Overwrite Line in File with PHP

Replace a whole line where a particular word is found in a text file

One approach that you can use on smaller files that can fit into your memory twice:

$data = file('myfile'); // reads an array of lines
function replace_a_line($data) {
   if (stristr($data, 'certain word')) {
     return "replacement line!\n";
   }
   return $data;
}
$data = array_map('replace_a_line', $data);
file_put_contents('myfile', $data);

A quick note, PHP > 5.3.0 supports lambda functions so you can remove the named function declaration and shorten the map to:

$data = array_map(function($data) {
  return stristr($data,'certain word') ? "replacement line\n" : $data;
}, $data);

You could theoretically make this a single (harder to follow) php statement:

file_put_contents('myfile', implode('', 
  array_map(function($data) {
    return stristr($data,'certain word') ? "replacement line\n" : $data;
  }, file('myfile'))
));

Another (less memory intensive) approach that you should use for larger files:

$reading = fopen('myfile', 'r');
$writing = fopen('myfile.tmp', 'w');

$replaced = false;

while (!feof($reading)) {
  $line = fgets($reading);
  if (stristr($line,'certain word')) {
    $line = "replacement line!\n";
    $replaced = true;
  }
  fputs($writing, $line);
}
fclose($reading); fclose($writing);
// might as well not overwrite the file if we didn't replace anything
if ($replaced) 
{
  rename('myfile.tmp', 'myfile');
} else {
  unlink('myfile.tmp');
}

Php replace line in a file txt

You can either use the FILE_IGNORE_NEW_LINES constant in file() or don't use more newlines:

file_put_contents($myFile , implode('', $lines));

Or just this as it will be imploded for you:

file_put_contents($myFile , $lines);

But you'll need to add a newline here:

$lines[3] = $_POST['title'] . "\n";

So this might be the most straight forward:

$lines = file($myFile, FILE_IGNORE_NEW_LINES);
$lines[3] = $_POST['title'];
file_put_contents($myFile , implode("\n", $lines));

Replace specific line in text file using php while preserving to rest of the file

There are two solutions thanks to Cheery and Dagon.

Solution one

<?php
session_start();
// Get text file contents as array of lines
$filepath = '../path/file.txt';
$txt = file($filepath); 
//check post
if (isset($_POST["input"]) && 
    isset($_POST["hidden"])) {
    $line = $_POST['hidden'];
    $update = $_POST['input'] . "\n";
    // Make the change to line in array
    $txt[$line] = $update; 
    // Put the lines back together, and write back into txt file
    file_put_contents($filepath, implode("", $txt));
    //success code
    echo 'success';
} else {
    echo 'error';
}
?>

Solution two

<?php
session_start();
// Get text file contents as array of lines
$filepath = '../path/file.txt';
$txt = file($filepath); 
// Get file contents as string
$content = file_get_contents($filepath);
//check post
if (isset($_POST["input"]) && 
    isset($_POST["hidden"])) {
    $line = $_POST['hidden'];
    $update = $_POST['input'] . "\n";
    // Replace initial string (from $txt array) with $update in $content
    $newcontent = str_replace($txt[$line], $update, $content);
    file_put_contents($filepath, $newcontent);
    //success code
    echo 'success';
} else {
    echo 'error';
}
?>

Overwrite Line in File with PHP

If the file isn't too big, the best way would probably be to read the file into an array of lines with file(), search through the array of lines for your string and edit that line, then implode() the array back together and fwrite() it back to the file.

Replace line in text file using PHP

You don't need a regex for this. Try the following:

• Load the file into an array using file() and loop through the lines
• Check if the string starts with 2_
• If it does, replace it with the input $word and concatenate it to the $result string
• If if doesn't, simply concatenate it to the $result string
• Use file_get_contents() and write the result to the file

Code:

$lines = file('file.txt');
$word = 'word';
$result = '';

foreach($lines as $line) {
    if(substr($line, 0, 2) == '2_') {
        $result .= '2_'.$word."\n";
    } else {
        $result .= $line;
    }
}

file_put_contents('file.txt', $result);

Now, if the replace took place, then file.txt would contain the something like:

1_fjd
2_word
3_fks

how to replace one line of a file with php

As deceze♦ mentioned, unless the line is of fixed length, the easiest way is to process the whole file and output it to a new file.

Create a variable $newdata to append the processed data.

If your strpos statement !== false then you can change that text with the $replace_text variable and append that instead.

Once the loop has finished save your output to a new file. (If PHP has the appropriate permissions)

$file = fopen("file.dat", "a+");
    
      
$eqs = file_get_contents("file.dat");
$eqs = preg_split( "/\n/", $eqs );

$newdata = "";

foreach ($eqs as $valor) {
  if(strpos($valor, $sn) !== false){
        echo $valor; //this is the line to replace
        $replace_text = "test";
        $newdata = $newdata.$replace_text."/\n/";
    } else{
        $newdata = $newdata.$valor."/\n/";
    }
}

$myfile = fopen("newfile.dat", "w") or die("Unable to open file!");
fwrite($myfile, $newdata);
fclose($myfile);

PHP | Replace line in large txt-file

You should use PHP's file() function for that. It will return an array containing each line.

$file = file('path/to/text.txt');
$lines = array_map(function ($value) { return rtrim($value, PHP_EOL); }, $file);
$lines[3] = 'New content for line 4';
$lines = array_values($lines);

To save it again, implode the array with newline:

$content = implode(PHP_EOL, $lines);
file_put_contents('path/to/your/file.txt', $content);

PHP: Replace line in a file or add if not found

You can do something like this:

$message_exists = false;

$filename = 'messages.txt';
$data = file($filename);
file_put_contents($filename, implode('', 
  array_map(function($data) use (&$message_exists){
    $result = substr($data, 0, strlen('aabbcc|')) === 'aabbcc|';
    if($result)
    {
        $message_exists = true;
    }
    return $result ? "aabbcc|This would be a NEW line.\n" : $data;
  }, file($filename))
));

if(!$message_exists)
{
    file_put_contents($filename, "aabbcc|This would be a NEW line.\n", FILE_APPEND);
}

Replace text file line by line number

If you use the fact that file_put_contents() can take an array and just write it out, there is a simpler version which just takes the original contents of file() (including the new lines it will load automatically) and then replace the corresponding line (using array notation [$needle]) but add a new line onto the data (PHP_EOL to be generic). Then just write this array out.

$arr = file('file.txt'); // text to array

$content = "";
$needle = 3; // the line number you want to edit
$replace = 'PHP script'; // the replacement text

$arr[$needle] = $replace . PHP_EOL;
file_put_contents('file.txt', $arr);

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