chgpasswd - 批量更新组密码

chgpasswd [选项]

The chgpasswd command reads a list of group name and password pairs from standard input and uses this information to update a set of existing groups. Each line is of the format:


By default the supplied password must be in clear-text, and is encrypted by chgpasswd.

The default encryption algorithm can be defined for the system with the ENCRYPT_METHOD variable of /etc/login.defs, and can be overwritten with the -e, -m, or -c options.


The options which apply to the chgpasswd command are:

-c, --crypt-method


可用的方法有 DES, MD5, NONE, and SHA256 或 SHA512,前提是您的 libc 支持这写方法。

-e, --encrypted


-h, --help


-m, --md5

如果提供的密码没有加密,则使用 MD5 加密而不是 DES。

-R, --root CHROOT_DIR

Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.

-s, --sha-rounds


值 0 表示让系统为加密方法选择默认的轮转次数 (5000)。

会强制最小 1,000,最大 9,9999,9999

您只可以对 SHA256 或 SHA512 使用此选项。

By default, the number of rounds is defined by the SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS variables in /etc/login.defs.



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



It can take one of these values: DES (default), MD5, SHA256, SHA512.

Note: this parameter overrides the MD5_CRYPT_ENAB variable.


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).

默认值是 0,意味着组中的成员数没有限制。

此功能(分割组)允许限制组文件中的行长度。这对于确保 NIS 组的行比长于 1024 字符。

如果要强制这个限制,可以使用 25。

注意:分割组可能不受所有工具的支持(甚至在 Shadow 工具集中)。您不应该使用这个变量,除非真的需要。

MD5_CRYPT_ENAB (boolean)

Indicate if passwords must be encrypted using the MD5-based algorithm. If set to yes, new passwords will be encrypted using the MD5-based algorithm compatible with the one used by recent releases of FreeBSD. It supports passwords of unlimited length and longer salt strings. Set to no if you need to copy encrypted passwords to other systems which don't understand the new algorithm. Default is no.

This variable is superseded by the ENCRYPT_METHOD variable or by any command line option used to configure the encryption algorithm.

This variable is deprecated. You should use ENCRYPT_METHOD.


When ENCRYPT_METHOD is set to SHA256 or SHA512, this defines the number of SHA rounds used by the encryption algorithm by default (when the number of rounds is not specified on the command line).

使用很多轮转,会让暴力破解更加困难。但是需要注意,认证用户时也会需要更多的 CPU 资源。

如果没有指定,libc 会选择默认的轮转数(5000)。

值必须在 1000 - 999,999,999 之间。

If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS values is set, then this value will be used.

If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest value will be used.





Shadow 密码套件配置。

gpasswd(1), groupadd(8), login.defs(5).
2020-01-23 shadow-utils 4.8.1