Willman023 has asked for the wisdom of the Perl Monks concerning the following question:

I have to get a script working by tomorrow afternoon that involves simply getting a file size,I've looked on the net, and I have 4 CGI/Perl books,but all I found was 
$size = -s "$filename";
and someone eluded to:
$size = (stat("$filename"))[7];

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but when I run this, and print out to file it's just blank between the parenthesis. print OUTFILE "($size)"; So is there any other way to get a file's size, and how come its blank and I don't get an error or some indication that something is wrong? Thanks so much!

Edit by dws to add <code> tags

Replies are listed 'Best First'.
Re: Getting file size
by Aristotle (Chancellor) on Sep 24, 2002 at 20:18 UTC

    Check $! to see if any error occured. See perldoc perlvar.

    Also, this isn't shell so you shouldn't be putting the variable name in quotes if you're only using it by itself. -s $filename is fine. If the variable you were trying to pass to -s were a filehandle glob reference, the quotes would actually break your code entirely by turning the reference into a useless string representation of its address.

    my $size = -s $filename;
die "Couldn't stat $filename: $!" if not defined $size;

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    Makeshifts last the longest.

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Re: Getting file size
by broquaint (Abbot) on Sep 24, 2002 at 20:19 UTC
    Have you checked to see if an error has occurred e.g 
    defined(my $size = -s $filename) or die "ack: $!";
# or using stat()
defined(my $size = [stat $filename]->[7]) or die "ack: $!";

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    As this is the most likely cause of your missing filesize.
    HTH

    _________
    broquaint

    update: changed code to check definedness instead of the truthfulness of size ... hmm I'm sure there's a joke in their somewhere

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Re: Getting file size
by thelenm (Vicar) on Sep 24, 2002 at 20:17 UTC
    Either one of those should be fine. Try looking at $filename itself to make sure it contains what you think it does. Also, there's no need for the double quotes around $filename when you use it by itself. You can just say $size = -s $filename.

    -- Mike

    --
    just,my${.02}

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Re: Getting file size
by vladb (Vicar) on Sep 24, 2002 at 20:17 UTC
    Google, Google, Google! Right here is an answer to your question ;-)

    Or, here's actually a closer match: Finding the FILE SIZE

    _____________________ 
    # Under Construction

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Re: Getting file size
by kabel (Chaplain) on Sep 24, 2002 at 20:25 UTC
    these are the two common ways (-s is more idiomatic).

    it seems that you do not use strict;. i suggest you to put it together with use warnings; at the top of your script.

    if $size is blank, an error has occured. you can check this by using this for example: 
    my $filename = "test.pl";
my $size = -s $filename;
unless ($size) {
    die "error getting file size [$filename]: [$!]";
}

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    then check the error and correct it.

    a common error seems to be the permission issue because the cgi script is executed using another user OR you are ín the wrong path (if relative). HTH
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      That will croak for 0-byte files though. You have to test for definedness, not falseness.

      Makeshifts last the longest.

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        yo, that's right. thanks for correction. <badjoke> exactly speaking, it will not croak, it will die :p </badjoke>
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      Thanks, I'm kinda new to this environment and the way they have it setup here in the office I don't have access to server logs (They use a NT box that kicks of a batch file to run the perl script, goes by so fast I can barely see the error messages.) This is a Perl script not a CGI file I dunno what difference that makes in this case.

      But I tryed your code with a file that is in the same directory as the script I am running and it dies for some strange reason.

      my $filename = "tools2.pl";
      my $size = -s $filename;
      unless ($size) { die "+++++***** error getting file size [$filename]: [$!] *****+++++";}

      I appreciate all the help I get from this site, everybody replied so darn fast!

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        aha. and what is the error message you are getting?
        and be sure to change the last line to 
        unless (defined $size) {...}

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        , as aristotle correctly suggested.
        it is always a good idea to log important issue to a file which either is specified in the script itself or can be specified via command line. any fatal error is an important issue.
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Re: Getting file size
by MZSanford (Curate) on Sep 24, 2002 at 21:30 UTC
    <sarcasim> 
    open(F,$filename) || die "Could not open file '$filename' : $!\n";
while (<F>) {
    $size += length($_);
}
close(F);

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    </sarcasim>
    from the frivolous to the serious
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      open(F, "> $filename") or die "Could not open file '$filename': $!\n";
close(F);
$size = 0;

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      I'll see your sarcasm and raise you one dose of pedantry :-)

      On Win32, your code would not work reliably unless you add binmode(F) since every CRLF pair will get converted to the single character LF.

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