| Re: Queuing at job from within php program? [message #175673 is a reply to message #175670] |
Mon, 17 October 2011 20:53   |
Jerry Stuckle
Messages: 2598
Registered: September 2010
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Senior Member |
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On 10/17/2011 2:27 PM, Robert Heller wrote:
> At Mon, 17 Oct 2011 12:47:08 -0400 Jerry Stuckle<jstucklex(at)attglobal(dot)net> wrote:
>
>>
>> On 10/17/2011 11:51 AM, bobm3(at)worthless(dot)info wrote:
>>> On Mon, 17 Oct 2011 11:20:38 -0400, Jerry Stuckle wrote:
>>>
>>>> On 10/17/2011 9:24 AM, bobm3(at)worthless(dot)info wrote:
>>>> > Fellow php'ers;
>>>> >
>>>> > I'm having some difficulty getting this to work: Based on a date/time
>>>> > selected by a user on a web form I would like to use the "at" command
>>>> > to schedule that task.
>>>> >
>>>> > I've tried various php functions (system, exec, passthru) with the same
>>>> > results (return code 1 - which I cannot seem to get the error message
>>>> > from).
>>>> >
>>>> > Here is a sample code snippet:
>>>> >
>>>> > $cmd = "echo \"podcast -c $filename\" | at $hr:$mn $_ampm";
>>>> > passthru("$cmd", $Retcode);
>>>> > echo "$Retcode";
>>>> >
>>>> > returns 1
>>>> >
>>>> > Then I thought that perhaps the 'at' was not reading stdin in this case
>>>> > so I tried a temporary file approach:
>>>> >
>>>> > $cmd = "echo \"podcast -c $filename\"";
>>>> > file_put_contents($filename.tmp, $cmd); passthru("at $_hr:$_mn $_ampm<
>>>> > $filename.tmp", $_RetVal); echo "$_RetVal";
>>>> >
>>>> > This time it returned 2
>>>> >
>>>> > I've got to be misunderstanding this function. So, I thought if any of
>>>> > you skilled readers have had luck with doing something like this you
>>>> > may be willing to share. However, any other suggestions greatly
>>>> > appreciated.
>>>> >
>>>> > Thanks
>>>>
>>>>
>>>> What is actually in $cmd when you execute the passthru command?
>>>>
>>>> What happens when you type this exact output at a command line prompt?
>>>
>>> I've echoed out the contents of $cmd in my testing. It does contain
>>> exactly what is intended:
>>> echo "podcast -c abc123 | at 10:01 am"
>>>
>>> Also, the command I'm trying to execute works perfectly from the CLI with
>>> the same (appropriate) values.
>>>
>>> I'm thinking that there might be a permissions issue but I'm unable to
>>> obtain the error message from the passthru command.
>>>
>>> I suppose next I will try to create a small php script to emulate this
>>> from the CLI and perhaps them I will see the error (if any).
>>>
>>> Thanks
>>
>> OK, when you enter that exactly from the CLI it works? Are you
>> executing it as root or another user?
>>
>> Next: the home directory for the web server will be different than the
>> one from the CLI. Also, the web server will have different permissions.
>> Usually the web server user will not have permission to access the
>> atjobs directory (/var/spool/cron/atjobs on Debian).
>>
>> Try su'ing (or sudo'ing) to the web server's id, change to the web
>> server's root directory and execute the command.
>
> On a *typical* (eg properly secured) LAMP server, the web server would
> be running as the user 'apache' and the apache user's shell will be set
> to '/sbin/nologin'. This means that the web server user cannot login to
> a shell. This implies that you cannot fork() a *shell*:
>
> sauron.deepsoft.com% sudo su apache -l
> This account is currently not available.
>
> In order to run an at command, you need to fork() a shell process.
>
>
It depends on what you're doing. Many web servers allow you to fork a
command, for good reasons. Just because you can execute a command shell
doesn't mean it's not properly secured.
--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex(at)attglobal(dot)net
==================
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