Two-way folder sync with rsync - Inefficient but portable

twowayrsync

#!/usr/bin/env bash

remoteuser="$1"
remotehost="$2"
remotedir="$3"
localdir="$4"

syncstatusfile=".lastsync"

if [[ ! -d "$4" ]]; then
  echo "Usage:
twowayrsync <remoteuser> <remotehost> '<remotedir>' '<localdir>'
" >&2
  exit 1
fi

cd "${localdir}/"

if [[ -f "${localdir}/${syncstatusfile}" ]]; then
  # Delete local files that have been deleted remotely since the last sync and haven't been updated locally
  echo "Deleting locally:"
  rsync --dry-run --out-format="${localdir}/%n" --recursive --ignore-existing --links --specials "${localdir}/" ${remoteuser}@${remotehost}:"${remotedir}/" | tr '\n' '\0' | xargs -0 -P 10 -I % find % -maxdepth 0 -not -newercc "${syncstatusfile}" -print -exec rm -rf {} \;

  # Delete remote files that have been deleted locally since the last sync and haven't been updated remotely
  echo "Deleting remotely:"
  rsync --dry-run --out-format="${remotedir}/%n" --recursive --ignore-existing --links --specials ${remoteuser}@${remotehost}:"${remotedir}/" "${localdir}/" | tr '\n' '\0' | ssh ${remoteuser}@${remotehost} xargs -0 -P 10 -I % find % -maxdepth 0 -not -newercc "${remotedir}/${syncstatusfile}" -print -exec rm -rf {} \\\;
fi

# Update the sync time
touch "${syncstatusfile}"

# Add/update local files that are newer remotely
echo "Creating/updating locally:"
rsync --out-format="${localdir}/%n" --recursive --links --perms --times --specials --update --compress ${remoteuser}@${remotehost}:"${remotedir}/" "${localdir}/"

# Add/update remote files that are newer locally
echo "Creating/updating remotely:"
rsync --out-format="${remotedir}/%n" --recursive --links --perms --times --specials --update --compress "${localdir}/" ${remoteuser}@${remotehost}:"${remotedir}/"