chpasswd(8)

CHPASSWD(8)

System Management Commands

CHPASSWD(8)

NAME

chpasswd - update passwords in batch mode

SYNOPSIS

chpasswd [options]

DESCRIPTION

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

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.

This command is intended to be used in a large system environment where many accounts are created at a single time.

OPTIONS

The options which apply to the chpasswd command are:

-c, --crypt-method METHOD

Use the specified method to encrypt the passwords.

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

By default, PAM is used to encrypt the passwords.

-e, --encrypted

Supplied passwords are in encrypted form.

-h, --help

Display help message and exit.

-m, --md5

Use MD5 encryption instead of DES when the supplied passwords are not encrypted.

-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.

-P, --prefix PREFIX_DIR

Apply changes to configuration files under the root filesystem found under the directory PREFIX_DIR. This option does not chroot and is intended for preparing a cross-compilation target. Some limitations: NIS and LDAP users/groups are not verified. PAM authentication is using the host files. No SELINUX support.

CAVEATS

Remember to set permissions or umask to prevent readability of unencrypted files by other users.

CONFIGURATION

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

FILES

/etc/passwd

User account information.

/etc/shadow

Secure user account information.

/etc/login.defs

Shadow password suite configuration.

/etc/pam.d/chpasswd

PAM configuration for chpasswd.