php文件处理：
https://www.jb51.net/w3school/php/php_file.htm
<?php
$filename=dirname(__FILE__)."/readfrom.txt";
$ofilename=dirname(__FILE__)."/writeto.txt";
if(!file_exists($filename)){
echo $filename." not found!";
exit;
}
$fp=fopen($filename,"r");
$fo = fopen($ofilename,"w");
while(!feof($fp)){
$record=fgets($fp);
if($record!=NULL){
$record_arr=explode("\t", $record);
fwrite($fo,$record,strlen($col));
}
}
fclose($fo);
fclose($fp);
?>