predisHow can I use the Redis setnx command in PHP?

The setnx command in Redis is used to set a key only if it does not already exist. This can be used to ensure that a key is only ever set once.

In PHP, the setnx command can be used with the Redis class. The following example code will set the key mykey to the value myvalue only if the key does not already exist:

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);
$set = $redis->setnx('mykey', 'myvalue');
echo $set;

The output of the example code will be 1 if the key is successfully set, or 0 if the key already exists.

The parts of the example code are:

1. $redis = new Redis(); - creates a new instance of the Redis class.
2. $redis->connect('127.0.0.1', 6379); - connects to the Redis server.
3. $set = $redis->setnx('mykey', 'myvalue'); - sets the key mykey to the value myvalue only if it does not already exist.
4. echo $set; - prints the result of the setnx command.

For more information, see the PHP Redis documentation.

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