一个用户，到底是怎么被创建出来的呢？
/etc/passwd 用户账户信息
/etc/shadow 安全用户账户信息
/etc/group 组账户信息
/etc/gshadow 安全组账户信息
/etc/default/useradd 账户创建时的默认值。(不指定参数时就会使用这个文件中的默认值)
[root@python ~]# cat /etc/default/useradd # useradd defaults file GROUP=100 # 默认组 HOME=/home # 默认家目录 INACTIVE=-1 # 是否启用过期 EXPIRE= # 过期的时间 SHELL=/bin/bash # 默认的shell SKEL=/etc/skel # 默认的home文件夹中默认的文件 从这里拷贝的 CREATE_MAIL_SPOOL=yes # 要不要给用户创建邮箱
/etc/skel 包含默认文件的目录
[root@python skel]# ll -a 总用量 24 drwxr-xr-x. 3 root root 78 4月 11 2018 . drwxr-xr-x. 149 root root 8192 7月 2 19:35 .. -rw-r--r--. 1 root root 18 10月 31 2018 .bash_logout -rw-r--r--. 1 root root 193 10月 31 2018 .bash_profile -rw-r--r--. 1 root root 231 10月 31 2018 .bashrc drwxr-xr-x. 4 root root 39 5月 16 05:24 .mozilla
/etc/login.defs Shadow 密码套件配置。
[root@python ~]# cat /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
用户的创建就是，依靠这些文件进行创建的。
常用的东西。。。
作业：
创建三个用户 harry tom natasha
要求harry tom 附加到admin 组
natasha 不允许登录
修改默认创建用户环境：
要求用户家目录为 /home
uid， gid 从1000开始
登录shell 为 /bin/csh
要求：
使用 useradd a
创建 a 的家目录为/rhome/a uid 100 gid 1000 shell:/bin/csh