CentOS: 7.x
Samba: 4.4.4

Just a quick note. If you want to list the users in your smbpasswd file, you can use the pdbedit command.

# pdbedit -L
No builtin backend found, trying to load plugin
Module ‘tdbsam’ loaded
username:1002:

Or, for more detailed output:

# pdbedit -L -v
No builtin backend found, trying to load plugin
Module ‘tdbsam’ loaded
—————
Unix username: username1
NT username:
Account Flags: [U ]
User SID: S-1-5-21-856554280-4097225363-552893113-1000
Forcing Primary Group to ‘Domain Users’ for username1
Primary Group SID: S-1-5-21-856554280-4097225363-552893113-513
Full Name:
Home Directory: \\server\username1
HomeDir Drive:
Logon Script:
Profile Path: \\server\username1\profile
Domain: SERVER
Account desc:
Workstations:
Munged dial:
Logon time: 0
Logoff time: Wed, 06 Feb 2036 07:06:39 PST
Kickoff time: Wed, 06 Feb 2036 07:06:39 PST
Password last set: Thu, 19 Jan 2017 15:10:20 PST
Password can change: Thu, 19 Jan 2017 15:10:20 PST
Password must change: never
Last bad password : 0
Bad password count : 0
Logon hours : FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
—————
Unix username: username2
NT username:
Account Flags: [U ]
User SID: S-1-5-21-856554280-4097225363-552893113-1001
Forcing Primary Group to ‘Domain Users’ for username2
Primary Group SID: S-1-5-21-856554280-4097225363-552893113-513
Full Name:
Home Directory: \\server\username2
HomeDir Drive:
Logon Script:
Profile Path: \\server\username2\profile
Domain: SERVER
Account desc:
Workstations:
Munged dial:
Logon time: 0
Logoff time: Wed, 06 Feb 2036 07:06:39 PST
Kickoff time: Wed, 06 Feb 2036 07:06:39 PST
Password last set: Mon, 20 Mar 2017 16:08:57 PDT
Password can change: Mon, 20 Mar 2017 16:08:57 PDT
Password must change: never
Last bad password : 0
Bad password count : 0
Logon hours : FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

You can add users to the smbpasswd file as follows:

# smbpasswd -a username3