How to lock and unlock Linux  user ?

1. Example:

To lock the password:

# passwd -l oracle

Locking password for user oracle.

passwd: Success

Check :more /etc/shadow

Before Lock:

oracle:$1$3qMtw2cK$LJwR4.e9dY.axeCfEi9zY0:18583:1::7:::

After lock:

oracle:!!$1$3qMtw2cK$LJwR4.e9dY.axeCfEi9zY0:18583:1::7:::

Check two exclamation mark (!!) before the encrypted password which means that the password has been locked

To unlock the password:

# passwd -u oracle

2. Example:

# passwd -l oracle   >>> Lock the Oracle user

Locking password for user oracle.

passwd: Success

# passwd -S oracle   >>>> To check lock/unlock Linux user

oracle LK 2020-11-17 1 -1 7 -1 (Password locked.)

# passwd -u oracle    >>>> Unlock Linux user

Unlocking password for user oracle.

passwd: Success

# passwd -S oracle

oracle PS 2020-11-17 1 -1 7 -1 (Password set, MD5 crypt.)