List non-expiring (ttl = -1) keys matchg pattern using "safe scan"

non_expiring_redis_keys.sh

#!/bin/bash

if [ "$#" -lt 2 ] 
then
    echo "Scan keys in Redis matching a pattern using SCAN (safe version of KEYS)"
    echo "Usage: $0 <host> [port] [database] [pattern] [count]"
    exit 1
fi
host=${1:-}
port=${2:-6379}
database=${3:-0}
pattern=${4:-\*}
count=${5:-10}
cursor=-1
keys=""

touch keys.txt
> keys.txt

while [[ "$cursor" -ne 0 ]]; do
    if [[ "$cursor" -eq -1 ]]
    then
        cursor=0
    fi

    reply=$(redis-cli -h "$host" -p "$port" -n "$database" SCAN "$cursor" MATCH "$pattern" COUNT "$count")
    cursor=$(expr "$reply" : '\([0-9]*[0-9 ]\)')
    keys=$(echo "$reply" | sed -e 's/^[0-9]\+//g')
    echo $keys >> keys.txt
done

cat keys.txt | sed -e 's/ /\n/g' | grep -v '^$' > keys.txt
cat keys.txt | xargs -n 1 -L 1 redis-cli -h "$host" -p "$port" -n "$database" TTL > ttl.txt

paste -d " " keys.txt ttl.txt | grep .*-1$ | cut -d " " -f 1 > nonexpiring.txt