config() {
  NEW="$1"
  OLD="$(dirname $NEW)/$(basename $NEW .new)"
  # If there's no config file by that name, mv it over:
  if [ ! -r $OLD ]; then
    mv $NEW $OLD
  elif [ "$(cat $OLD | md5sum)" = "$(cat $NEW | md5sum)" ]; then
    # toss the redundant copy
    rm $NEW
  fi
  # Otherwise, we leave the .new copy for the admin to consider...
}

# Group for all taler exchange users.
if ! getent group taler >/dev/null; then
  groupadd taler \
    --system \
    || true
fi

# Group for all Taler users with direct database access.
if ! getent group taler-exchange-db >/dev/null; then
  groupadd taler-exchange-db \
    --system \
    || true
fi

# Group for processes with access to online signing keys.
if ! getent group taler-exchange-secmod >/dev/null; then
  groupadd taler-exchange-secmod \
    --system \
    || true
fi

# Group for the access to the offline private key.
if ! getent group taler-exchange-offline >/dev/null; then
  groupadd taler-exchange-offline \
    --system \
    || true
fi

if ! getent passwd taler-exchange-offline >/dev/null; then
  useradd taler-exchange-offline \
    --comment 'Runs the HTTP daemon with the core business logic' \
    --groups taler-exchange-db \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-secmod-rsa >/dev/null; then
  useradd taler-exchange-secmod-rsa \
    --comment 'Manages the RSA private online signing keys' \
    --gid taler \
    --groups taler-exchange-secmod \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-secmod-cs >/dev/null; then
  useradd taler-exchange-secmod-cs \
    --comment 'Manages the CS private online signing keys' \
    --gid taler \
    --groups taler-exchange-secmod \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-secmod-eddsa >/dev/null; then
  useradd taler-exchange-secmod-eddsa \
    --comment 'Manages the EdDSA private online signing keys' \
    --gid taler \
    --groups taler-exchange-secmod \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-closer >/dev/null; then
  useradd taler-exchange-closer \
    --comment 'Closes idle reserves by triggering wire transfers that refund the originator' \
    --gid taler \
    --groups taler-exchange-db \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-aggregator >/dev/null; then
  useradd taler-exchange-aggregator \
    --comment 'Aggregates deposits into larger wire transfer requests' \
    --gid taler \
    --groups taler-exchange-db \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-transfer >/dev/null; then
  useradd taler-exchange-transfer \
    --comment 'Performs wire transfers with the bank (via LibEuFin/Nexus)' \
    --gid taler \
    --groups taler-exchange-db \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-wirewatch >/dev/null; then
  useradd taler-exchange-wirewatch \
    --comment 'Checks for incoming wire transfers with the bank (via LibEuFin/Nexus)' \
    --gid taler \
    --groups taler-exchange-db \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

if ! getent passwd taler-exchange-offline >/dev/null; then
  useradd taler-exchange-offline \
    --comment 'User for the access to the offline private key.' \
    --gid taler \
    --groups taler-exchange-offline \
    --system \
    --home-dir /var/lib/taler \
    || true
fi

config etc/httpd/sites-available/taler-exchange.conf.new
config etc/rc.d/rc.taler-exchange.new
config etc/taler/conf.d/exchange-business.conf.new
config etc/taler/conf.d/exchange-coins.conf.new
config etc/taler/conf.d/exchange-system.conf.new
config etc/taler/secrets/exchange-accountcredentials-1.secret.conf.new
config etc/taler/secrets/exchange-db.secret.conf.new

chown root:taler etc/taler/secrets
chown root:taler var/cache/taler
chown root:taler var/lib/taler
chown root:taler var/log/taler

chown :taler etc/taler/secrets/exchange-accountcredentials-1.secret.conf.new
chown :taler-exchange-db etc/taler/secrets/exchange-db.secret.conf.new
chown :taler-exchange-db etc/taler/secrets/exchange-db.secret.conf.new