If I'm already running code in a background by exec
and inside it I call for another exec.
Is it possible ?
If so, does it need special permissions ?
The error I have (and I suspect nested exec in it):
exec() has been disabled for security reasons
Regular exec enabled and works.
Technically it's possible to have an exec in your exec, but it looks like you're using different configurations. Usually PHP has to different sets (Apache and CLI) of php.ini files (which might be configured to disable the exec function at all.
I assume your first exec call is coming from apache, which then calls a php script on the command line. The second seems to have a different configuration and therefore disallow the exec-call. So best have a look at /etc/php, if there are different php.inis set.
Can you please share your code.... It is difficult to determinate if there is any problem without looking the code.
If you have access to use exec it should not be a problem to use exec inside another exec.
This is your localhost or a shared hosting? Most shared hosting disable exec for security reasons.
Related
Let's say I have an executable PHP file that is usually run like this:
php somefile -d someParameter --verbose
How can I run this file using an existing PHP script? I am not looking into doing shell_exec('php somefile -d someParamter --verbose') since many webhosts disallow the use of shell_exec.
I am thinking something like using require('somefile') and then magically passing in the parameters needed for the command to run.
If your hosting does not allow shell_exec nor exec then you cannot run any external binaries. And it's always common practice to sandbox vhost content so if they would not block shell_exec/exec you may be hosted from noexec mounted volume anyway, so sidede "loaded" binaries would not work either. If you need to run 3rd party binaries, VPS is the way to go, not shared hosting.
Search on DDG and in here didn't get any interesting results. I've heard they're different, but I want to know what makes them different and what advantage is there in having two different configurations ?
EDIT : Yes, I am running them both from the CLI.
phpinfo() is a language function that will display its output regardless of whether the script that it's executed in is called through the web SAPI or from CLI;
php -i is purely a command line switch to get information about PHP from the command line.
Why different configurations for web sapi and for CLI? Because you might have different requirements; often devs will run long command line scripts and don't want the web sapi timeout applied, similarly with memory settings; and max file/post size ini settings are meaningless for CLI, so why bother having them in the cli ini file when they're only needed for the web?
Depending on your server distribution, there may be separate php.ini
files for the command line and web server.
Source:
Pro PHP
Patterns, Frameworks, Testing and More
By Kevin McArthur
https://books.google.pl/books?id=CpUhDavmgSMC&pg=PT410&lpg=PT410&dq=%22php+-i+command%22&source=bl&ots=iljmNZ96ZU&sig=iRrX8_UjJWiOzlLtRz0zwJOtQJc&hl=pl&sa=X&ved=0ahUKEwicoq6NrsLLAhVjQZoKHeSSA8wQ6AEIPDAE#v=onepage&q=%22php%20-i%22&f=false
php -i gives you the same info you got using phpinfo() but:
can use a different set of INI files than your web server (so you can different values for some configuration parameters)
it formats the data in a console-friendly way (no html tags, for example)
Edit:
don't digged the sources, but I can bet both uses the same code to extract their info .. in other words php -i is "calling phpinfo()" in a console-aware way and context
I am wondering if a PHP script can be executed from a shell command line.
Does a script executed from shell have the exact functionality if executed from the browser? or is there a difference in coding.
Is it better to run a script from shell for performance and also is it better to run it from windows or unix/linux
I am asking all these questions because, I am suppose to develop a PHP script that can fetch some data from http headers of some urls listed in a MySQL db and then store the data in the database.
Can you guys point me to the right direction please, Do I need ubuntu, or is there a shell that can run php from windows? all I have at the moment installed is WAMP, which has mysql, php and apache server.
I am sorry for being a novice.
thanks for your kind help
I am wondering if a PHP script can be executed from a shell command line.
Yes
Does a script executed from shell have the exact functionality if executed from the browser? or is there a difference in coding.
It won't have $_REQUEST and friends populated, and $_SERVER won't have server information in it.
Is it better to run a script from shell for performance
Maybe. It avoids the overhead of runnning a webserver. It stops you having cached versions in memory for faster re-execution.
and also is it better to run it from windows or unix/linux
Benchmark it.
I am asking all these questions because, I am suppose to develop a PHP script that can fetch some data from http headers of some urls listed in a MySQL db and then store the data in the database.
There doesn't seem to be any need to involve a web server for that.
Can you guys point me to the right direction please, Do I need ubuntu, or is there a shell that can run php from windows?
The standard Windows shell can.
all I have at the moment installed is WAMP, which has mysql, php and apache server.
You'll need the command line version of PHP. I've no idea if WAMP includes it or not.
I am wondering if a PHP script can be executed from a shell command line.
It's possible either by executing:
$ php -f your_script.php
Or by inserting #/usr/bin/env php into the first line of the script and by making it executable.
$ head -n 1 your_sript.php
#/usr/bin/env php
$ chmod +x your_script.php
$ ./your_script.php
Note: this example only works on UNIX systems.
