PWCONV(8)		  System Management Commands		     PWCONV(8)

NAME
       pwconv, pwunconv, grpconv, grpunconv - convert between the system's
       shadowed and plain account files

SYNOPSIS
       pwconv [options]

       pwunconv [options]

       grpconv [options]

       grpunconv [options]

DESCRIPTION
       The pwconv command creates shadow from passwd and an optionally
       existing shadow.

       The pwunconv command creates a plain passwd from shadowed passwd and
       shadow and then removes shadow.

       The grpconv command creates gshadow from group and an optionally
       existing gshadow.

       The grpunconv command creates plain group from shadowed group and
       gshadow and then removes gshadow.

       These four programs all operate on the normal and shadow password and
       group files: /etc/passwd, /etc/group, /etc/shadow, and /etc/gshadow.

       Each program acquires the necessary locks before conversion.  pwconv
       and grpconv are similar. First, entries in the shadowed file which
       don't exist in the plain file are removed. Then, entries in the
       shadowed file which don't have `x' as the password in plain file are
       updated. Any missing shadowed entries are added. Finally, passwords in
       the plain file are replaced with `x'. These programs can be used for
       initial conversion as well to update the shadowed file if the plain
       file has been edited by hand.

       pwconv will use the values of PASS_MIN_DAYS, PASS_MAX_DAYS, and
       PASS_WARN_AGE from /etc/login.defs when adding new entries to
       /etc/shadow.

       Likewise pwunconv and grpunconv are similar. Passwords in the plain
       file are updated from the shadowed file. Entries which exist in the
       plain file but not in the shadowed file are left alone. Finally, the
       shadowed file is removed. Some password aging information is lost by
       pwunconv. It will convert what it can.

OPTIONS
       The options which apply to the pwconv, pwunconv, grpconv, and grpunconv
       commands are:

       -h, --help
	   Display help message and exit.

       -R, --root CHROOT_DIR
	   Apply changes in the CHROOT_DIR directory and use the configuration
	   files from the CHROOT_DIR directory. Only absolute paths are
	   supported.

BUGS
       Errors in the password or group files (such as invalid or duplicate
       entries) may cause these programs to loop forever or fail in other
       strange ways. Please run pwck and grpck to correct any such errors
       before converting to or from shadowed files.

CONFIGURATION
       The 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 same name,
	   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 NIS
	   groups 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 you
	   really 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 not
	   specified, -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. If
	   not specified, 0 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, a value of
	   -1 means no warning is given. If not specified, no warning will be
	   provided.

FILES
       /etc/login.defs
	   Shadow password suite configuration.

SEE ALSO
       grpck(8), login.defs(5), pwck(8).

shadow-utils 4.18.0		  06/27/2025			     PWCONV(8)