Script to check a text file of DOIs (one per line with Unix EOLs) against the Crossref API

crossref_doi_checker.php

<?php
# @name: crossref_doi_checker.php
# @version: 0.1
# @license: The MIT License (MIT) <https://mit-license.org/>
# @purpose: Checks a single text file of DOIs (one per line with Unix EOLs) against the Crossref API. 
# Run as 'php crossref_doi_checker.php '$doi_file'' e.g. 'php crossref_doi_checker.php doi_file.txt'
# @author: Simon Bowie <[email protected]>
# @acknowledgements: 
# https://github.com/CrossRef/rest-api-doc
?>

<?php
# PHP to define variables
    $apiurl="https://api.crossref.org/works/";
	$doi_file = $argv[1];
	#$doi = $argv[1];

	$handle = fopen($doi_file, "r");
	if ($handle) {
		while (($line = fgets($handle)) !== false) {
			$line = str_replace("\n", '', $line);
			# submit via cURL to Crossref's 'works' function in the API
			$ch = curl_init(); 
			$url = $apiurl;
			$queryParams = $line . '/';
			curl_setopt($ch, CURLOPT_URL, $url . $queryParams); 
			#curl_setopt($ch, CURLOPT_HEADER, TRUE); 
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
			$response = curl_exec($ch); 
			#$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE); 
			curl_close($ch); 
	
			$json_item = json_decode($response);
			$title = $json_item->message->title[0];
			$issn = $json_item->message->ISSN[0];
			echo "$title\n";
			echo "$issn\n";
   		}
    	fclose($handle);
	}
	else {
		// error opening the file.
	}
?>