Does a script executed from shell have the exact functionality if executed from the browser? or is there a difference in coding.
You can use the same Syntax/Functions etc. The only difference is that there are command line arguments in $argv and some other values in the $_SERVER variable.
Is it better to run a script from shell for performance and also is it better to run it from windows or unix/linux.
That doesn't really matter. For your usecase you don't really need a webserver, and a full featured GUI. The advantage of having a command line tool is, you can combine your program with other program available like grep etc.
Can you guys point me to the right direction please, Do I need ubuntu, or is there a shell that can run php from windows?
You don't need ubuntu, you can also execute a shell script from windows. The PHP executable is located in the %PATH%. This question will help you in order to do this: https://superuser.com/questions/284342/what-are-path-and-other-environment-variables-and-how-can-i-set-or-use-them
Then simply open cmd.exe and execute a script using php -f your_script.php
Yes, PHP can be run from command line.
No, there aren't any differences in coding.
The only difference is that it's not Apache running the script, but the user you are currently logged in as. That could mean different privileges on certain maps and folders.
Yes you can execute PHP from the command line using:
/path/to/php.exe /path/to/script.php
The main difference is that it doesn't run through Apache, so you won't have things that rely on it (like some $_SERVER data).
Also it won't be subject to timeouts on the command line, unless you have a PHP limit set.
Take a look at http://php.net/manual/en/features.commandline.php for more info.
I have a (possibly dumb) question.
I have a script made in php, constructed for cli usage. Works fine when I run it from the command line, no problem there. The problem is that the site I'm working on has ssh restrictions on the hosting server and I cannot ssh there to run it. Hence my question: how can I run the script from another php that is web-accessible? Already tried with exec(), system(), etc.
The main problem is that I need he $_SERVER['SHELL'] variable set, and when the call is comming from a web browser of course php doesn't set it.
Any ideeas will be greatly apreciated, thanx.
There are many possibilities why exec() and related function calls are not working for you.
Your webhost does not have PHP-CLI installed. Just a webserver module
You need to use the full path to the php binary for lack of a decent shell environment. E.g. /usr/bin/php <script> instead of php <script>.
Your webhost has installed PHP-CLI on a non-standard path (e.g. /usr/local/bin/php, or /opt/php5/php)
The webserver user does not have rights to access the php binary
Et cetera..
maybe update the php script to be both an include and a cli script.
use
__FILE__
to check if it's a file, then read the params. otherwise do nothing.
and as an include just call the function you want directly.
From inside a PHP program I want to know the location of the binary executing it. Perl has $^X for this purpose. Is there an equivalent in PHP?
This is so it can execute a child PHP process using itself (rather than hard code a path or assume "php" is correct).
UPDATE
I'm using lighttpd + FastCGI, not Apache + mod_php. So yes, there is a PHP binary.
eval/include is not a solution because I'm spawning a server which has to live on beyond the request.
Things I've tried and don't work:
$_SERVER['_'] looks like what I want from the command line but its actually from an environment variable set by the shell of the last executed program. When run from a web server this is the web server binary.
which php will not work because the PHP binary is not guaranteed to be the same one as is in the web server's PATH.
Thanks in advance.
The PHP_BINDIR constant gives you the directory where the php binary is
Yeah, $_SERVER['_'] is what you're talking about, or as near as exists. The reason you're getting a Web server binary when it's run from the web is that /usr/bin/php has nothing to do with the Web server's execution; what it's running is a separate SAPI. There's nothing from the web PHP instance to point to /usr/bin/php because there's no reason for there to be.
The PHP_BINDIR constant is probably the easiest thing to use; the next best thing I could come up with is basically re-creating that bindir path from the extension_dir configuration setting:
$phpbin = preg_replace("#/lib(64)?/.*$#", "/bin/php", ini_get("extension_dir"));
It has a regex in it, so it feels more like your native perl(!) but otherwise is not especially optimal.
In PHP5.4 you can use the PHP_BINARY constant, it won't work via mod_php or similar but will via CGI etc.
For earlier versions of PHP readlink('/proc/self/exe'); will probably be fine, again it won't work via mod_php.
Depending on the way php is installed you CANT find the php executable.
if php is running as a module for the webserver like apache module, then there is no binary you can call.
you can take a look into php_info() it lists everything.
may also the path to php. within that path you can assume a php binary.
but why do you want to call a extra process?
you can execute other php files by include command or eval.
there is no reason to spawn a new process.
what about:
<?php
exec("which php");
?>
But, it's unix/linux only:D
I've been looking for the php7 executable on my mac (OSX El Capitan) in order to configure and install xdebug (needed to find the right version of phpize to run). None of the solutions I found worked for me, so I just ended out searching for it:
find / -name php -print
I knew (from phpinfo()) that I was running php7, so I was able to infer the correct directory from the options presented by find.