[RESOLVED] Looking for a file update example.

mikie46

Im looking for a good example (code) of a file update procedure using flat files.

For eg, i would like to read the contents of the file then update it based on user changes.

Example, read a file contents into an array, allows changes, rewrite or update the contents of the file.

Im sorry, but this very simple example seems to be lacking on the entire net. Anyone have any good examples that work? From what iv seen php cannot do update via key. Everything must be processed sequentially, this would mean one needs to read in the entire file then rewrite the new contents.

Thank you.

troybtj

This one uses a system call on grep to find the files, but the file open/edit/save is in PHP:

(From Zend Studio Code Snippets)


A global search and replace using PHP.
You'll need to specify several parameters as GET/POST parameters:
oldword=[text to replace]
newword=[new text]
rootpath=[path to dir containing files to alter]

Note also that PHP must have read/write access to the files to alter them.



Code:

<?php
	exec("/bin/grep -r '$oldword' $rootpath", $results, $errorCode);
	if ($errorCode){
		if ($errorCode == 1){
			echo "Possibly no files were found with $oldword in them<BR>\n";
		}
	  echo "OS Error: $errorCode<BR>\n";
	  echo "Check 'man errno' and count down<BR>\n";
	  echo "Usually paths/permissions<BR>\n";
	}
	while (list(,$path) = each($results)){
		$parts = explode(':', $path);
		$path = $parts[0];
	  $fp = fopen($path, 'r') or print("Cannot read $path<BR>\n");

  if ($fp){
    $data = fread($fp, filesize($path));
    fclose($fp);
    $newdata = str_replace($oldword, $newword, $data);
    $fp = fopen($path, 'w') or print("Cannot write $path<BR>\n");
    if ($fp){
      fwrite($fp, $newdata);
      fclose($fp);
      echo $path, "<BR>\n";
    }
  }
}
?>

Weedpacket

mikie46 wrote:
From what iv seen php cannot do update via key. Everything must be processed sequentially, this would mean one needs to read in the entire file then rewrite the new contents.

Two things about this.

First, you can have two files, writing to one while you're reading to another.
If you want to look things up by key, then you need an index in which you look up the key, and you don't have a flat file system any more. Once you do have an index file of course, you can store file offsets in it, and then use [man]fseek[/man] to go directly to that point in the file to alter it. Of course, that means that all of your records need to be fixed in size, because if one changes size then all of the records that follow will have to be shifted - effectively requiring the entire file to be read in and written out again - and don't forget to update the index file to bring those offsets back into sync.

Unless you're setting out to reinvent the wheel for some reason, you might want to consider using [man]SQLite[/man].

mikie46

I just need an example of how to update a file. Iv looked everywhere.

What i would like to do is this.

A file has the following inside it.

test1=value
text2=value
text3=value
test4=value

I simply want to be able to update any value in the file.

halojoy

then you have
a good function for this
PHP Manual: [man]parse_ini_file[/man]

I would also search our forum for: parse_ini_file
... I am sure there are good eamples of code in older topics

How you would do this practical,
depends a bit on how secure you want those values to be.
php-files can have a first line to stop direct access

🙂

NogDog

<?php
function updateFile($file, $key, $value)
{
   if(!file_exists($file) or !is_writable($file))
   {
      user_error("$file does not exist or is not writable.");
      return(FALSE); // might want to throw exception or raise error here
   }
   $linesChanged = 0;
   $data = file($file);
   foreach($data as $ix => $line)
   {
      $parts = preg_split('/\s*=\s*/', $line, 2);
      if(count($parts) == 2 and $parts[0] == $key)
      {
         $data[$ix] = "$key=$value\n";
         $linesChanged++;
      }
      $fh = fopen($file, 'w');
      fwrite($fh, implode('', $data));
      fclose($fh);
   }
   return($linesChanged);
}
// sample usage
$linesUpdated = updateFile('test.ini', 'test1', 'This is a test');

mikie46

THanks NogDog ill give that a test.

mikie46

NogDog wrote:

<?php
function updateFile($file, $key, $value)
{
   if(!file_exists($file) or !is_writable($file))
   {
      user_error("$file does not exist or is not writable.");
      return(FALSE); // might want to throw exception or raise error here
   }
   $linesChanged = 0;
   $data = file($file);
   foreach($data as $ix => $line)
   {
      $parts = preg_split('/\s*=\s*/', $line, 2);
      if(count($parts) == 2 and $parts[0] == $key)
      {
         $data[$ix] = "$key=$value\n";
         $linesChanged++;
      }
      $fh = fopen($file, 'w');
      fwrite($fh, implode('', $data));
      fclose($fh);
   }
   return($linesChanged);
}
// sample usage
$linesUpdated = updateFile('test.ini', 'test1', 'This is a test');

This works great!! Thanks a million. Should i be worried about any file locking situation? Also, how do i mark a thread resolved.

troybtj

Click on "Thread Tools" at the top (Drop Down Menu), and mark as resolved.