Manual: grpconv

PWCONV(8)					 System Management Commands					   PWCONV(8)

NAME
       pwconv, pwunconv, grpconv, grpunconv - convert to and from shadow passwords and groups

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 passwd from passwd and shadow and then removes shadow.

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

       The grpunconv command creates group from 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 main file are removed. Then, shadowed entries which don't have `x' as the
       password in the main file are updated. Any missing shadowed entries are added. Finally, passwords in the main file
       are replaced with `x'. These programs can be used for initial conversion as well to update the shadowed file if the
       main file is 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 main file are updated from the shadowed file. Entries
       which exist in the main 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
       shadow passwords or groups.

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 4.17.4					 02/02/2026						   PWCONV(8)