Perl: test if remote file exists http

Question

Hello Everyone!

I need to test if a remote file on a http server exists without downloading it. I looked into various command line programs like wget, curl, axel, but could not find a test-only flag.

I am working in an production environment and only have a limitations on modules I can work with. Looking around, the LWP::Simple->head() function seems suitable, but returns undef when trying it:

#!/usr/bin/perl -w
use strict;
use LWP::Simple;

  my $url = 
'http://hgdownload.cse.ucsc.edu/goldenPath/hg18/encodeDCC/wgEncodeUwChIPSeq/wgEncodeUwChIPSeqAlignmentsBjInput.tagAlign.gz';

 my $head = LWP::Simple->head($url);
 #my $head = head($url);

 print "$head\n";

Any pointers greatly appreciated!

Thanks, Thomas

score 3 · Accepted Answer · answered Jul 12 '12 at 09:36

3

head is an exported function, not a class method. You are invoking it wrong.

use LWP::Simple qw(head);

my $url = …
if (head($url)) {
    # sucess
} else {
    # no success
}

# alternatively skip the import, supply fully qualified function name:
# use LWP::Simple qw();
# if (LWP::Simple::head($url)) …

answered Jul 12 '12 at 09:36

daxim

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Thanks daxim, that solved part. Now it returns false all the time. I also tried fetching index pages from 2 other sites, still always false. Any ideas about that? – juettemann Jul 12 '12 at 10:06
Ok, it seems to be an issue with the proxy config, nothing wrong with LWP. – juettemann Jul 12 '12 at 10:19

Perl: test if remote file exists http

1 Answers1