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problems with exec()

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  problems with exec() 7segment <7segment@nowhere.com> - 2012-04-15 11:37 -0500
    Re: problems with exec() 7segment <7segment@nowhere.com> - 2012-04-15 11:47 -0500
      Re: problems with exec() Jerry Stuckle <jstucklex@attglobal.net> - 2012-04-15 13:34 -0400
    Re: problems with exec() "J.O. Aho" <user@example.net> - 2012-04-15 19:43 +0200
      Re: problems with exec() "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2012-04-16 00:16 +0200
        Re: problems with exec() "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2012-04-16 00:22 +0200
          Re: problems with exec() "J.O. Aho" <user@example.net> - 2012-04-16 07:17 +0200
            Re: problems with exec() Une Bévue <unbewusstsein@fai.invalid> - 2012-04-16 10:07 +0200
              Re: problems with exec() "J.O. Aho" <user@example.net> - 2012-04-16 19:29 +0200
                Re: problems with exec() Une Bévue <unbewusstsein@fai.invalid> - 2012-04-18 15:44 +0200
                  Re: problems with exec() "J.O. Aho" <user@example.net> - 2012-04-18 18:02 +0200
                    Re: problems with exec() Une Bévue <unbewusstsein@fai.invalid> - 2012-04-18 19:43 +0200
                      Re: problems with exec() "J.O. Aho" <user@example.net> - 2012-04-18 20:37 +0200
                        Re: problems with exec() Une Bévue <unbewusstsein@fai.invalid> - 2012-04-18 23:31 +0200
    Re: problems with exec() Kim André Akerø <kimandre@nospambetadome.com> - 2012-04-16 13:27 +0200
      Re: problems with exec() "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2012-04-16 14:43 +0200

#5530 — problems with exec()

Hi.

I have an interesting problem and I cannot figure out what the problem 
might be.

This does not  produce any output:

$response = exec('ifconfig');
echo $response[0];

Although when I try other commands, I get a response on the screen. So I 
don't get what's so special about ifconfig.

Could anyone help please?

7segment

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#5531

Sorry this was the code I wanted to cite:

$response = exec('ifconfig');
echo $response;

On Sun, 15 Apr 2012 11:37:23 -0500, 7segment wrote:

> Hi.
> 
> I have an interesting problem and I cannot figure out what the problem
> might be.
> 
> This does not  produce any output:
> 
> $response = exec('ifconfig');
> echo $response[0];
> 
> Although when I try other commands, I get a response on the screen. So I
> don't get what's so special about ifconfig.
> 
> Could anyone help please?
> 
> 7segment

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#5532

On 4/15/2012 12:47 PM, 7segment wrote:
> Sorry this was the code I wanted to cite:
>
> $response = exec('ifconfig');
> echo $response;
>
> On Sun, 15 Apr 2012 11:37:23 -0500, 7segment wrote:
>
>> Hi.
>>
>> I have an interesting problem and I cannot figure out what the problem
>> might be.
>>
>> This does not  produce any output:
>>
>> $response = exec('ifconfig');
>> echo $response[0];
>>
>> Although when I try other commands, I get a response on the screen. So I
>> don't get what's so special about ifconfig.
>>
>> Could anyone help please?
>>
>> 7segment
>

Do you have permission to run ifconfig?  Normally the web server does 
not have nearly enough permissions to reconfigure the network adapters 
(which is as it should be).

-- 
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

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#5533

7segment wrote:
> Hi.
>
> I have an interesting problem and I cannot figure out what the problem
> might be.
>
> This does not  produce any output:
>
> $response = exec('ifconfig');
> echo $response;
>
> Although when I try other commands, I get a response on the screen. So I
> don't get what's so special about ifconfig.
>
> Could anyone help please?

ifconfig usually residence in /sbin (some GNU/Linux distribution are in the 
migration path of moving it to /usr/sbin), this directory  is never in a 
normal users or a daemon users $PATH, so you need to give the whole path to 
this binary to be able to run it.

By default the file is executional by all users, but someone may have changed 
permissions or setup ACL rules with for example SELinux.




-- 

   //Aho

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#5535

Am 15.04.2012 19:43, schrieb J.O. Aho:
> 7segment wrote:
>> Hi.
>>
>> I have an interesting problem and I cannot figure out what the problem
>> might be.
>>
>> This does not  produce any output:
>>
>> $response = exec('ifconfig');
>> echo $response;
>>
>> Although when I try other commands, I get a response on the screen. So I
>> don't get what's so special about ifconfig.
>>
>> Could anyone help please?
> 
> ifconfig usually residence in /sbin (some GNU/Linux distribution are in the migration
> path of moving it to /usr/sbin), this directory  is never in a normal users or a
> daemon users $PATH, so you need to give the whole path to this binary to be able to
> run it.
> 
> By default the file is executional by all users, but someone may have changed
> permissions or setup ACL rules with for example SELinux.
> 

I can tell that on opensuse it it not executable by normal users.

