Get GitHub Gist

gist-go

#!/bin/bash
#
# gist-go - Get a Github Gist
# Copyright (c) 2019 Alejandro Martinez Ruiz <alex flawedcode org>
#
# Downloads latest version of files in a Github gist, optionally outputting them to stdout.
# Files will by default be written to the current working directory, unless you
# specify --stdout (or -o) as first parameter.
#
# Usage:
#
# gist-go [--stdout|-o] <gist url> [<file_regexp>]
#
# 1st param: gist URL (where all files in the gist are listed)
# 2nd param (optional): Perl regexp that urls should match to be fetched, typically used for "globs".
#
# Example:
#
# * Show all Markdown (*.md) files from a gist in the terminal
# gist-go --stdout https://gist.github.com/unleashed/123abc \\.md$
#
# * Use gist-go with curl to execute a specific script
# curl -sSfL https://bit.ly/gist-go https://gist.github.com/unleashed/123abc script\\.sh$ | bash -s -- some-param
#
# TODO: (maybe?) sanitize file names to be included in grep as literals instead of grep expressions

GIST_BASE_URL="https://gist.github.com"

fetch_gist_paths()
{
    local gist_url="${1}"

    curl -sSfL "${gist_url}" | grep "<a .*>Raw</a>" | sed -E -e "s/.*\bhref=\"([^\"]*)\".*/\1/"
}

file_match_re()
{
    local path_re="${1}"
    local path="${2}"
    
    echo "${path}" | grep -P "${path_re}"
}

file_match()
{
    local file_re="${1}"
    local paths="${2}"
    
    for p in ${paths}; do
        file_match_re "${file_re}" "${p}"
    done
}

file_urls()
{
    local gist_url="${1}"
    local paths="${2}"
    local urls

    for p in ${paths}; do
        urls="${urls:+${urls} }${GIST_BASE_URL}${p}"
    done

    echo "${urls}"
}

gist_urls_for()
{
    local gist_url="${1}"
    local files="${@:2}"
    local paths="$(fetch_gist_paths "${gist_url}")"
    local urls="$(file_urls "${gist_url}" "${paths}")"
    local result

    if test "x${files}" = "x"; then
        result=${urls}
    else
        for f in ${files}; do
            for u in ${urls}; do
                thismatch="$(file_match "${f}" ${u})"
                if test "x${thismatch}" != "x"; then
                    result="${result:+${result} }${thismatch}"
                fi
            done
        done
    fi

    echo ${result}
}

go_gist()
{
    local stdout="${1}"

    if test "x${stdout}" != "x--stdout" -a "x${stdout}" != "x-o"; then
        curl_out="-O "
    else
        curl_opts="sf"
        shift
    fi
    
    local urls=$(gist_urls_for "${@}")
    local cmdline
    for u in ${urls}; do
        cmdline="${cmdline:+${cmdline} }${curl_out}${u}"
    done

    curl -${curl_opts}SL ${cmdline}
}

if test "x${BASH_SOURCE[0]}" = "x" -o "${BASH_SOURCE[0]}" = "${0}"; then
    set -eo pipefail
    shopt -s failglob

    go_gist "${@}"
fi