What command would I use to expire keys in Redis that have less than 5 days to live?

Question

Sessions in my db are being set as a hash:

1) "sid:lpg3um654ckqp7tj7fkr2qs2Zz" (this has a ttl of a week)
2) "sid:lpg3um654ckqp7tj7fkr2qs2Yy" (this has a ttl of 6 days)
3) "sid:g6sftph5dnun5bk6l0hqyyh6p5" (this has a ttl of 5 days)
4) "sid:g6sftph5dnun5bk6l0hqyxh6x3" (this has a ttl of 4 days)
5) "sid:g6sftph5dnun5bk6l0hqyxh4t1" (this has a ttl of 3.5 days)

I know you can set a ttl on a single key from the command line, but how would you do that for a batch of keys that are going to expire in a certain period of time (i.e. less than 5 days ttl). Running said command should result in deleting entries 4 and 5.

Answer 1

Here's a Lua script (must... honor... the... tag...) that uses DEL to remove the sid:'s according to your definition (despite my comment re. KEYS's use, since Lua scripts are atomic there's no need to SCAN here and DEL won't work anyway since SCAN is random) and returns the names of deleted keys:

local exp=ARGV[1] * 60 * 60 * 24;
local exs={};
local keys=redis.call('keys', 'sid:*');

for _,v in next,keys,nil do
  local ttl=redis.call('ttl', v);
  if ttl < exp then
    redis.call('del', v);
    exs[#exs + 1] = v;
  end
end

return exs;

Note: this script is anything by safe to use and could probably kill your production instance (not to mention it not being cluster safe) ;)

Answer 2

#!/bin/bash
FIVEDAYS=432000

redis-cli KEYS  "*" |
while read LINE;
do TTL=`redis-cli ttl $LINE `;
  if [ $TTL -le $FIVEDAYS ]; 
      then `redis-cli expire $LINE 5`;
      echo "Deleted $LINE";
  fi;
done;