-h

Display help message and exit.

-R

Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.BUGSErrors in the password or group files (such as invalid or duplicate entries) may cause these programs to loop forever or fail inother strange ways. Please run pwck and grpck to correct any such errors before converting to or from shadow passwords or groups.CONFIGURATIONThe following configuration variable in /etc/login.defs changes the behavior of grpconv and grpunconv:MAX_MEMBERS_PER_GROUP (number)Maximum members per group entry. When the maximum is reached, a new group entry (line) is started in /etc/group (with the samename, same password, and same GID).The default value is 0, meaning that there are no limits in the number of members in a group.This feature (split group) permits to limit the length of lines in the group file. This is useful to make sure that lines for NISgroups are not larger than 1024 characters.If you need to enforce such limit, you can use 25.Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should not use this variable unless youreally need it.The following configuration variables in /etc/login.defs change the behavior of pwconv:PASS_MAX_DAYS (number)The maximum number of days a password may be used. If the password is older than this, a password change will be forced. If notspecified, -1 will be assumed (which disables the restriction).PASS_MIN_DAYS (number)The minimum number of days allowed between password changes. Any password changes attempted sooner than this will be rejected. Ifnot specified, -1 will be assumed (which disables the restriction).PASS_WARN_AGE (number)The number of days warning given before a password expires. A zero means warning is given only upon the day of expiration, anegative value means no warning is given. If not specified, no warning will be provided.FILES/etc/login.defsShadow password suite configuration.