/etc/login.defs 是设置用户帐号限制的文件。该文件里的配置对root用户无效。优先级低于/etc/shadow里面的配置。
使用vim打开文件
[root@localhost ~]# vim /etc/login.defs
#
# Please note that the parameters in this configuration file control the
# behavior of the tools from the shadow-utils component. None of these
# tools uses the PAM mechanism, and the utilities that use PAM (such as the
# passwd command) should therefore be configured elsewhere. Refer to
# /etc/pam.d/system-auth for more information.
#
# *REQUIRED*
# Directory where mailboxes reside, _or_ name of file, relative to the
# home directory. If you _do_ define both, MAIL_DIR takes precedence.
# QMAIL_DIR is for Qmail
#
#QMAIL_DIR Maildir
MAIL_DIR /var/spool/mail
#MAIL_FILE .mail
# Password aging controls:
#
# PASS_MAX_DAYS Maximum number of days a password may be used.
# PASS_MIN_DAYS Minimum number of days allowed between password changes.
# PASS_MIN_LEN Minimum acceptable password length.
# PASS_WARN_AGE Number of days warning given before a password expires.
#
PASS_MAX_DAYS 99999
PASS_MIN_DAYS 0
PASS_MIN_LEN 5
PASS_WARN_AGE 7
#
# Min/max values for automatic uid selection in useradd
#
UID_MIN 1000
UID_MAX 60000
# System accounts
SYS_UID_MIN 201
SYS_UID_MAX 999
#
# Min/max values for automatic gid selection in groupadd
#
GID_MIN 1000
GID_MAX 60000
# System accounts
SYS_GID_MIN 201
SYS_GID_MAX 999
#
# If defined, this command is run when removing a user.
# It should remove any at/cron/print jobs etc. owned by
# the user to be removed (passed as the first argument).
#
#USERDEL_CMD /usr/sbin/userdel_local
#
# If useradd should create home directories for users by default
# On RH systems, we do. This option is overridden with the -m flag on
# useradd command line.
#
CREATE_HOME yes
# The permission mask is initialized to this value. If not specified,
# the permission mask will be initialized to 022.
UMASK 077
# This enables userdel to remove user groups if no members exist.
#
USERGROUPS_ENAB yes
# Use SHA512 to encrypt password.
ENCRYPT_METHOD SHA512
删除注释信息后
#创建用户时，要在目录/var/spool/mail中创建一个用户mail文件
MAIL_DIR /var/spool/mail
#密码最大有效期99999
PASS_MAX_DAYS 99999
#两次修改密码的最小间隔时间0
PASS_MIN_DAYS 0
#密码最小长度，对于root无效
PASS_MIN_LEN 5
#密码过期前多少天开始提示
PASS_WARN_AGE 7
#创建用户时不指定UID的话自动UID的范围
UID_MIN 1000
#用户ID的最小值
UID_MAX 60000
#系统uid的最小值
SYS_UID_MIN 201
#系统uid的最大值
SYS_UID_MAX 999
#用户组GID的最小值
GID_MIN 1000
#用户组GID的最大值
GID_MAX 60000
#系统用户组GID的最小值
SYS_GID_MIN 201
#系统用户组GID的最大值
SYS_GID_MAX 999
#允许使用useradd的时候创建用户家目录
CREATE_HOME yes
#权限掩码设置为077（默认为022，注释里面有这方面介绍）
UMASK 077
#使用命令 userdel 删除用户时，是否删除用户的初始组，默认是删除
USERGROUPS_ENAB yes
#指定 Linux 用户的密码使用 SHA512 散列模式加密，这是新的密码加密模式，原先的 Linux只能用 DES 或 MD5 方式加密
ENCRYPT_METHOD SHA512