read directory

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

How do you get the read directory function to sort by latest modified date???

Any advice? Thanks in advance.

use CGI ':standard';
use strict;
use CGI::Carp qw/fatalsToBrowser/;
use File::Spec::Functions;

opendir( FILES, "pending" ) || die "Cannot opendir /some/path: $!";

print "Content-type: text/html\n\n";

print "<TABLE BORDER=1>\n<TR><TH
align=left>Files</TH><TH
align=left>Last Modified On</TH>

</TR>";

my $files;
my $mod;

while ( $files = readdir(FILES) )
{

    $mod = ( stat( catfile( 'pending', $files ) ) )[9];
    $mod = localtime($mod);

    # href will have path to new cgi
    print "<TR><TD><a href=createhtml.cgi?filename=" . $files
        . ">$files</a></TD><TD>$mod</TD>
    </TR>";
}
print "</TABLE>";

closedir(FILES);

sub Error
{
    print "Content-type: text/html\n\n";
    print "The server can't $_[0] the $_[1]: $! \n";
    exit;
}
[download]

Comment on read directory Download Code

Replies are listed 'Best First'.
Re: read directory by jbisbee (Pilgrim) on Jul 08, 2006 at 01:08 UTC
Here is a quick example using glob, map, and sort to produce a list of files and their modified times. It's not quite a Swartzian transform, because we leave the modified time hanging around for the output. `#!/usr/bin/perl use strict; use warnings; use CGI qw(:standard); my %cache = (); my @files = sort { $b->[1] <=> $a->[1] } map { [ $_, (stat($_))[9] ] } glob('pending/'); print header; print "<table>\n"; for my $file (@files) { print "<tr><td>$file->[0]</td><td>" . localtime( $file->[1] ) . "</td></tr>\n"; } print "</table>\n";` [download] also in the future, put <code></code> around code you post* :) -biz-	[reply] [d/l]
Re: read directory by shmem (Chancellor) on Jul 08, 2006 at 10:49 UTC
You don't. readdir (and glob) return the entries in the order the OS kernel pleases to present them. You have to sort yourself: `@files = sort {-M $a <=> -M $b} <>; # update - better without -M in sort opendir(D,$dir); @files = map { $_->[1] } sort { $a->[0] <=> $b->[0] } map { [-M $_, $_] } grep {!/^\.\.?$/} readdir(D);` [download] A related thread is here. --shmem update:* added ST after reading TedPride's post ;-) _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l]
Re^2: read directory by jbisbee (Pilgrim) on Jul 08, 2006 at 14:12 UTC
Update: Sorry, I know this post was a bit lame and didn't prove anything I just benchmarked the difference between "glob" and "<>" and found very little difference (subsequent runs flip-flopped which was faster). If that's the case, then I'd prefer the glob('pending/') over the <pending/> call because of the awkward bare word. But then, thats just me. `#!/usr/bin/perl use strict; use warnings; use Benchmark qw(cmpthese); cmpthese( 20_000, { '<>' => sub { my @results = <pending/>; }, 'glob' => sub { my @results = glob('pending/'); }, }, );` [download] and the results `Rate glob <> glob 7194/s -- -0% <> 7220/s 0% --` [download] -biz-	[reply] [d/l] [select]
Re^3: read directory by shmem (Chancellor) on Jul 08, 2006 at 14:28 UTC
well, `<DATA>` also has a bareword.. ;-) I'm not surprised that `glob` and `<>` down differ much, since they are essentially the same... bigger savings can be achieved by using -M instead of `(stat)[9]`, because doing so eliminates the overhead of making a list just to get its 10^th element. --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l] [select]
Re^3: read directory by Hue-Bond (Priest) on Jul 08, 2006 at 14:33 UTC
I just benchmarked the difference between "glob" and "<>" and found very little difference That's hardly surprising since glob `is the internal function implementing the "<*.c>" operator` according to the documentation. -- David Serrano	[reply]
Re: read directory by TedPride (Priest) on Jul 08, 2006 at 20:07 UTC
It might be more efficient to call ls, if the number of files in the directory is large. You certainly don't want to call -M from inside a sort, as shmem suggests. my @files = split /\n/, `ls -1t`; for (@files) { ... } [download] The -1 modifier forces output to one column, and -t sorts by last time modified.	[reply] [d/l]


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