Unix add user implementation
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$ ./adduser -h
usage: adduser [options] username
options -
--skeleton DIR specify the skeleton directory (default: /etc/skel)
--home DIR specify the home directory (default: /home)
username name of valid user login on system
$ ./adduser john
ERROR: cannot add user, must be administrator
$ sudo ./adduser john
Enter password:
Re-enter password:
User john successfully created!
$ sudo ./adduser --skeleton /etc/skels john
# creating user john using the /etc/skels to create home directory
$ sudo ./adduser --skeleton /etc/kels john
ERROR: '/etc/kels' directory not found
$ sudo ./adduser john
ERROR: 'john' already exists
$ sudo ./adduser --home /test john
ERROR: '/test' directory not found
$ sudo ./adduser --home /var/www john
# creating user john with /var/www/john as the default home directory
- Check if user running the script has root access.
- Check if the given username already exists or not.
- Check the validity of the username
[a-z_][a-z0-9_-]*$. (Can contain only lowercase alphanumeric with underscore and dash, cannot start with anything other than a lowercase alphabet or an underscore) - Find the next available user and group ID using the passwd database.
- Ask for password, use python and the crypt library to encrypt password based on
/etc/login.defsENCRYPT_METHOD - Update the
/etc/passwd,/etc/group,/etc/gshadowand/etc/shadowfiles. (/etc/shadowdoesn't need to be updated is using thepasswdcommand) - Copy files from the skeleton directory to the new user's home directory and create a mail spool file.
- Set permissions on the home directory.
- Use
/etc/login.defsto find different configurations for creating mail spool file, UID, GID and encryption method. - After updating
/etc/passwdwith the record,passwd usernamecommand can be run to set the password for username for default unix system password setup instead of using the python script to encrypt password manually.