passowrd lock
       -S     This will output a short information about the status of the password for a given  account.

       -l     This  option  is  used to lock the specified account and it is available to root only. The locking is per-
              formed by rendering the encrypted password into an invalid string (by prefixing the encrypted string  with
              an !).

       -u     This is the reverse of the -l option - it will unlock the account password by removing the ! prefix.  This
              option  is available to root only. By default passwd will refuse to create a passwordless account (it will
              not unlock an account that has only "!" as a password).





Forces the user to change  password  at  the next  login
        -f    with -f the system wil force any login user to change his password
              Forces the user to change  password  at  the next  login  by  expiring  the  password for name. 

        -e    --expire Immediately expire an account's password. 
              This in effect can force a user to change his/her password at the user's next login.

# passwd

# passwd user1

echo "password01" | passwd --stdin user01

# passwd -S user01
user01 PS 2016-02-04 0 99999 7 -1 (Password set, MD5 crypt.)
#
# cat /etc/shadow |grep user01
user01:$1$LCAYp/8w$AXct0Zcd7P.sRCoQ1f59.0:16835:0:99999:7:::

# passwd -l user01
Locking password for user user01.
passwd: Success
#
# passwd -S user01
user01 LK 2016-02-04 0 99999 7 -1 (Password locked.)
#
# cat /etc/shadow |grep user01
user01:!!$1$LCAYp/8w$AXct0Zcd7P.sRCoQ1f59.0:16835:0:99999:7:::       <- !!
#


# passwd -u user01
Unlocking password for user user01.
passwd: Success.
#
# passwd -S user01
user01 PS 2016-02-04 0 99999 7 -1 (Password set, MD5 crypt.)
#

passwd -d user01

Linux Commands Cheat Sheet