/Str.

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#5536

Am 16.04.2012 00:16, schrieb M. Strobel:
> Am 15.04.2012 19:43, schrieb J.O. Aho:
>> 7segment wrote:
>>> Hi.
>>>
>>> I have an interesting problem and I cannot figure out what the problem
>>> might be.
>>>
>>> This does not  produce any output:
>>>
>>> $response = exec('ifconfig');
>>> echo $response;
>>>
>>> Although when I try other commands, I get a response on the screen. So I
>>> don't get what's so special about ifconfig.
>>>
>>> Could anyone help please?
>>
>> ifconfig usually residence in /sbin (some GNU/Linux distribution are in the migration
>> path of moving it to /usr/sbin), this directory  is never in a normal users or a
>> daemon users $PATH, so you need to give the whole path to this binary to be able to
>> run it.
>>
>> By default the file is executional by all users, but someone may have changed
>> permissions or setup ACL rules with for example SELinux.
>>
> 
> I can tell that on opensuse it it not executable by normal users.
> 

Correct is: on suse it is not found on the path. When called with path /sbin/ifconfig
in a shell it outputs the NIC configuration. When called like that it outputs nothing:

php > $a = exec('/sbin/ifconfig');
php > echo $a;
php > var_dump($a);
string(0) ""


/Str.

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#5537

M. Strobel wrote:
> Am 16.04.2012 00:16, schrieb M. Strobel:
>> Am 15.04.2012 19:43, schrieb J.O. Aho:
>>> 7segment wrote:
>>>> Hi.
>>>>
>>>> I have an interesting problem and I cannot figure out what the problem
>>>> might be.
>>>>
>>>> This does not  produce any output:
>>>>
>>>> $response = exec('ifconfig');
>>>> echo $response;
>>>>
>>>> Although when I try other commands, I get a response on the screen. So I
>>>> don't get what's so special about ifconfig.
>>>>
>>>> Could anyone help please?
>>>
>>> ifconfig usually residence in /sbin (some GNU/Linux distribution are in the migration
>>> path of moving it to /usr/sbin), this directory  is never in a normal users or a
>>> daemon users $PATH, so you need to give the whole path to this binary to be able to
>>> run it.
>>>
>>> By default the file is executional by all users, but someone may have changed
>>> permissions or setup ACL rules with for example SELinux.
>>>
>>
>> I can tell that on opensuse it it not executable by normal users.
>>
>
> Correct is: on suse it is not found on the path. When called with path /sbin/ifconfig
> in a shell it outputs the NIC configuration. When called like that it outputs nothing:
>
> php>  $a = exec('/sbin/ifconfig');
> php>  echo $a;
> php>  var_dump($a);
> string(0) ""

Think the ifconfig makes a bit environment check and wants a shell, use 
shell_exec instead and you will see the output.


-- 

   //Aho

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#5539

Le 16/04/2012 07:17, J.O. Aho a écrit :
>>
>> php>  $a = exec('/sbin/ifconfig');
>> php>  echo $a;
>> php>  var_dump($a);
>> string(0) ""
>
> Think the ifconfig makes a bit environment check and wants a shell, use
> shell_exec instead and you will see the output.
>

On Ubuntu 11.10, this works very well :
$lines=explode("\n", shell_exec('/sbin/ifconfig'));
foreach ($lines as $line) {
   echo "$line<br />";
}

may be the prob i had creating an ssh tunnel comes also from the 
difference between "exec" and "shell_exec" ?

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#5546

Une Bévue wrote:
> Le 16/04/2012 07:17, J.O. Aho a écrit :
>>>
>>> php> $a = exec('/sbin/ifconfig');
>>> php> echo $a;
>>> php> var_dump($a);
>>> string(0) ""
>>
>> Think the ifconfig makes a bit environment check and wants a shell, use
>> shell_exec instead and you will see the output.
>>
>
> On Ubuntu 11.10, this works very well :
> $lines=explode("\n", shell_exec('/sbin/ifconfig'));
> foreach ($lines as $line) {
> echo "$line<br />";
> }
>
> may be the prob i had creating an ssh tunnel comes also from the difference
> between "exec" and "shell_exec" ?

I suspect it could have the same issue, try to use shell_exec and let us know 
if it works.

-- 

   //Aho

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#5560

Le 16/04/2012 19:29, J.O. Aho a écrit :
> I suspect it could have the same issue, try to use shell_exec and let us
> know if it works.

