regisshtry-receive

#!/usr/bin/env bash

# place this script into your remote hosts $PATH

if [ "$#" -ne 1 ]; then
    echo "usage: $0 image"
    exit 1
fi

FILENAME=$1
mkdir -p `dirname $FILENAME`
LOCKFILE="${FILENAME}.lock"

# lock it
exec 200>$LOCKFILE
flock -n 200 || \
        { echo "An other upload is already in progress"; exit 1; }
pid=$$
echo $pid 1>&200

version=1

while [ -f "${FILENAME}.${version}" ]
do
  (( version++ ))
done

VERSION_FILENAME="${FILENAME}.${version}"

echo "Uploading ..."
cat > $VERSION_FILENAME && \
ln -sf $VERSION_FILENAME $FILENAME && \
rm $LOCKFILE