User Modification Commands in *nix

gistfile1.sh

# Add a user
$ sudo adduser ${user}

# Remove a user
$ sudo deluser ${user}

# Modify the users group
# ${group} is a comma separated list of groups without spaces, e.g. 'group1,group2,group3'
$ sudo usermod -G ${group} ${user}

# Modify the users password
$ sudo usermod -p ${user}