Unfortunately, not.
i suspect because the line :

$cmd = ssh -L 63333:localhost:5432 -f yt@iMac -N

is without password for the user 'yt' not for php being of user 
'www_data' on Ubuntu.

Nevertheless i got that pgsql db working remotly after editing pg_hba.conf.

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#5561

Une Bévue wrote:
> Le 16/04/2012 19:29, J.O. Aho a écrit :
>> I suspect it could have the same issue, try to use shell_exec and let us
>> know if it works.
>
> Unfortunately, not.
> i suspect because the line :
>
> $cmd = ssh -L 63333:localhost:5432 -f yt@iMac -N
>
> is without password for the user 'yt' not for php being of user 'www_data' on
> Ubuntu.
>
> Nevertheless i got that pgsql db working remotly after editing pg_hba.conf.

Otherwise, you can copy the public key to the www-data users ~/.ssh and the 
ssh would have worked. Of course you could have setup a cron job instead which 
would recreated the tunnel each time it went down.
Of course those two solutions aren't as good as using the proper method.

-- 

   //Aho

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#5562

Le 18/04/2012 18:02, J.O. Aho a écrit :
>
> Otherwise, you can copy the public key to the www-data users ~/.ssh and
> the ssh would have worked. Of course you could have setup a cron job
> instead which would recreated the tunnel each time it went down.
> Of course those two solutions aren't as good as using the proper method.

ok, thanks.
In fact i've used the ssh tunnel because it was the simplest :
create the tunnel and use the psql server as if it is local.

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#5563

Une Bévue wrote:
> Le 18/04/2012 18:02, J.O. Aho a écrit :
>>
>> Otherwise, you can copy the public key to the www-data users ~/.ssh and
>> the ssh would have worked. Of course you could have setup a cron job
>> instead which would recreated the tunnel each time it went down.
>> Of course those two solutions aren't as good as using the proper method.
>
> ok, thanks.
> In fact i've used the ssh tunnel because it was the simplest :
> create the tunnel and use the psql server as if it is local.

*nods*
In a way it's easy, but at the same time you get something more that can fail 
and it can be looking strange in the error messages when the ssh tunnel is 
still there while the other end of the tunnel don't work, seen issues with 
that at a company I used to work for.

I haven't followed your thread, but you know that user A can setup the tunnel 
and user B can use it.



-- 

   //Aho

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#5567

On 18/04/12 20:37, J.O. Aho wrote:
> I haven't followed your thread, but you know that user A can setup the
> tunnel and user B can use it.

Yes, thanks, in fact i used the tunnel only to start with by the time i 
setup pg_hba.conf.

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#5541

På Sun, 15 Apr 2012 18:37:23 +0200, skrev 7segment <7segment@nowhere.com>:

> Hi.
>
> I have an interesting problem and I cannot figure out what the problem
> might be.
>
> This does not  produce any output:
>
> $response = exec('ifconfig');
> echo $response[0];
>
> Although when I try other commands, I get a response on the screen. So I
> don't get what's so special about ifconfig.
>
> Could anyone help please?

Based on your corrected code in your own reply, which lists the second  
line as "echo $response;", I can see what you problem would be.

Even if you're allowed to run this particular command from your PHP  
script, the return value of exec() is always the LAST line of the command  
output. On my system, the last line of the "ifconfig" command is always  
blank, which is what $response in your code example would contain. Try  
instead to do it like this (and, preferrably, include the full path of  
ifconfig):

exec('/sbin/ifconfig', $response); // $response is an array
echo implode('\n', $response);

-- 
Kim André Akerø
- kimandre@NOSPAMbetadome.com
(remove NOSPAM to contact me directly)

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#5543

Am 16.04.2012 13:27, schrieb Kim André Akerø:
> På Sun, 15 Apr 2012 18:37:23 +0200, skrev 7segment <7segment@nowhere.com>:
> 
>> Hi.
>>
>> I have an interesting problem and I cannot figure out what the problem
>> might be.
>>
>> This does not  produce any output:
>>
>> $response = exec('ifconfig');
>> echo $response[0];
>>
>> Although when I try other commands, I get a response on the screen. So I
>> don't get what's so special about ifconfig.
>>
>> Could anyone help please?
> 
> Based on your corrected code in your own reply, which lists the second line as "echo
> $response;", I can see what you problem would be.
> 
> Even if you're allowed to run this particular command from your PHP script, the
> return value of exec() is always the LAST line of the command output. On my system,
> the last line of the "ifconfig" command is always blank, which is what $response in
> your code example would contain. Try instead to do it like this (and, preferrably,
> include the full path of ifconfig):

Very convincing, thank you. I was about to test why ifconfig would need the shell
environment...

/Str.

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