Friday, May 18, 2012

Cycle through all files in a subdirectory

I recently signed up for the perl Ironman challenge at  I've had this blog sitting around for a long time (maybe 7 years) but never posted to it.  I've been using my blog "The Red Stallion Patrol" for all my posts, but wanted to separate out my perls of wisdom.  This is a cross post of an item I posted 4 days ago.

Here's the code I use to cycle through all the files in a sub-directory, make sure they exist and have a non-zero size. If this all passes, process the file.  I use this pretty frequently at work to do "something interesting" with all files in a sub-directory (folder to you windows users) that may contain any number of files (probably added to daily) of a certain type.


use warnings;
use strict;

my $DIR = "/some/directory";
my $inputfile = $ARGV[0];

# ----- Go through all the files in a directory
my $InputDir = join("/", $DIR, $inputfile);
opendir (ARCHIVE, $InputDir ) or die "can't opendir ARCHIVE $InputDir: $!";
my @InputDirFiles = grep { -f }                               # select files only
                    map { "$InputDir/$_" }                    # IMPORTANT - prepend directory name
                    grep { ( $_ ne '.' ) and ( $_ ne '..' ) } # throw out dots entries
                    readdir ARCHIVE;
closedir ( ARCHIVE ) or warn "can't closedir ARCHIVE: $!";

local $, = "\n";

foreach my $CurrentFile (@InputDirFiles) {
    # ----- Does the file exist?
    (my $dev,my $ino,my $mode,my $nlink,my $uid,my $gid,my $rdev,my $size,my $atime,my $mtime,my $ctime,my $blksize,my $blocks)
            = stat("$CurrentFile");

    if (-e _) {
        printf "\t$CurrentFile exists.\n";
        if (-z _) {
            printf "\t\tIt is zero bytes\n";
        if (-s _) {
            printf "\t\tIt is $size bytes long\n";
            # ----- at this point the file exists and has size.
            #       you could open it and have your way with it.
    } else {
        printf "\tDidn't find $CurrentFile\n";

    # ----- You could also wait until this point to
    #       open it and have your way with it.

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