it's a bit complicated. :-) I have a website written in PHP that needs to call an external program written in .NET, running under Mono. It calls the program with:
/path/mono /path/executable arguments...
as per usual (I also tried to put this into a bash script and call the script itself from PHP).
As far as I can tell, everything is set up as required. Mono itself running all right, executable (or script) with executable rights, owners are all right. The correct setup can also be ascertained from the fact that if I issue the command line above (or call the script mentioned) from a command line on the server (Debian Lenny), everything works perfectly, my executable is executed without error.
But, if PHP calls the same (using exec(), system() or any other variant), I immediately get an exit code of 6 from Mono and my executable is not run at all (in order to test it, I use a "Hello World" executable that does nothing but emits a single output line and returns 0). Compiled without any additional dependency, just a real "Hello Word". It's absolutely sure that this program doesn't return the exit code 6, it must come from Mono but I couldn't find it documented anywhere.
I can call anything else from PHP, so it's not safe mode or any similar restriction that would keep me from executing external programs from PHP.
Thanks for any idea...
Try to execute mono from the command line but with the user running the webserver (www-data or apache).
ej.
#su apache
$/path/to/mono /path/to/program.exe
The common problems that I have using exec is a different environment variables (look if is bash or sh what apache is using), permissions to the user/group of apache, etc.
Related
Is there any reason why I can not complied files in PHP's shell_exec/exec/system function?
Example of something that does work in command line and PHP's shell_exec function:
<?php
$data = shell_exec("ls");
echo $data;
?>
Example of something that does not work in PHP's shell_exec function but will work in command line (I can confirm that):
<?php
$data = shell_exec("./c-compiled-file argv1 argv2 argv3");
echo $data;
?>
Is there anything I can do on my server so this will work? I've looked everywhere and no solutions I found fixed the problem. The compiled file is in the same directory as the PHP script as well, it just won't execute it. Also if you're asking, yes I have tried this with SSH2 and it still will not execute.
Also PHP is not in safe mode and NO functions are disabled.
Some common glitches when executing external commands from PHP that work fine from shell:
Command uses relative paths but PHP is launched from an arbitrary location:
Use getcwd() / chdir() to get/set working directory
PHP and shell run with different user credentials. This is often the case when PHP runs through a web server.
PHP and shell run different commands. Many people call stuff like exec("foo $bar") and doesn't even check what "foo $bar" contains.
No error checking is done. The bare minimum is to capture and print standard output, standard error, status code and, of course, all PHP error messages including warnings and notices.
You can redirect stderr to sdtout
You can use a PHP function that allows to capture more information, such as exec()
The web server is disallowed to execute the command at operating system level.
Lookout for SELinux or similar tools.
Just a guess, but the binary you're trying to execute might not have the proper permissions. Prepeding it with ./ in the command line forces it to execute, but PHP probably strips that for security purposes. Try this:
chmod +x c-compiled-file
You want to use system in the second case, and not shell_exec.
system executes an external program and displays the output.
shell_exec executes a command via shell and returns the complete output as a string.
and for good measure:
exec simply executes an external program.
Furthermore you want to make sure your external program is executable and (though you have stated it, I'll restate this) has execute permissions for the user which is running the web server. You also want to make sure the directory your external program is running in has the ability to write to its directory or /tmp or whatever output directory you have set.
Finally you should always use absolute paths for executing things like this in cron or php or whatever... so don't use ./c-compiled-file argv1 argv2 argv3, but instead use /home/username/c-compiled-file argv1 argv2 argv3 or whatever the full path is.
I am having an issue using the PHP function shell_exec().
I have an application which I can run from the linux command line perfectly fine. The application takes several hours to run, so I am trying to spawn a new instance using shell_exec() to manage better. However, when I run the exact same command (which works on the command line) through shell_exec(), it returns an empty string, and it doesn't look like any new processes were started. Plus it completes almost instantly. shell_exec() is suppose to wait until the command has finished correct?
I have also tried variations of exec() with the same outcome.
Does anyone have any idea what could be going on here?
There are no symbolic links or anything funky in the command: just the path to the application and a few command line parametes.
Some thing with you env
See output of env from cli (command line interface) and php script
Also see what your shell interpreter?
And does script and cli application runs from one user?
If so, se option safe_mode
Make sure the user apache is running on (probably www-data) has access to the files and that they are executable (ls -la). A simple chmod 777 [filename] would fix that.
By default PHP will timeout after 30 sec. You can disable the limit like this:
<?php
set_time_limit(0);
?>
Edit:
Also consider this: http://www.rabbitmq.com/
I have tried calling a windows program several ways and I have gotten the same result each time.
The program opens up on my machine (without a GUI) but never closes each means that the browser is forever loading.
Though when executing the query string manually through the command line prompt the program closes. Not only that, but the program doesn't actually execute
(it is just launched i.e. there aren't any results).
I just want to know the proper way of starting a program with switches through PHP.
Here is the query string that works (closes the program after executing):
"C:\Program Files (x86)\Softinterface, Inc\Convert PowerPoint\ConvertPPT.exe" /S
"C:\Users\Farzad\Desktop\upload\test.ppt" /T "C:\Users\Farzad\Desktop\upload\test.png" /C 18
If the program never closes, then PHP can't return a value from exec(). The program must close. Chances are there is a problem accessing your files on your desktop in this manner. It will be executed with whatever permissions the webserver has defined.
http://php.net/manual/en/function.exec.php
You might consider the advanced functionality of proc_open(). It will give you access to all the necessary pipes, but I don't think that will help you in this situation.
If the target directory on your Windows machine is C:\Program Files (x86)\Softinterface, Inc\Convert PowerPoint\ConvertPPT.exe, you need to double-quote the directories that have space character within them.
