Manage who can do what on the system.


create user

Either useradd or adduser

$ sudo adduser -m <name>   # create user + home dir

# now it's time to make the user the owner of the home dir,
# and set the right permissions for all files within.

$ chown <user>:<user> -R ~/<user>      # recursively change owner
$ chmod 700 /home/<user>               # hide dir from other users
$ chsh -s /usr/local/bin/bash <user>   # change login shell

or alternatively:

$ sudo adduser -m <user>  # does all of the above in a single command except


Groups have combined settings; individual users can be added to groups which then inherit the permissions of the group.

create group

$ groupadd <name>

add user to group

$ sudo usermod -G <group> <user>
$ sudo usermod -a -G docker ec2-user

add hostname to /etc/hosts

Sometime a 'host not found' error pops up. This means that the host is not in the hostfile. This is a common error on remote servers. In order to add the ip, create a mapping such as: localhost  # alias localhost to


edit password

# opens interactive session
$ sudo passwd <user>



default dir permissions

$ chmod 07555

give specific user permissions for dir

# change owner
$ sudo chmod <username>: <dirname>

# give write permissions
$ sudo chmod u+w <dirname>
# add user to group associated with directory
$ sudo usermod -a -G <groupname> <username>

# give group write permissions
$ sudo chmod g+w <dirname>

Change user

# possibly prepend with "sudo"
$ su - <username>
$ whoami
# => <username>

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