How do I read a file's contents into a Perl scalar? - html

Question

what i am trying to do is get the contents of a file from another server. Since im not in tune with perl, nor know its mods and functions iv'e gone about it this way:
my $fileContents;
if( $md5Con =~ m/\.php$/g ) {
my $ftp = Net::FTP->new($DB_ftpserver, Debug => 0) or die "Cannot connect to some.host.name: $#";
$ftp->login($DB_ftpuser, $DB_ftppass) or die "Cannot login ", $ftp->message;
$ftp->get("/" . $root . $webpage, "c:/perlscripts/" . md5_hex($md5Con) . "-code.php") or die $ftp->message;
open FILE, ">>c:/perlscripts/" . md5_hex($md5Con) . "-code.php" or die $!;
$fileContents = <FILE>;
close(FILE);
unlink("c:/perlscripts/" . md5_hex($md5Con) . "-code.php");
$ftp->quit;
}
What i thought id do is get the file from the server, put on my local machine, edit the content, upload to where ever an then delete the temp file.
But I cannot seem to figure out how to get the contents of the file;
open FILE, ">>c:/perlscripts/" . md5_hex($md5Con) . "-code.php" or die $!;
$fileContents = <FILE>;
close(FILE);
keep getting error;
Use of uninitialized value $fileContents
Which im guessing means it isn't returning a value.
Any help much appreciated.
>>>>>>>>>> EDIT <<<<<<<<<<
my $fileContents;
if( $md5Con =~ m/\.php$/g ) {
my $ftp = Net::FTP->new($DB_ftpserver, Debug => 0) or die "Cannot connect to some.host.name: $#";
$ftp->login($DB_ftpuser, $DB_ftppass) or die "Cannot login ", $ftp->message;
$ftp->get("/" . $root . $webpage, "c:/perlscripts/" . md5_hex($md5Con) . "-code.php") or die $ftp->message;
my $file = "c:/perlscripts/" . md5_hex($md5Con) . "-code.php";
{
local( $/ ); # undefine the record seperator
open FILE, "<", $file or die "Cannot open:$!\n";
my $fileContents = <FILE>;
#print $fileContents;
my $bodyContents;
my $headContents;
if( $fileContents =~ m/<\s*body[^>]*>.*$/gi ) {
print $0 . $1 . "\n";
$bodyContents = $dbh->quote($1);
}
if( $fileContents =~ m/^.*<\/head>/gi ) {
print $0 . $1 . "\n";
$headContents = $dbh->quote($1);
}
$bodyTable = $dbh->quote($bodyTable);
$headerTable = $dbh->quote($headerTable);
$dbh->do($createBodyTable) or die " error: Couldn't create body table: " . DBI->errstr;
$dbh->do($createHeadTable) or die " error: Couldn't create header table: " . DBI->errstr;
$dbh->do("INSERT INTO $headerTable ( headData, headDataOutput ) VALUES ( $headContents, $headContents )") or die " error: Couldn't connect to database: " . DBI->errstr;
$dbh->do("INSERT INTO $bodyTable ( bodyData, bodyDataOutput ) VALUES ( $bodyContents, $bodyContents )") or die " error: Couldn't connect to database: " . DBI->errstr;
$dbh->do("INSERT INTO page_names (linkFromRoot, linkTrue, page_name, table_name, navigation, location) VALUES ( $linkFromRoot, $linkTrue, $page_name, $table_name, $navigation, $location )") or die " error: Couldn't connect to database: " . DBI->errstr;
unlink("c:/perlscripts/" . md5_hex($md5Con) . "-code.php");
}
$ftp->quit;
}
the above using print WILL print the whole file. BUT, for some reason the two regular expresions are returning false. Any idea why?
if( $fileContents =~ m/<\s*body[^>]*>.*$/gi ) {
print $0 . $1 . "\n";
$bodyContents = $dbh->quote($1);
}
if( $fileContents =~ m/^.*<\/head>/gi ) {
print $0 . $1 . "\n";
$headContents = $dbh->quote($1);
}

Answer 1

This is covered in section 5 of the Perl FAQ included with the standard distribution.
How can I read in an entire file all at once?
You can use the Path::Class::File::slurp module to do it in one step.
use Path::Class;
$all_of_it = file($filename)->slurp; # entire file in scalar
#all_lines = file($filename)->slurp; # one line per element
The customary Perl approach for processing all the lines in a file is to do so one line at a time:
open (INPUT, $file) || die "can't open $file: $!";
while (<INPUT>) {
chomp;
# do something with $_
}
close(INPUT) || die "can't close $file: $!";
This is tremendously more efficient than reading the entire file into memory as an array of lines and then processing it one element at a time, which is often—if not almost always—the wrong approach. Whenever you see someone do this:
#lines = <INPUT>;
you should think long and hard about why you need everything loaded at once. It's just not a scalable solution. You might also find it more fun to use the standard Tie::File module, or the DB_File module's $DB_RECNO bindings, which allow you to tie an array to a file so that accessing an element the array actually accesses the corresponding line in the file.
You can read the entire filehandle contents into a scalar.
{
local(*INPUT, $/);
open (INPUT, $file) || die "can't open $file: $!";
$var = <INPUT>;
}
That temporarily undefs your record separator, and will automatically close the file at block exit. If the file is already open, just use this:
$var = do { local $/; <INPUT> };
For ordinary files you can also use the read function.
read( INPUT, $var, -s INPUT );
The third argument tests the byte size of the data on the INPUT filehandle and reads that many bytes into the buffer $var.

Answer 2

Use Path::Class::File::slurp if you want to read all file contents in one go.
However, more importantly, use an HTML parser to parse HTML.

Answer 3

open FILE, "c:/perlscripts" . md5_hex($md5Con) . "-code.php" or die $!;
while (<FILE>) {
# each line is in $_
}
close(FILE);
will open the file and allow you to process it line-by-line (if that's what you want - otherwise investigate binmode). I think the problem is in your prepending the filename to open with >>. See this tutorial for more info.
I note you're also using regular expressions to parse HTML. Generally I would recommend using a parser to do this (e.g. see HTML::Parser). Regular expressions aren't suited to HTML due to HTML's lack of regularity, and won't work reliably in general cases.

Answer 4

Also, if you are in need of editing the contents of the files take a look at the CPAN module
Tie::File
This module relieves you from the need to creation of a temp file for editing the content
and writing it back to the same file.
EDIT:
What you are looking at is a way to slurp the file. May be you have to undefine
the record separator variable $/
The below code works fine for me:
use strict;
my $file = "test.txt";
{
local( $/ ); # undefine the record seperator
open FILE, "<", $file or die "Cannot open:$!\n";
my $lines =<FILE>;
print $lines;
}
Also see the section "Traditional Slurping" in this article.

Answer 5

BUT, for some reason the two regular expresions are returning false. Any idea why?
. in a regular expression by default matches any character except newline. Presumably you have newlines before the </head> tag and after the <body> tag. To make . match any character including newlines, use the //s flag.
I'm not sure what your print $0 . $1 ... code is about; you aren't capturing anything in your matches to be stored in $1, and $0 isn't a variable used for regular expression captures, it's something very different.

Answer 6

if you want to get the content of the file,
#lines = <FILE>;

Answer 7

Use File::Slurp::Tiny. As convenient as File::Slurp, but without the bugs.