I already said that I was new to exec() function. After doing some more digging, I came upon 2>&1 which needs to be added at the end of command in exec().

Thanks @mattosmat for pointing it out in the comments too. I did not try this at once because you said it is a Linux command, I am on Windows.

So, what I have discovered, the command is actually executing in the back-end. That is why I could not see it actually running, which I was expecting to happen.

For all of you, who had similar problem, my advise is to use that command. It will point out all the errors and also tell you info/details about execution.

exec('some_command 2>&1', $output);
print_r($output);  // to see the response to your command

Thanks for all the help guys, I appreciate it ;)

The question is a bit old, but for those who experience this problem can try to set the environment variables of direct on the server. PHP uses the putenv () function.

Example:// Set Variable Enviromental

$JAVA_HOME = "/usr/lib/jvm/java-8-oracle"; 
$ANDROID_HOME = "/opt/android-sdk-linux";
$PATH="$JAVA_HOME/bin:/usr/local/bin:/usr/bin:/bin:$ANDROID_HOME/platform-tools:$ANDROID_HOME/tools:$ANDROID_HOME/build-tools/24.0.0-preview";

putenv ("JAVA_HOME = $JAVA_HOME"); 
putenv ("PATH = $PATH");

I would double check that you are running the command as the same user from the command line and your php script. That may be the problem. exec('whoami')

You said you had a script that starts your php script it should be the same user as that.

You might also want to running a simpler exec command to see if that will work first.

Other things to try:

1. Try checking stderr output exec('ls /tmp 2>&1', $out); This will redirect standard error to standard out so you get both.
2. Try using php's shell_exec() which will invoke a shell just like when you are running from the command line(eg. bash). shell_exec('ls /tmp 2>&1 >> /tmp/log') should even put all output into a log file.
3. I don't think this will help you but it is something to try if all else fails, set it as a background process and see if it completes. exec('nohup php process.php > process.out 2> process.err < /dev/null &'). The & will set the command to run in the background and let the script continue.

Good Luck

The Apache’s user www-data need to be granted privileges to execute certain applications using sudo.

1. Run the command sudo visudo. Actually we want to edit the file in etc/sudoers.To do that, by using sudo visudo in terminal ,it duplicate(temp) sudoers file to edit.
2. At the end of the file, add the following ex:-if we want to use command for restart smokeping and php command for another action in your question,

www-data ALL=NOPASSWD: /etc/init.d/smokeping/restart, usr/bin/php

(This is assuming that you wish to run restart and php commands using super user (root) privileges.And you use php command in usr/bin/ path )

However, if you wish to run every application using super user privileges, then add the following instead of what’s above.You might not want to do that, not for ALL commands, very dangerous.

www-data ALL=NOPASSWD: ALL

3.After edit the sudoers file(by visudo we edit the temp file of sudoers so save and quit temp file(visudo) to write in sudoers file.(wq!)

4.That’s it, now use exec() or shell_exec in the following manner inside your xxx.phpscript.keep remember to use sudo before the command use in the php script.

ex:-

exec ("sudo /etc/init.d/smokeping restart 2>&1");

or

shell_exec("sudo php -v"); 

So in your problem,add the commands that you wish to use in to the step no (2.) as I add and change your php script as what you want.

here is the same problem as yours https://stackoverflow.com/a/22953339/1862107

Nailing down exec() problems:

I'd suggest you to check what exec() is giving back:

echo exec(...);

Sure, it may happen that ffmpeg is simply not in your PATH. In this case exec() will clearly state about this, and you might need to provide the absolute path to ffmpeg, i.e.:

Linux:

exec("/path/to/ffmpeg ...");

Windows:

exec("c:\\path\\to\\ffmpeg ...");

Background task:

Other concern is that ffmpeg might run for a pretty long time, which might lead to a timeout. To avoid this problem you can execute ffmpeg in a background by adding & at the end of your command, or, for Windows, adding cmd /C in front of your actual command:

Linux:

exec("ffmpeg -i test.mp4 -ab 96k -b:v 700k -ar 44100 -s 640x480 test.webm &");

Windows:

exec("cmd /C ffmpeg -i test.mp4 -ab 96k -b:v 700k -ar 44100 -s 640x480 test.webm");

In this case exec() will return immediately, leaving ffmpeg() running in the background. ffmpeg() process will terminate as soon as it has done it's execution. But sure, you need to implement some sort of monitoring mechanism, if you want to notify the user that conversion is completed and converted file is available for download.

If you say it works on the terminal and not on apache then apache's php.ini file may be disabling the use of shell_exec().

See http://www.php.net/manual/en/ini.core.php#ini.disable-functions

Your apache's php.ini file may look something like

disable_functions=exec,passthru,shell_exec,system,proc_open,popen

Remove shell_exec from this list and restart the web server, although this is a security risk and I don't recommend it.

PHP is (thankfully!) not running as the root user, so it does not have privileges to run apt install. The suid bit is ignored on shell scripts, so setting that bit on your shell script is not a solution, either.

If you really really want to give PHP the privileges to run apt-get as the root user (and please, think really hard about this), you can add an entry to sudoers to allow it to do so, but your command will have to be sudo apt-get [...].

Running a script through a web based front-end via a sudo grant is ill-advised, because if somebody somehow figures out a way to edit that file, now they can do whatever they want to do on your system as the superuser by having PHP do it for them.

Add 2>&1 to the end of your command to redirect errors from stderr to stdout. This should make it clear what's going wrong.

By the looks of it your PATH variable only includes /bin. This only allows you to run executables within that directory. There are a few ways to fix this.

Method 1: Configure the web server environment varibles

If you are running apache, you can simply edit /etc/apache2/envvars to include a PATH varibale definition. Edit the file and add a new line to the bottom (if it doesn't already exist):

# /etc/apache2/envvars
...

export PATH="/bin:/usr/local/bin"

Method 2: Configure the PATH for the user

Alternatively, if you are running the web server as a user other than a service user, that user may not have their PATH properly configured. This is as simple as changing their environment variables for the user and the web server will inherit it (unless defined otherwise in the web server's configuration).

First step is figure out which user your web server is running as. If you don't know, you can check list the running processes to find the user. This can be accomplished by running the following command:

ps aux|grep {webserver}|grep -v grep Where {webserver} is replaced with the web server you are currently running. (apache/httpd, nginx)

Alternatively, you can check in of the following config files:

• /etc/httpd/conf/httpd.conf - CentOS Apache
• /etc/apache2/apache2.conf - Ubuntu/Debian Apache
• /etc/nginx/nginx.conf - nginx config

(There are many other possible configurations, but these are the most common)

Once you've found out which user you're running as, you will need to then set the PATH variable for that user. This could be as simple as exporting the PATH in their home bash configuration. This could be /home/bob/.bashrc for example. Service users without a home will be different however.

Method 3: Declare the PATH within your PHP script

You can manually specify the PATH variable within your PHP script. This can be accomplished by adding the following line to your script:

<?php

putenv('PATH=/bin:/usr/local/bin');
...

You will need to change the PATH to suit your needs, and it will need to be declared before you call shell_exec().

This method isn't preferred as you will need to specify this for each PHP script you execute that makes use of the shell_exec() call to binaries outside of /bin, but it is a quick one off solution that will work.

More importantly, you are writing code that is not portable and is dependent on a specific system. This is bad coding practice and is not recommended/frowned upon.