thoughts/src/rss.sh

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#!/bin/bash
# Generate RSS feed from given post metadata files
#
# Copyright (C) 2019 Mike Gerwitz
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# All posts must be provided on the command line as a path to each
# individual metadata file, in the order in which they should appear in the
# feed output.
##
set -euo pipefail
# Website root URL.
declare -r www=${WWW_URL:-https://mikegerwitz.com}
# Look up metadatum FIELD in metafile FILE.
pmeta()
{
local -r file=${1?Missing metafile name}
local -r field=${2?Missing field name}
recsel -P "$field" "$file"
}
# Generate RSS item for each post in provided arguments.
# See `gen-item'.
gen-items()
{
while [ $# -gt 0 ]; do
gen-item "$1"
shift
done
}
# Generate RSS item for post in metadata file FILE. The abstract will be
# used for the item description.
gen-item()
{
local -r file=${1?Missing file name}
local subject author slug date
subject=$( pmeta "$file" subject )
author=$( pmeta "$file" author )
slug=$( pmeta "$file" slug )
date=$( pmeta "$file" date )
# TODO: entire content?
local abstract
abstract=$( pmeta "$file" abstract )
cat <<EOF
<item>
<title><![CDATA[$subject]]></title>
<author><![CDATA[$author]]></author>
<link>$www/$slug</link>
<pubDate>$date</pubDate>
<description><![CDATA[
$abstract
<p><a href="$www/$slug">(Read full post)</a></p>
]]></description>
</item>
EOF
}
# Output usage information and exit with EX_USAGE.
usage()
{
cat <<EOF
Usage: $0 postmeta...
Generate RSS feed from provide post metadata.
Example: $0 post/2018-01-01-foo.meta post/2018-02-01-bar.meta
At least one postmeta must be provided.
EOF
exit 64 # EX_USAGE
}
# Output RSS feed from all post files provide via arguments.
main()
{
test $# -gt 0 || usage
cat <<EOF
<?xml version="1.0"?>
<rss version="2.0">
<channel>
<title>Mike Gerwitz's Thoughts and Ramblings</title>
<link>$www</link>
<description>
Posts and articles from a free software hacker and activst with a focus on user privacy and security
</description>
$( gen-items "$@" )
</channel>
</rss>
EOF
}
main "$@"