PHP exec command works in shell and php command line but not on website

Question

I have a problem where I am trying to copy a file that is generated on a server drive that I have mounted using the php exec command. However, the command doesn't work (although the return status is 1) when called from a web-page.

$src = "/mnt/...";
$dest = "/var/www/...";
exec("cp $src $dest");

I have tried printing out the command to make sure it is correct, and it is. I have also tried making sure the file exists before attempting to copy it and it is.

if (file_exists($src)) {
    exec("cp $src $dest");
}

Copying the command directly into the terminal works.

$ >cp /mnt/... /var/www/...

I've also tried using the php command line tool to run the exec command and that also works.

$ >php -r 'exec("cp /mnt/... /var/www/...");'

I have also tried using shell_exec as well, with the same results.

This is probably because php is being run under a different user on the system, and that that user does not have the rights to do that action on those files. You could look into sudo to perform this — Frank
– Frank, Commented Aug 27, 2013 at 18:15
Last time I had this error, I didn't think of looking at the status code so I can't be sure of that, sorry. But using sudo did fix my problems — Frank
– Frank, Commented Aug 27, 2013 at 18:32
I bet PHP doesn't have permissions to either copy the file from source, or it doesn't have permissions to copy to the destination. Or it could be both. — Get Off My Lawn
– Get Off My Lawn, Commented Aug 27, 2013 at 18:33
Try to check is_writable($dest). Chances are it's false, which means, as others have said, the PHP user cannot write to it. Usually PHP is ran as the apache (www-data) or nobody user. Run echo exec("whoami"); to see the user it's running as. — gen_Eric
– gen_Eric, Commented Aug 27, 2013 at 18:44

Shahin ILDEREMI · Accepted Answer · 2020-10-07 20:13:04Z

1

Hostings usually disable the shell commands. On your local, you can edit your php.ini and add this line to disable the functions you want:

disable_functions =exec,passthru,shell_exec,system,proc_open,popen,curl_exec,curl_multi_exec,parse_ini_file,show_source

But on your live website, you need to contact your host provider to enable the functions that are disabled by default.

answered Oct 7, 2020 at 20:13

Shahin ILDEREMI

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Get Off My Lawn · Accepted Answer · 2013-08-27 18:46:53Z

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You can add the second parameter to help debug, $output will display what the cp command is doing, whether it be an error or not.

I would also recommend placing quotes around the files, just in case something with a space gets in there.

$src = "/mnt/...";
$dest = "/var/www/...";
exec("cp '$src' '$dest'", $output, $retrun_var);

var_dump($output, $retrun_var);

edited Aug 27, 2013 at 18:46

answered Aug 27, 2013 at 18:37

Get Off My Lawn

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Community · Accepted Answer · 2017-05-23 11:58:35Z

0

I had a similar issue a while ago. It was essentially what all the commentators are saying. The user/permission of the web server are restricted, but also the shell environment that is being used and/or the PATH environment variable.

edited May 23, 2017 at 11:58

CommunityBot

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answered Aug 27, 2013 at 19:09

Wayne Weibel

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