How is a user created?
/etc/passwd user account information
/etc/shadow security user account information
/etc/group group account information
/etc/gshadow security group account information
/The default value when the etc/default/useradd account is created. (the default value in this file will be used when no parameter is specified)
[root@python ~]# cat /etc/default/useradd # useradd defaults file GROUP=100 # Default group HOME=/home # Default home directory INACTIVE=-1 # Enable expiration or not EXPIRE= # Expiration time SHELL=/bin/bash # Default shell SKEL=/etc/skel # The default files in the home folder are copied from here. CREATE_MAIL_SPOOL=yes # Do you want to create a mailbox for users
/etc/skel directory containing default files
[root@python skel]# ll -a //Total consumption 24 drwxr-xr-x. 3 root root 78 4 month 11 2018 . drwxr-xr-x. 149 root root 8192 7 month 2 19:35 .. -rw-r--r--. 1 root root 18 10 month 31 2018 .bash_logout -rw-r--r--. 1 root root 193 10 month 31 2018 .bash_profile -rw-r--r--. 1 root root 231 10 month 31 2018 .bashrc drwxr-xr-x. 4 root root 39 5 month 16 05:24 .mozilla
/etc/login.defs-Shadow Password Suite configuration.
[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
The creation of users depends on these files.
Common things...