Strange regular expression warning

LeeC79 has asked for the wisdom of the Perl Monks concerning the following question:

I've written a simple script that searches a directory for a file with a certain extension. The script then does *stuff* with those files. It runs fine on my machine, but we've recently scheduled the script to run on our server and it fails. Here's the code:

opendir DIR, $dir;
my @file = grep {/^*.ORD_API_log$/} readdir DIR;
closedir DIR;
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Here's the error we get on our server:

{/^*.ORD_API_log$/: regexp *+ operand could be empty at ....
[download]

Just looking for what that error means. Thanks. _{janitored by ybiC: Retitle from less-than-descriptive "What's Wrong?" for better site search results}

Comment on Strange regular expression warning Select or Download Code

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Re: Strange regular expression warning by gellyfish (Monsignor) on Jul 15, 2004 at 14:39 UTC
It means you have an old version of Perl , I mean really old like Perl 4 , on the server. I would recommend upgrading the Perl or using a more recent one if available but swapping round the . to . in your regular expression will fix it. /J\	[reply]
Re^2: Strange regular expression warning by Joost (Canon) on Jul 15, 2004 at 15:31 UTC
As far as I can make out by googling, this message is emitted by 5.00404 (don't know about older/newer versions, except that it's not in perldiag for 5.8.5) edit: that still means you should probably upgrade the perl on the server (or install a newer version next to it) "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re^2: Strange regular expression warning by Roy Johnson (Monsignor) on Jul 15, 2004 at 15:17 UTC
perl4 wouldn't take a block as an operand to grep. We're not really tightening our belts, it just feels that way because we're getting fatter.	[reply]
Re: Strange regular expression warning by elusion (Curate) on Jul 15, 2004 at 15:31 UTC
From the looks of things, I believe (meaning this is untested) the reason you're getting this error is because `` has a special meaning inside of a regex. It denotes the previous character as something that may occur zero or more times. Unfortunately, your's is empty -- it doesn't have anything to match. (Maybe your `.` is in the wrong order?) Try putting something in front: `/^.\.ORD_API_log$/` That would matching anything that ended in `.ORD_API_log`. Of course, as someone else mentioned, it'd be easier to check the end and just forget about the beginning: `/\.ORD_API_log$/` Hope this helps, elusion* : http://matt.diephouse.com	[reply] [d/l] [select]
Re: Strange regular expression warning by delirium (Chaplain) on Jul 15, 2004 at 15:23 UTC
I'll comment on the regex: If you are interested in how the filename ends, you don't need to worry about how it starts. Try using: `/\.ORD_API_log$/` ...which doesn't root the match to the beginning of the string (and explicitly looks for a period before the extension).	[reply] [d/l]