Check for PHP Syntax errors?

Question

Well, I have run into a bit of a pickle here. I am needing to check some PHP for syntax errors. I noticed this bit that needs to run from the commandline:

php -l somefile.php

However, is there a way to run this from within a PHP file itself? I've been looking and have think that I can use parse_str function somehow to accomplish this by entering it into a $_GET, but can't quite understand how this works.

Someone else told me to use token_get_all() php function to determine this.

But I can't figure out how to do this with any approach? Can anyone here give me some sample code to get started perhaps?? I don't think using eval() is the way to go, although I had an eval($code) working, but don't think I should run the script if there are PHP syntax errors.

Any help on this is greatly appreciated, as always!

@SolomonClosson, I think he's terse comment is referring to http://php.net/manual/en/function.exec.php — Pacerier, Jan 28 '15 at 07:59

score 6 · Answer 1 · answered Aug 14 '12 at 21:10

6

You could simply do shell_exec() like this:

$output = shell_exec('php -l /path/to/filename.php');

This gives you the output of the command line operation in the string $output.

answered Aug 14 '12 at 21:10

Mike Brant

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Ok, have fixed the undefined output error, however, now it returns an empty string regardless if there are PHP Syntax errors or not. – Solomon Closson Aug 14 '12 at 22:13
1

Using exec() instead of shell_exec() will give you the output in the third parameter: http://www.php.net/manual/en/function.exec.php – Wolfgang Blessen May 05 '18 at 07:37

score 4 · Answer 2 · answered May 29 '17 at 07:25

4

It is safer to check the return status of php -l

$fileName = '/path/to/file.php';
exec("php -l {$fileName}", $output, $return);

if ($return === 0) {
    // Correct syntax
} else {
    // Syntax errors
}

See this fiddle to see it in action

answered May 29 '17 at 07:25

Mandy Schoep

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score 4 · Answer 3 · answered Aug 07 '18 at 19:16

I use token_get_all for this. I have some PHP code in the db. Before saving, I do

function is_valid_php_code_or_throw( $code ) {
        $old = ini_set('display_errors', 1);
        try {
                token_get_all("<?php\n$code", TOKEN_PARSE);
        }
        catch ( Throwable $ex ) {
                $error = $ex->getMessage();
                $line = $ex->getLine() - 1;
                throw new InvalidInputException("PARSE ERROR on line $line:\n\n$error");
        }
        finally {
                ini_set('display_errors', $old);
        }
}

Works like a charm. Syntax only. No missing variables, type incompayibility etc.

InvalidInputException is my own. You can make it anything, or return a bool, or handle the exception yourself.

I'm not sure if display_errors is necessary. It was at some point.

Eh. That's weird. But you should add the `TOKEN_PARSE` flag: https://3v4l.org/VFDrG — Rudie, May 19 '20 at 18:11

score 0 · Answer 4 · answered Dec 14 '15 at 10:12

0

I would do it like this:

$php_file = 'The path to your file';
if(substr(`php -l $php_file`, 0, 16) == 'No syntax errors') {
    // Correct syntax
} else {
    // Error
}

answered Dec 14 '15 at 10:12

Samuil Banti

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wanovak · Answer 5 · 2012-08-14T21:08:15.283

-1

php_check_syntax should do the trick. If you're running PHP >= 5.05, see the first comment in the comments section for the implementation.

edited Aug 14 '12 at 21:08

answered Aug 14 '12 at 21:03

wanovak

6,117
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7

This function was removed from PHP... [link](http://www.php.net/manual/en/function.php-check-syntax.php) – Solomon Closson Aug 14 '12 at 21:06
Good catch @SolomonClosson. OP, luckily in the comments is an implementation that you can use. I won't paste it here as it's very large, but it's the top comment. – wanovak Aug 14 '12 at 21:07
2

This is a PHP4 function and has been removed in PHP 5.0.x. Moreover it was basically just an alias to `eval()` - it just ran the supplied code to detect parsing errors. – mario Aug 14 '12 at 21:08

score -1 · Answer 6 · edited May 23 '17 at 11:53

You can use exec to check for syntax errors.

$tempFile = path/of/file
$syntaxParseError = strpos(exec('php -l '.$tempFile), 'No syntax errors detected') === false;`

Unfortunately, this will not give you the line number or tell you anything about the error. For that you will either need to install static analyzer on your server Is there a static code analyzer [like Lint] for PHP files? or write your own parser.

NB. token_get_all() will not determine anything on its own, but it useful function for making a parser.

kjdion84 · Answer 7 · 2017-07-17T06:41:39.037

-1

Why use the shell at all?

function syntax_is_valid($code)
{
    try
    {
        @eval($code);
    }
    catch (ParseError $e)
    {
        return false;
    }

    return true;    
}

Alternatively use $e->getMessage() for more info.

edited Jul 17 '17 at 06:41

answered Jul 17 '17 at 05:14

kjdion84

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5

How do you prevent all the side effects from running (evaling) the code? Such as printing, connecting to the database, writing files, etc. – CJ Dennis Oct 08 '17 at 22:56

Check for PHP Syntax errors?

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