Created
January 16, 2018 16:35
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#!/bin/bash | |
conditional_get_etag() { | |
local _url _file _tmpdir | |
local _awk_program='/^ETag:/ {$1=""; printf "If-None-Match: %s", substr($0, 2, length($0)-2); exit;}' | |
for _url; do | |
if [ '--file=' = "${_url:0:7}" ]; then | |
_file="${_url:7}" | |
continue | |
fi | |
if [ -z "$_file" ]; then | |
_tmpdir="$(mktemp -d --tmpdir .curl-filename-XXXXXX || { mkdir -p '.tmp' && echo '.tmp'; })" | |
fi | |
if [ -n "$_tmpdir" ] && cd "$_tmpdir"; then | |
# This is a guess, but doesn't hurt if we're wrong. | |
cp 2>/dev/null ~-/"$(basename "$_url").headers" '.headers' | |
curl > '.filename' -JLORSs -w '%{filename_effective}\n' -H "$(awk 2>/dev/null "$_awk_program" ".headers")" -D '.headers' "$_url" | |
_file="$( < .filename )" | |
[ -n "$_file" ] || _file="$(basename "$_url")" | |
if [ -s "$_file" ]; then | |
mv "$_file" ~-/"${_file}.tmp" && mv '.headers' ~-/"${_file}.tmp.headers" | |
fi | |
cd - >/dev/null | |
rm -rf "$_tmpdir" | |
else | |
curl -JLRSs -H "$(awk 2>/dev/null "$_awk_program" "${_file}.headers")" -D "${_file}.tmp.headers" -o "${_file}.tmp" "$_url" | |
fi | |
unset -v _tmpdir | |
if [ -s "${_file}.tmp" ]; then | |
[ ! -f "$_file" ] || chown -v --reference "$_file" "${_file}.tmp" | |
[ ! -f "$_file" ] || chmod -v --reference "$_file" "${_file}.tmp" | |
mv -v "${_file}.tmp" "$_file" | |
mv -v "${_file}.tmp.headers" "${_file}.headers" | |
fi | |
rm -f "${_file}.tmp.headers" "${_file}.tmp" | |
unset -v _file | |
done; unset -v _url | |
} | |
conditional_get_etag "$@" |
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