To translate it into php terms, it should be like this:
$directory = 'C:\"Program Files (x86)"\"Softinterface, Inc"\"Convert PowerPoint"\ConvertPPT.exe';
$command = $directory . ' enter your arguments here';
exec($command, $output, $return_var);
// if $return_var == 0, you hit the jackpot.
The physical directory where your Windows desktop is stored belongs to your user profile folder. That means that other users (including the one Apache runs as, which is typical "Local System") won't have the appropriate permissions to read and write files on it. While you can adjust your Apache set-up to make it run with your own user, Farzad, it's more common to put web applications in an entirely different directory tree. It may happen that ConvertPPT.exe just stalls because it's trying to write a file at a location where it's not allowed. I suggest you create a top folder directory and make sure it's world-writeable (once finished, you can tighten these permissions if you like).
Once you discard (or confirm) that the issue is caused by lack of appropriate credentials, make sure you are escaping your command and arguments properly. See this link:
http://es2.php.net/manual/en/function.exec.php#101579
One more thing you can try is to close PHP sessions before issuing the call to exec():
http://es2.php.net/manual/en/function.exec.php#99781
You have probably run into this bug: http://bugs.php.net/bug.php?id=44994
which has been bothering me for ages, even today, on PHP 5.3.5.
It seems like there is some kind of deadlock between the error output of the program and the apache error log file handle into which the program is redirected to write its stderr output, making the program be stuck for ever until the apache processes are killed.
Also, when using passthru, or system, or the backtick operator, there's an intermediary "cmd.exe" process that is used to run the program in an invisible console, and I have seen this cmd process getting stuck without even running the program.
I don't really have a solution as of now, and it seems the bug, even though reproduced by many people, hasn't been resolved.
When I call /usr/local/bin/pdftk from PHP in Apache (via shell_exec(), exec(), system(), etc.), it returns the SYNOPSIS message as expected.
When I call /usr/local/bin/pdftk input.pdf fill_form input.fdf output output.pdf flatten via shell_exec(), nothing returns.
When I copy and paste the exact same string to the same path in the shell (as the apache user), the output.pdf file is generated as expected.
Moving the pdftk command into a PHP shell script (shebang is #!/usr/bin/php) and executing it with php script.php works perfectly.
Calling that shell script (with its stderr redirected to stdout) from PHP in Apache (via shell_exec(script.php);) results in this line:
sh: line 1: 32547 Segmentation fault /usr/local/bin/pdftk input.pdf fill_form input.fdf output output.pdf flatten 2>&1
Whenever I run the script from the command line (via PHP or directly), it works fine. Whenever I run the script through PHP via Apache, it either fails without any notification or gives the SegFault listed above.
It's PHP 4.3.9 on RHEL4. Please don't shoot me. I've set memory to 512M with ini_set() and made sure that the apache user had read/write to all paths (with fopen()) and by logging in as apache ...
Just went and checked /var/log/messages to find this:
Oct 4 21:17:58 discovery kernel: audit(1286241478.692:1764638):
avc: denied { read } for pid=32627 comm="pdftk" name="zero"
dev=tmpfs ino=2161 scontext=root:system_r:httpd_sys_script_t
tcontext=system_u:object_r:zero_device_t tclass=chr_file
NOTE: Disabling SELinux "fixed" the problem. Has this moved into a ServerFault question? Can anybody give me the 30 second SELinux access controls primer here?
php-cli & php-cgi (or the module, depends on what your server uses) are different binaries. They don't even have to share the same version to live happily side by side on your server. They also may not share the same configuration. Increasing memory usually does nothing to help Segfaults. Points to check:
Are they the same version?
Do they have the same settings (consult the *.ini locations loaded in the phpinfo(); output, and possibly the whole output itself), if not: try what happens if you alter the one for your webserver to the one for the cli as far as possible.
Segfaults occur more in extensions then in the core afaik, and sometimes seemingly unrelated. Try to disable unneeded extensions one by one to see if the problem goes away.
Still no success? You may want to run apache with gdb, but I have no experience with that, it might tell you something though.
No luck? Recompile either the module of cgi your webserver uses.
It's PHP 4.3.9 on RHEL4. Please don't shoot me.
I feel more sad for you then anger, we're beyond the 5.3 mark, come over, it's a lot more happy here.
I have a program that returns a comma-separated string of numbers after doing some background processing. I intended to run this in symfony using shell_exec; however, all I get is NULL (revealed through a var_dump(). I tried the following debugging steps.
I ran the file (it's a PHP class) through a command-line lime unit test in Symfony - it works and gives the correct result there.
Just to check, I tried a simple command ls -l at the same place to see whether I would get anything. Again, I had the same problem - the var_dump in the browser showed NULL, but it worked through the command line.
What could be the problem? Are there restrictions on running shell_exec() in a browser?
EDIT: Just to clarify, shell_exec() commands work when I run them as standalone php scripts on the web server (for example, by putting them in my document root. They don't seem to be working under the symfony framework, for some reason.
I finally solved it, and it turned out to be something quite simple, and quite unrelated.
The shell command I was running was in this format: face_query -D args. I didn't realize that Apache would be executing PHP as user www-data and thus the program face_query wouldn't be in the PATH (the directory is actually ~/bin). Changing the program name to the full path of the program solved it.
I also gather from this that only commands which www-data has permission to execute can be run. In this case, www-data is in the same group as my user, but it might be a problem otherwise.
Have you tried using exec? Or one of the other variants. I am never sure of which one to use and always lump with exec.
http://uk.php.net/manual/en/function.exec.php
Is your web server running php in safe mode?
Note: This function is disabled when PHP is running in safe mode.
From: http://php.net/manual/en/function.shell-exec.php