Ubuntu Manpage: chgpasswd - 批量更新组密码

Provided by: passwd_4.17.4-2ubuntu2_amd64

名称

       chgpasswd - 批量更新组密码

大纲


       chgpasswd [options]

描述

       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:

       group_name:password

       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.

       此命令一般用于需要一次创建很多用户的大型系统。

选项

       The options which apply to the chgpasswd command are:

       -c, --crypt-method
           使用指定的方法加密密码。

           The available methods are DES, MD5, SHA256, SHA512, YESCRYPT and NONE if your libc supports these
           methods.

       -e, --encrypted
           提供的密码是已经加密了的

       -h, --help
           显示帮助信息并退出。

       -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. Only absolute paths are supported.

       -s, --sha-rounds
           使用指定次数的轮转来加密密码。

           You can only use this option with crypt method: SHA256 SHA512 YESCRYPT

           By default, the number of rounds for SHA256 or SHA512 is defined by the SHA_CRYPT_MIN_ROUNDS and
           SHA_CRYPT_MAX_ROUNDS variables in /etc/login.defs.

           A minimal value of 1000 and a maximal value of 999,999,999 will be enforced for SHA256 and SHA512.
           The default number of rounds is 5000.

           By default, the number of rounds for YESCRYPT is defined by the YESCRYPT_COST_FACTOR in
           /etc/login.defs.

           A minimal value of 1 and a maximal value of 11 will be enforced for YESCRYPT. The default number of
           rounds is 5.

CAVEATS

       记住要设置权限或者掩码来阻止其它用户对未加密文件的读取。

       您需要确保你吗和加密方法符合系统的密码策略。

配置文件

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

ENCRYPT_METHOD (string)
This defines the system default encryption algorithm for encrypting passwords (if no algorithm are
specified on the command line).

It can take one of these values: DES (default), MD5, SHA256, SHA512, YESCRYPT. MD5 and DES should not
be used for new hashes, see crypt(5) for recommendations.

Note: this parameter overrides the MD5_CRYPT_ENAB variable.

Note: This only affect the generation of group passwords. The generation of user passwords is done by
PAM and subject to the PAM configuration. It is recommended to set this variable consistently with
the PAM configuration.

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.

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.

SHA_CRYPT_MIN_ROUNDS (number), SHA_CRYPT_MAX_ROUNDS (number)
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).

With a lot of rounds, it is more difficult to brute force the password. But note also that more CPU
resources will be needed to authenticate users.

If not specified, the libc will choose the default number of rounds (5000), which is orders of
magnitude too low for modern hardware.

The values must be inside the 1000-999,999,999 range.

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.

YESCRYPT_COST_FACTOR (number)
When ENCRYPT_METHOD is set to YESCRYPT, this defines the cost factor used by the encryption algorithm
by default (when the cost factor is not specified on the command line).

With a high cost factor, it is more difficult to brute force the password. But note also that more
CPU resources will be needed to authenticate users.

The value must be inside the 1-11 range.

文件

       /etc/group
           组账户信息。

       /etc/gshadow
           安全组账户信息。

       /etc/login.defs
           Shadow 密码套件配置。

参见

       gpasswd(1), groupadd(8), login.defs(5).

shadow-utils 4.17.4                                2025-09-06                                       CHGPASSWD(8)