user_name:password
By default the passwords must be supplied in clear-text, and are encrypted by chpasswd. Also the password age will be updated, if present.
By default, passwords are encrypted by PAM, but (even if not recommended) you can select a different encryption method with the -e, -m, or -c options.
Except when PAM is used to encrypt the passwords, chpasswd first updates all the passwords in memory, and then commits all the changes to disk if no errors occurred for any user.
When PAM is used to encrypt the passwords (and update the passwords in the system database) then if a password cannot be updated chpasswd continues updating the passwords of the next users, and will return an error code on exit.
The options which apply to the chpasswd command are:
-c, --crypt-method 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。
默认,使用 PAM 来加密密码。
-e, --encrypted
-h, --help
-m, --md5
-R, --root CHROOT_DIR
-s, --sha-rounds 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:
/etc/passwd
/etc/shadow
/etc/login.defs
/etc/pam.d/chpasswd
passwd(1), newusers(8), login.defs(5), useradd(8).