Yes, it creates the full text file before writing it. You could write each time but at 5000+ times that could cause some issues. Unless absolutely necessary, I wouldn't do it that way. Here is the code anyways..
PHP Code:
<?php
$search = "google"; // Your seach string
if ( ( $websites = file( "websites.txt" ) ) !== false )
{
foreach( $websites as $url )
{
$url = trim( $url );
$contents = file_get_contents( $url );
if ( ( strpos( $contents, $search ) ) !== false )
{
if ( ( $handle = fopen( "valid.txt", 'at' ) ) !== false )
{
fwrite( $handle, "{$url}\n" );
fclose( $handle );
}
}
else
{
if ( ( $handle = fopen( "bad.txt", 'at' ) ) !== false )
{
fwrite( $handle, "{$url}\n" );
fclose( $handle );
}
}
sleep( 10 ); // 10 second timeout between URLs
}
}
?>