How can I replace a particular line of text in file using php?
I don't know the line number. I want to replace a line containing a particular word.
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');
}