Question

Able to Read but not Write to a file using PHP/Apache on CentOS

Posted December 27, 2019 536 views
CentOSApachePHP

$myfile = fopen(“testData.txt”, “r”) or die(“Unable to open file!”);
echo fread($myfile,filesize(“testData.txt”));
fclose($myfile);

Above works! The following fails using either “a”-append or “w”-write!

$myfile = fopen(“testData.txt”, “a”) or die(“Unable to open file!”);
$txt = “John Doe\n”;
fwrite($myfile, $txt);
$txt = “Jane Doe\n”;
fwrite($myfile, $txt);
fclose($myfile);

ls -l returns:
-rw-rw-rw-. 1 user user 24 Dec24 07:54 testData.txt

I am sure that it is a permissions issue somewhere, but no clue where to look. PHP file and the data file are in the same directory (I know this is not good practice - just trying to eliminate as many variables as possible).

Thank you in advance.

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revans2695
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2 answers
KDSys December 27, 2019

Hi @revans2695,

It’s possible you’ve or any other system has made the file immutable. Please execute the following command on the file

lsattr testData.txt

It will show you the attributes of the file. Example 

 lsattr test
----i---------e--- test

The above example shows the file has a tag of -i and -e. The -i tag means immutable while the -e tag means executable. To remove the -i tag, you would need to do

chattr -i test

Regards,
KDSys

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  • revans2695 December 27, 2019

    Thank you KDSys for the quick response.

    However, the lsattr command returns all ———————.

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    • KDSys December 27, 2019

      Hi @revans2695,

      I see, in that case try with a more permissive permissions to see if it would actually resolve the issue.

      If making the file executable like so 

      chmod +x nameOfFile

      works afterwards than it’s 100% permissions issue. If not we’ll continue from there

      Regards,
      KDSys

      Reply Report
      • revans2695 December 30, 2019

        Thank you for staying with me on this. I executed the command recommended above.

        The command: ls /var/www/html/xxxxxxxx/cronTestData.txt results
        -rwxrwxrwx. 1 userx userx 24 Dec 24 07:54

        I still get “Unable to open file!”

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        • KDSys December 30, 2019

          Hi @revans2695,

          This is getting really tricky. If you try and edit the file from the terminal you are not presented with any errors, correct?

          Reply Report
          • revans2695 December 31, 2019

            That is correct. I used the vi editor to edit the file and append a new line at the end of the file.

            The failure is occurring when I run the PHP file from a browser. Could it be a permissions issue somewhere because Apache is in a different group than the group the owner of the file is in.... even though the permissions on the file are set to -rwxrwxrwx. Here is the script:

            <?php

            echo (“Read ”);
            $myfile = fopen(“cronTestData.txt”, “r”) or die(“Read - Unable to open file!\n”);
            echo fread($myfile,filesize(“cronTestData.txt”));
            fclose($myfile);

            echo (“Write\n”);

            $myfile = fopen(“cronTestData.txt”, “a”) or die(“Write - Unable to open file!”);
            $txt = “John Doe\n”;
            fwrite($myfile, $txt);
            $txt = “Jane Doe\n”;
            fwrite($myfile, $txt);
            fclose($myfile);
            echo (“Write Success!\n”);

            ?>

            The read works fine and lists the four lines in the file. The write fails with: Write Write - Unable to open file!

            Thanks for your help on this. It is quite frustrating.

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KDSys January 1, 2020

Hi @revans2695,

It does seem exactly like that, if you are able to open it with the user from the shell and not from the browser, I would say exactly that.

Regards,
KDSys

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