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October 1, 2023 16:40
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Save Raiu/23418eac4e78856167121b4f02c13db7 to your computer and use it in GitHub Desktop.
This script automatically adds SSH keys from a GitHub user to the authorized_keys file on a local machine while keeping all manually added keys.
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| #!/usr/bin/env sh | |
| : ' | |
| This script helps you download your ssh keys from Github while keeping any existing keys. | |
| Usage: | |
| ./add_github_keys.sh [OPTIONS] USERNAME | |
| Without downloading: | |
| curl -fsSL https://gist.githubusercontent.com/Raiu/23418eac4e78856167121b4f02c13db7/raw | sh -s -- USERNAME | |
| Options: | |
| -c, --comment COMMENT Identifier for GH keys (default: GH-Key) [optional] | |
| -p, --path PATH Path to authorized_keys (default: ~/.ssh/authorized_keys) [optional] | |
| -h, --help Show this help message and exit | |
| ' | |
| _exist() { command -v "$@" >/dev/null 2>&1; } | |
| ! _exist 'curl' && printf 'Install: curl' && exit 1 | |
| ! _exist 'ssh-keygen' && printf 'Install: ssh-keygen' && exit 1 | |
| # Set default values | |
| key_comment="GH-Key" | |
| auth_keys="${HOME}/.ssh/authorized_keys" | |
| # Verify and validate SSH keys function | |
| verify_key() { | |
| printf '%s\n' "$1" | ssh-keygen -l -f - > /dev/null 2>&1 | |
| } | |
| # Verify Github username function | |
| verify_username() { | |
| printf '%s\n' "$1" | grep -qE '^[a-zA-Z0-9]([-a-zA-Z0-9]{0,37}[a-zA-Z0-9])?$' | |
| } | |
| # Validate option has an argument | |
| validate_option() { | |
| if [ -z "$2" ] || [ "${2#-}" != "$2" ]; then | |
| printf 'Error: option requires an argument -- %s\n' "$1" >&2 | |
| help >&2 | |
| exit 1 | |
| fi | |
| } | |
| # Help function | |
| help() { | |
| cat <<EOF | |
| Usage: ${0##*/} [options] <username> | |
| Options: | |
| -c, --comment <comment> Set comment for the key (default: GH-Key) | |
| -p, --path <path> Set path to authorized_keys file (default: ~/.ssh/authorized_keys) | |
| -h, --help Show this help message and exit | |
| EOF | |
| } | |
| # Parse arguments | |
| while [ $# -gt 0 ]; do | |
| case "$1" in | |
| -c|--comment) | |
| validate_option "$@" | |
| key_comment="$2" | |
| shift 2 | |
| ;; | |
| -p|--path) | |
| validate_option "$@" | |
| auth_keys="$2" | |
| shift 2 | |
| ;; | |
| -h|--help) | |
| help | |
| exit 0 | |
| ;; | |
| -*) | |
| printf 'Error: unrecognized option -- %s\n' "$1" >&2 | |
| help >&2 | |
| exit 1 | |
| ;; | |
| *) | |
| break | |
| ;; | |
| esac | |
| done | |
| # Verify username | |
| ! verify_username "$1" && printf '%s is not a valid username\n' "$1" && help && exit 1 | |
| username=$1 | |
| # Create authorized_keys file if it doesn't exist and set correct permissions. | |
| if [ ! -f "${auth_keys}" ]; then | |
| mkdir -p "${auth_keys%/*}" | |
| chmod 700 "${auth_keys%/*}" | |
| touch "${auth_keys}" | |
| chmod 600 "${auth_keys}" | |
| fi | |
| # Read content from authorized_keys into a temporary file. | |
| temp_file=$(mktemp) | |
| while read -r line; do | |
| if ! printf '%s\n' "${line}" | grep -q "${key_comment}$"; then | |
| if verify_key "${line}"; then | |
| printf '%s\n' "${line}" >> "${temp_file}" | |
| fi | |
| fi | |
| done < "${auth_keys}" | |
| # try to grab ssh keys from GH | |
| printf '\n# Github keys\n' >> "${temp_file}" | |
| curl -s "https://github.com/${username}.keys" | while read -r key; do | |
| if verify_key "${key}"; then | |
| printf '%s %s\n' "${key}" "${key_comment}" >> "${temp_file}" | |
| fi | |
| done | |
| # If the old file and new file is the same, skip writing. | |
| if ! cmp "${temp_file}" "${auth_keys}" > /dev/null 2>&1; then | |
| cat "${temp_file}" > "${auth_keys}" | |
| fi | |
| rm "${temp_file}" |
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