Delete a specific line in a TXT file - php

Question

I have a .txt file with millions of lines of text
The code below Delete a specific line (.com domains) in a .txt file. But large files can not do :(
<?php
$fname = "test.txt";
$lines = file($fname);
foreach($lines as $line) if(!strstr($line, ".com")) $out .= $line;
$f = fopen($fname, "w");
fwrite($f, $out);
fclose($f);
?>
I want to remove certain lines and put them in another file
For example, the list of domain names of sites. cut the .com domain and paste it in another file...

Answer 1

Here's an approach using http://php.net/manual/en/class.splfileobject.php and working with a temporary file.
$fileName = 'whatever.txt';
$linesToDelete = array( 3, 5 );
// Working File
$file = new SplFileObject( $fileName, 'a+' );
$file->flock( LOCK_EX );
// Temp File
$temp = new SplTempFileObject( 0 );
$temp->flock( LOCK_EX );
// Wite the temp file without the lines
foreach( $file as $key => $line )
{
if( in_array( $key + 1, $linesToDelete ) === false )
{
$temp->fwrite( $line );
}
}
// Write Back to the main file
$file->ftruncate(0);
foreach( $temp as $line )
{
$file->fwrite( $line );
}
$file->flock( LOCK_UN );
$temp->flock( LOCK_UN );
This may be slow though, but a 40 meg file with 140000 lines takes 2.3 seconds on my windows xampp setup. This could be sped up by writing to a temp file and doing a file move, but I didn't want to step on file permissions in your environment.
Edit: Solution using Rename/Move instead of second write
$fileName = __DIR__ . DIRECTORY_SEPARATOR . 'whatever.txt';
$linesToDelete = array( 3, 5 );
// Working File
$file = new SplFileObject( $fileName, 'a+' );
$file->flock( LOCK_EX );
// Temp File
$tempFileName = tempnam( sys_get_temp_dir(), rand() );
$temp = new SplFileObject( $tempFileName,'w+');
$temp->flock( LOCK_EX );
// Write the temp file without the lines
foreach( $file as $key => $line )
{
if( in_array( $key + 1, $linesToDelete ) === false )
{
$temp->fwrite( $line );
}
}
// File Rename
$file->flock( LOCK_UN );
$temp->flock( LOCK_UN );
unset( $file, $temp ); // Kill the SPL objects relasing further locks
unlink( $fileName );
rename( $tempFileName, $fileName );

Answer 2

It could be because of the large size of the file that its taking too much of space.
When you do file('test.txt'), it reads the entire file into an array.
Instead, you can try using Generators.
GeneratorsExample.php
<?php
class GeneratorsExample {
function file_lines($filename) {
$file = fopen($filename, 'r');
while (($line = fgets($file)) !== false) {
yield $line;
}
fclose($file);
}
function copyFile($srcFile, $destFile) {
foreach ($this->file_lines($srcFile) as $line) {
if(!strstr($line, ".com")) {
$f = fopen($destFile, "a");
fwrite($f, $line);
fclose($f);
}
}
}
}
callingFile.php
<?php
include('GeneratorsExample.php');
$ob = new GeneratorsExample();
$ob->copyFile('file1.txt', 'file2.txt')

Answer 3

While you could use tens of lines of PHP code, one line of shell code will do.
$ grep Bar.com stuff.txt > stuff2.txt
or as PHP
system ("grep Bar.com stuff.txt > stuff2.txt");