Sequential Erlang node name based on EPMD entries

node-name.sh

#!/usr/bin/env bash
# file: node-name.sh

set -eu

PREFIX=history
MAXNODES=100

DEFAULT=${PREFIX}_$(uuidgen | sed 's/-//g')

TEMP=$(mktemp)
REGISTERED=$TEMP.registered
SEQUENTIAL=$TEMP.sequential

# Generate potential names
for n in $(seq 1 $MAXNODES); do
  echo ${PREFIX}_$n
done > $SEQUENTIAL

# Filter out existing names and take the first free one
NODENAME=
if epmd -names 2>/dev/null | grep ${PREFIX} | cut -d' ' -f2 > $REGISTERED; then
  # fgrep -f requires a non-empty pattern file
  echo ${PREFIX}_$(expr $MAXNODES + 1) >> $REGISTERED
  NODENAME=$(fgrep -f $REGISTERED -v $SEQUENTIAL | head -1)
fi

# Did we get anything useful? If not, let's use the default UUID-based node name
if [ x"$NODENAME" == x"" ]; then
  NODENAME=$DEFAULT
fi

echo ${NODENAME}@${HOSTNAME}