Set and get string keys in Redis, including expirations and conditional set
domain: redis.io · 8 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Store a string value: `SET mykey "Hello"` (returns OK).
Read it back: `GET mykey` (returns the value, or nil if the key does not exist).
Set with a timeout atomically: `SET anotherkey "will expire" EX 60` (expire after 60 seconds) - single atomic command, preferred over separate SET + EXPIRE.
Millisecond TTL: `SET k v PX 60000`; absolute Unix-time expiry with EXAT (seconds) or PXAT (ms).
Retain an existing TTL when overwriting: `SET k v KEEPTTL` (otherwise SET discards any prior TTL).
Conditional set: `SET k v NX` only sets if key does not exist; `SET k v XX` only if it already exists. This is the basis of simple locks.
Return the old value while setting: `SET k v GET` returns the previous value (since 6.2).
In redis-py: `r.set('k','v', ex=60)`, `r.get('k')`; node-redis: `client.set('k','v',{EX:60})`.
Known gotchas
A plain `SET` overwrites the key regardless of prior type AND clears any existing TTL - use KEEPTTL if you want the timeout preserved.
SET with NX/EX replaces the older SETNX/SETEX/PSETEX/GETSET commands, which Redis may deprecate/remove.
SET's NX atomic lock (SET resource token NX EX 30) works, but for distributed locks prefer the Redlock pattern and always release with a token-checking Lua script so you don't delete another owner's lock.
GET on a non-string type returns a WRONGTYPE error, not nil.
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