Added threading

retroarch_update_cores

#!/usr/bin/env bash
# github.com/cpinkus

update_core()
{
    path="$1"
    corename="$(basename $path)"
    timestamp_old="$(grep $corename $cores_path/.timestamps.old)"
    timestamp_new="$(grep $corename $cores_path/.timestamps.new)"
    if [[ "$timestamp_new" == "$timestamp_old" ]]
    then
        echo "Core $corename already up-to-date"
        return
    fi
    curl -s -o "$cores_path/$corename.zip" "$cores_url/$corename.zip"
    unzip -q -o -d "$cores_path" "$cores_path/$corename.zip"
    rm "$cores_path/$corename.zip"
    echo "Core $corename updated"
}

### URL to download cores from
cores_url=http://buildbot.libretro.com/nightly/linux/x86_64/latest
### Location of your retroarch cores
cores_path="$HOME"/.config/retroarch/cores


# Get timestamps from URL
touch "$cores_path"/.timestamps.old
touch "$cores_path"/.timestamps.new
mv "$cores_path"/.timestamps.new "$cores_path"/.timestamps.old
curl -s "$cores_url"/ | sed 's/<[^>]\+>/\'$'\n/g' | grep -A3 "_libretro.so.zip" \
| tr '\n' ' ' | sed 's/ -- /\'$'\n/g' > "$cores_path"/.timestamps.new

# Get the number of cores
threads=`grep -c ^processor /proc/cpuinfo`

# Download and replace cores
for i in "$cores_path"/*_libretro.so
do
    while [ `jobs | wc -l` -ge $threads ]
    do
        sleep 1
    done
    update_core "$i" &
done

wait