Import SSH keys from github with a simple bash script

import-github-sshkey.sh

#!/bin/bash
set -eu

if ! which jq >/dev/null && which curl >dev/null; then
	echo "Installing dependencies!"
	/usr/bin/pacman -Syu --noconfirm curl jq
fi

if (( $# != 2 )); then
	echo "Import ssh public keys from github user to authorized_keys"
	echo "of local user on this system."
	echo ""
	echo "usage: $0 <system_user> <github_user>"
	exit -1
fi

SYS_USER="$1"
GITHUB_USER="$2"

if ! id -u "$SYS_USER"; then
	echo "No such user on system: '$SYS_USER'"
	exit 2
fi

USER_HOME=$(getent passwd "$SYS_USER" | cut -d ":" -f6)
SSH_PATH="$USER_HOME/.ssh/"
AUTHORIZED_KEYS="$SSH_PATH/authorized_keys"

mkdir -p $SSH_PATH
chmod 700 $SSH_PATH
chown $SYS_USER $SSH_PATH

if /usr/bin/curl -L "http://api.github.com/users/$GITHUB_USER/keys" \
    | /usr/bin/jq -r '.[].key' \
    > "/tmp/github_keys_$GITHUB_USER"
then
    echo "SUCCESS: added keys from github user $GITHUB_USER"
    echo "# github ssh-keys for github user $GITHUB_USER" >> "$AUTHORIZED_KEYS"
    cat "/tmp/github_keys_$GITHUB_USER" >> "$AUTHORIZED_KEYS"
    chmod 600 "$AUTHORIZED_KEYS"
    chown "$SYS_USER" "$AUTHORIZED_KEYS"
    exit 0
else
    echo "WARNING: failed to fetch ssh public keys from GH"
    exit 1
fi