PWCONV(8) System Management Commands PWCONV(8)

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

ÜBERSICHT

pwconv [options]

pwunconv [options]

grpconv [options]

grpunconv [options]

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_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.

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

-h, --help

zeigt die Hilfe an und beendet das Programm.

-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. No SELINUX support.

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.

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).

Der Standardwert ist 0, was bedeutet, dass die Anzahl der Mitglieder einer Gruppe nicht begrenzt ist.

Das Aufteilen von Gruppen ermöglicht es, Längenvorgaben für die Zeilen der Gruppendatei einzuhalten. Damit kann sichergestellt werden, dass die Zeilen für NIS-Gruppen nicht länger als 1024 Zeichen sind.

Falls Sie eine solche Begrenzung benötigen, können Sie 25 verwenden.

Hinweis: Mit aufgeteilten Gruppen können möglicherweise nicht alle Hilfsprogramme (nicht einmal jene der Shadow-Programmsammlung) umgehen. Sie sollten diese Variable nur setzen, wenn Sie sie wirklich benötigen.

The following configuration variables in /etc/login.defs change the behavior of pwconv:

PASS_MAX_DAYS (number)

die maximale Anzahl von Tagen, die ein Passwort verwendet werden darf. Wenn das Passwort älter ist, wird ein Wechsel des Passworts erzwungen. Falls nicht definiert, wird -1 angenommen, womit Passwörter unbefristet gelten.

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.

/etc/login.defs

konfiguriert die Shadow-Hilfsprogramme.

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

30.07.2026 shadow-utils 4.20.0