Hi there I have a program that has been written to perform a SQL query (not a particularly slow or complicated one), write the results to a file and then extract information to be used in another program. This is the code so far. 
#!/usr/local/bin/perl -w

# General perl libraries

use strict;
use English;
use DBI;

# output file

my $outputfile = $ARGV[0];

open(FILE, ">>$outputfile")
    || die "Error: Can't open $outputfile for writing: $!\n";

my $dbh = DBI->connect("dbi:Pg:database;host=dbhost", 
"user", "userpwd", {AutoCommit => 1});

my $sth = $dbh->prepare("Tried and tested SQL query that simply return
+s a list of id numbers");

$sth->execute();

#print values

while(my $ref = $sth->fetchrow_hashref()) {
    print FILE "$ref->{'id'}\n";
}

$sth->finish();

# disconnect from database

$dbh->disconnect();

SendtoPrepare($outputfile);

###################################################################

sub SendtoPrepare
{
    my($file) = @_;

    print "$file\n";

    open(INFILE, "$file")
    || die "Error: Can't open $file for reading: $!\n";

    my @code = <INFILE>;

    print "@code\n";

}

[download]
Quite simple really but what i dont understand is that the code wont print out the @code array unless I run the script twice. The file the subroutine reads is created on the first run but I think its not created quickly enough to then be processed in the subroutine. Hence why the subroutine only prints out the array after the second run (because the file was obviously been completely written by then).
I guess this problem is due to wanting to do something with the file before its completely written but who might I halt the program slightly so that I ensure the file is written before going though to the subroutine?
Any help much appreciated

In reply to slowing down perl script to ensure file is written before program tries to process it in subroutine by Angharad

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