The pwconv command creates and updates /etc/shadow with information from /etc/passwd.
pwconv relies on a special value of 'x' in the password field of /etc/passwd. This value of 'x' indicates that the password for the user is already in /etc/shadow and should not be modified.
If the /etc/shadow file does not exist, this command will create /etc/shadow with information from /etc/passwd. The command populates /etc/shadow with the user's login name, password, and password aging information. If password aging information does not exist in /etc/passwd for a given user, none will be added to /etc/shadow. However, the last changed information will always be updated.
If the /etc/shadow file does exist, the following tasks will be performed:
Entries that are in the /etc/passwd file and not in the /etc/shadow file will be added to the /etc/shadow file.
Entries that are in the /etc/shadow file and not in the /etc/passwd file will be removed from /etc/shadow.
Password attributes (for example, password and aging information) that exist in an /etc/passwd entry will be moved to the corresponding entry in /etc/shadow.
The pwconv command can only be used by the super-user.
See attributes(5) for descriptions of the following attributes:
pwconv exits with one of the following values:
Invalid command syntax.
Unexpected failure. Conversion not done.
Unexpected failure. Password file(s) missing.
Password file(s) busy. Try again later.
Bad entry in /etc/shadow file.