Unix Users and Groups

Users

CRUD

Just see:

Chris Fidao's article on SFH: http://serversforhackers.com/editions/2014/05/06/permissions-users/

http://www.cyberciti.biz/faq/howto-add-new-linux-user-account/

http://www.cyberciti.biz/faq/howto-linux-add-user-use-adduser-command/

Adding a User

$ groupadd george
$ useradd -d /home/george -g george -s /bin/bash george
$ mkdir /home/george
$ chown george:george /home/george

Adding a User Without a Home Directory

$ groupadd george
$ useradd -M -g george -s /bin/false george

Adding an FTP-Only User

Replace "ftp" with whatever you want to call the user:

$ useradd -d /home/ftp -g ftp -s /bin/false ftp

Article on using /bin/false:

http://www.semicomplete.com/articles/ssh-security/

http://www.cyberciti.biz/tips/linux-prevent-normal-users-from-logging-into-system.html

Add a User to a Group

$ usermod -a -G wheel george

http://www.cyberciti.biz/faq/howto-linux-add-user-to-group/

Adding a Sudoer

On most computers you only need to add the user to a group that is a sudoer group, i.e. the "wheel" and "sudo" groups are common. Here is one example:

$ adduser george sudo

http://linuxpoison.blogspot.com/2008/12/configuring-sudo-and-adding-users-to.html

Groups

CRUD

http://www.cyberciti.biz/faq/howto-linux-add-user-to-group/

http://www.cyberciti.biz/faq/unix-add-user-to-group/

Users and Groups on a Mac

For some unknown reason Macs do not have usermod. Instead, Macs use dscl. Here are some examples:

Users

Adding a User to a Group

Thank you user1256923, whoever you are, for posting how to do this on Stack Exchange:

$ dscl . append /Groups/wheel GroupMembership george

Where "wheel" is the group and "george" is the user. Note that this does not change the user's primary group.