How to check the lock status of any user account in Linux

As you can see above two exclamation mark (!!) before the encrypted password which means that the password has been locked

To unlock the password
# passwd -u user1
Unlocking password for user user1.
passwd: Success

Case 2: Account is Locked

In this case the user account might have been locked by the administrator

To lock an account
# usermod -L user1
Review your /etc/shadow file for the changes

As you see an extra single exclamation mark(!) appeared in the password section before the encrypted password starts which signifies that the user account is locked

To unlock a user account
# usermod -U user1

Case 3: Password never set

This can also be the scenario where the administrator has not assigned any password due to which the user is not able to login

So to verify this again you need to check your /etc/shadow file
# grep user1 /etc/shadow
user1:!!:16299:0:99999:7:::
As you see two exclamation mark(!!) is there but no encrypted password which means a password is not set.

If the password was set without lock your /etc/shadow would look like something below

Check the lock status of any Linux Account

Now one single command to see the lock status of the user
# passwd -S user1
user1 LK 2014-08-17 0 99999 7 -1 (Password locked.)