walletpassphrase "passphrase" timeout

The walletpassphrase RPC stores the wallet decryption key in memory for the indicated number of seconds. Issuing the `walletpassphrase` command while the wallet is already unlocked will set a new unlock time that overrides the old one.

*bitcoin-cli help walletpassphrase

walletpassphrase "passphrase" timeout

Stores the wallet decryption key in memory for 'timeout' seconds.
This is needed prior to performing transactions related to private keys such as sending bitcoins

Arguments:
1. "passphrase"     (string, required) The wallet passphrase
2. timeout            (numeric, required) The time to keep the decryption key in seconds; capped at 100000000 (~3 years).

Note:
Issuing the walletpassphrase command while the wallet is already unlocked will set a new unlock
time that overrides the old one.

Examples:

Unlock the wallet for 60 seconds
> bitcoin-cli walletpassphrase "my pass phrase" 60

Lock the wallet again (before 60 seconds)
> bitcoin-cli walletlock 

As json rpc call
> curl --user myusername --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "walletpassphrase", "params": ["my pass phrase", 60] }' -H 'content-type: text/plain;' http://127.0.0.1:8332/