed=0
        stime=$(date +%s)

        set -o monitor
        spawn_thread $threads
        trap thread_exit CHLD
        wait

        etime=$(date +%s)
        elapsed=$((etime - stime))
        arate=$(echo "scale=2; $length / $elapsed" | bc -l)
        echo "Retrieved $length bytes in $elapsed seconds [avg $arate bytes/sec]"

        echo "Concatenating chunks and cleaning up..."
        for ((i=1;i<=$chunk;i++)) { cat ${outfile}.${i} >>${outfile}; rm -f ${outfile}.${i}; }

        echo "Done!"
fi