A tool to create a user and populate it's ssh authorized_keys file with their github public keys

create_user

#!/bin/bash

if [ "$#" -lt "1" ]; then
    echo "usage"
    echo "$0 GITHUB_USERNAME UNIX_USERNAME"
    echo "$0 GITHUB_AND_UNIX_USERNAME"
    echo "$0 GITHUB_USERNAME -G wheel UNIX_USERNAME"
    echo "$0 GITHUB_USERNAME --home /opt/foo -G wheel UNIX_USERNAME"
    exit 1
fi

github_username="$1"
shift

if [ "$*" = "" ]; then
    unix_username="$github_username"
    useradd_args="$unix_username"
else
    eval unix_username="\$$#"
    useradd_args="$*"
fi

if ! useradd $useradd_args; then
    echo "Useradd failed"
    exit 1
fi
users_home="`getent passwd "$unix_username" | cut -d: -f6`"

if [ ! -d "$users_home/.ssh" ]; then
    install --owner "$unix_username" --group `id --group "$unix_username"` --mode 700 --verbose --directory "$users_home/.ssh"
fi
if [ ! -e "$users_home/.ssh/authorized_keys" ]; then
    install --owner "$unix_username" --group `id --group "$unix_username"` --mode 600 --verbose /dev/null "$users_home/.ssh/authorized_keys"
fi

if pubkeys="`curl --fail https://github.com/$github_username.keys`"; then
    echo "$pubkeys" >>"$users_home/.ssh/authorized_keys"
    echo "User created and public keys loaded"
else
    echo "Failed to fetch keys at https://github.com/$unix_username.keys"
    echo "User $unix_username created but public keys were not loaded"
    exit 1
fi