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#!/usr/bin/env bash
#
# @license Apache-2.0
#
# Copyright (c) 2017 The Stdlib Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Download a remote resource.
#
# Usage: download <url> [output_filepath]
#
# Arguments:
#
# url Remote resource.
# output_filepath Output filepath.
#
# VARIABLES #
# Set the url:
url="$1"
# Find a program for downloading a resource:
CURL=$(command -v curl 2>/dev/null)
WGET=$(command -v wget 2>/dev/null)
FETCH=$(command -v fetch 2>/dev/null)
# Define a timeout (in seconds):
timeout=30
# Define command options:
curl_opts="-fkL --connect-timeout ${timeout} -y ${timeout}"
wget_opts="--no-check-certificate --tries=1 --timeout=${timeout}"
fetch_opts="-T ${timeout}"
# FUNCTIONS #
# Prints usage information.
usage() {
echo '' >&2
echo 'Usage: download <url> [output_filepath]' >&2
echo '' >&2
}
# MAIN #
# Handle arguments...
if [[ "$#" -eq 0 ]]; then
usage
exit 0
elif [[ "$#" -eq 1 ]]; then
curl_opts="${curl_opts} -O"
elif [[ "$#" -eq 2 ]]; then
curl_opts="${curl_opts} -o $2"
wget_opts="${wget_opts} -O $2"
fetch_opts="${fetch_opts} -o $2"
else
echo 'ERROR: unrecognized arguments. Must provide a URL and, optionally, an output filepath.' >&2
exit 1
fi
# Determine the command for downloading a resource...
if [[ -x "${CURL}" ]] && "${CURL}" -V >/dev/null; then
get="${CURL}"
opts="${curl_opts}"
elif [[ -x "${WGET}" ]] && "${WGET}" -V >/dev/null; then
get="${WGET}"
opts="${wget_opts}"
elif [[ -x "${FETCH}" ]]; then
get="${FETCH}"
opts="${fetch_opts}"
else
echo 'ERROR: missing dependency. Please download either curl, wget, or fetch. Once installed, run the command again.' >&2
exit 1
fi
# Download the resource:
eval "${get} ${opts} ${url}"
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