Copying Contents of File

killswytch

Hello,

I have been wracking my brain trying to figure out how to write the contents of one file to another, without overwriting what is in the other. I have a user interface, where the end user puts in their informatin, and it enters it into this file. Now I want the new information to go at the top of the file. So what I have done is in my code, I open up the originalfile and copying it with an extension of .bak

After that is succesfull, I open up the original with "w" permission, write the new lines in and then close the file. Then I am trying to copy the contents of the .bak file into the new file with the new lines..only appending to the new file so we don't delete the new lines. Here is a sample of my code.

If ($submit)
{

$copy = "users";
If (!copy($copy , $copy.".bak"))
{
	echo "could not copy file";
	exit();
}
else
{

	If (!$file=fopen("users", "w"))
	{
		echo "could not open file";
	}
	else
	{

		$text = "#\n";
		$text .= "$user			password = \"$password\"\n";
		$text .= "			Service-Type = Framed User,\n";
		$text .= "			Idle-Timout = 1800,\n";
		$text .= "			Framed-Routing = None,\n";
		$text .= "			Framed-Filter-Id = \"std.ppp\"\n";
		$text .= "#\n";

		If(!$fput = fputs($file, $text))
		{
			echo "could not write to file";
			exit();
		}
		else
		{
			echo "writing to file successful!";
			fclose($file);
		}
	}

}

If (!$file=fopen("users.bak", "r"))
{
	echo "could not open file";
	exit();
}
else
{

	If (!$user = fopen("users", "a+"))
	{
		echo "could not reopen users file";
		exit();
	}


	If(!$again = fputs($user, $file))
	{
		echo "could not rewrite file to users";
		exit();
	}
	else
	{
		echo "copying of file successful";
	}
}

}

Any help would be great..

Thanks

pnoeric

Depending on how big the file will be, it might be easier just to read the entire file into a string, append the information to the top of the string, and write the whole string back out.

killswytch

Thanks for the input...but a.) I am not quite sure how to go about putting the entire file into a string? b.) the file size is rather large, but I would be interested if you could explain the above!

pnoeric

Hi Jason,

to put a file into a string, you could fopen/fread the file, getting a chunk at a time and appending it, or use the file(); function. (see php.net/file)
I don't know how big the data file will end up-- rather large could mean 6k, 60k, 600k or 6 megs :-) I suspect you'd see a performance hit before you'd hit the edges of what a string can hold in PHP (which I don't know off the top of my head)... try writing that code and see how it works for you... it's something like:

$newinfo = "this goes at the top of the file";
$fname = "my_data_file.txt";
$data = file($fname);
//put the new data at the start of the file
$data .= $newinfo;

then fopen, fwrite, fclose the data back out into $fname... this is off the top of my head so there is probably a more optimized/elegant way to do this, but you get the gist.

best,
Eric

killswytch

Hi Eric,

Thanks so much for your help. Eveything worked fine except for one small thing. Before it writes the new information, it's writing the word Array. I'm sure that has to do with putting the contents of the text file into the file() function. Any suggestions to make it stop doing this?

Thanks

kparker

As an alternative, consider writing the data to a temporary file first, in which case you can just write the new data first followed by the existing data. Then, if all goes well, (a) delete the .bak file, rename the original file to the .bak file, and rename the tmp file to the original name. (Note this does not preserve the file permissions on the original file, so beware if the permissions must be other than the default!)

In code (in real life you'd probably want to do something more graceful than die at the first sign of error!):

   
   function insert_new_data( $new_data, $filename )
   {
   $tmp_filename = $filename . getmypid();
$   bak_filename = $filename . ".bak";

   $tmpf = fopen($tmp_filename,"w") or die("Can't make tmp");
   fwrite( $tmpf, $new_data );
   $oldf = fopen( $filename, "r");
   while (!feof($oldf))
      {
      $data = fgets($oldf, 65536);
      fwrite( $tmpf, $data );
      }
   fclose ($oldf);
   fclose ($tmpf);
   unlink( $bak_filename );
   rename( $filename, $bak_filename );
   rename( $tmp_filename, $filename );
   }

And what posting of mine would be complete without a warning that it's not multi-user safe? :-) If you do need to guard against this, you should have a separate file you use to lock, as the flock() call will not survive the file being
closed.

pnoeric

Jason - check out Kirk's message below, he proposes a simple solution that also avoids the potential filesize/variable size problem.

To answer your question - PHP prints the word "Array" if you try to echo an array value. You need echo each item in the array with a simple loop to walk the array; lots of examples at php.net/foreach or php.net/array.

best,
Eric