How do I search for string and insert new line

See more:

PHP

my txt file looks like this

text
sub text 1
sub text 2
sub text 3
text2
sub text2 1
sub text2 2
sub text2 3
text3
sub text3 1
sub text3 2
sub text3 3
so i want to search for text2 and then insert text with tab right below it or on the last line just befor text3


Below is the code i got to search for the string


outcome wanted

add new text

text
sub text 1
sub text 2
sub text 3
text2
sub text2 1
sub text2 2
sub text2 3
new text
text3
sub text3 1
sub text3 2
sub text3 3

What I have tried:

<pre lang="PHP"><?php
$input = "text2;
function find_value($input) {
$handle = @fopen("/users/edwin/list.txt", "r");
if ($handle) {
  while (!feof($handle)) {
    $entry_array = explode(":",fgets($handle));
    if ($entry_array[0] == $input) {
      return $entry_array[1];
      }
    }
  fclose($handle);
  }
return NULL;
}
?>