如何突出显示要下载的文件中的字符串？

Question

I have a text file "output.txt" which is an output of a shell command. I want to highlight certain words taken as $_GET['word'] in that file and then allow to download using href.

I have seen multiple questions but none of them seems to be working in this case.

1. Highlight multiple keywords from a given string
2. highlight the word in the string, if it contains the keyword

Code:

$cmd = shell_exec("/usr/local/bin/clustalw2 -infile=input.txt -tree -type=protein -case=upper &");
$file = 'output.txt';
$content = explode("
",file_get_contents("output.txt"));
$keyword = $_GET['word'];
$content = str_replace($keyword,'<span style="color:red">'.$keyword.'</span>',$content);
$file = file_put_contents($file, $content);
echo "<a href='http://some.thing.com/folder/output.txt'>Download Result file</a>";

It is not giving any error neither highlighting the text.

Answer 1

I suspect the trouble is with opening the initial file. The following did work for me.

I created /home/input.txt:

this is a test
that may
or may not work.

Then ran:

$cmd = shell_exec(" cp /home/input.txt output.txt");
$file = 'output.txt';
$content = explode("
",file_get_contents("output.txt"));
$keyword = "may";
$content = str_replace($keyword,'<span style="color:red">'.$keyword.'</span>',$content);
$file = file_put_contents($file, implode("
", $content));
echo "<a href='http://some.thing.com/folder/output.txt'>Download Result file</a>";

And the output.txt is now:

this is a test
that <span style="color:red">may</span>
or <span style="color:red">may</span> not work.