Shell exec php linux

shell_exec

(PHP 4, PHP 5, PHP 7, PHP 8)

shell_exec — Выполнить команду через оболочку и вернуть вывод в виде строки

Описание

Функция идентична оператору с обратным апострофом.

В Windows нижележащий канал открывается в текстовом режиме, что может привести к сбою функции для двоичного вывода. В таком случае попробуйте вместо этого использовать popen() .

Список параметров

Команда, которая будет выполнена.

Возвращаемые значения

Строка ( string ), содержащая вывод выполненной команды, false , если канал не может быть установлен или null в случае возникновения ошибки или отсутствии вывода команды.

Эта функция может вернуть null в двух случаях: если произошла ошибка или если выполняемая команда ничего не выводит. Не пользуйтесь этой функцией, для определения, успешно ли выполнилась команда. Вместо этого используйте exec() , так как она предоставляет возможность проверить код возврата.

Ошибки

Выдаётся ошибка уровня E_WARNING , когда канал не может быть установлен.

Примеры

Пример #1 Пример использования shell_exec()

Смотрите также

• exec() — Выполнить внешнюю программу
• escapeshellcmd() — Экранировать метасимволы командной строки

User Contributed Notes 33 notes

If you’re trying to run a command such as «gunzip -t» in shell_exec and getting an empty result, you might need to add 2>&1 to the end of the command, eg:

Won’t always work:
echo shell_exec(«gunzip -c -t $path_to_backup_file»);

Should work:
echo shell_exec(«gunzip -c -t $path_to_backup_file 2>&1»);

In the above example, a line break at the beginning of the gunzip output seemed to prevent shell_exec printing anything else. Hope this saves someone else an hour or two.

To run a command in background, the output must be redirected to /dev/null. This is written in exec() manual page. There are cases where you need the output to be logged somewhere else though. Redirecting the output to a file like this didn’t work for me:

# this doesn’t work!
shell_exec ( «my_script.sh 2>&1 >> /tmp/mylog &» );
?>

Using the above command still hangs web browser request.

Seems like you have to add exactly «/dev/null» to the command line. For instance, this worked:

# works, but output is lost
shell_exec ( «my_script.sh 2>/dev/null >/dev/null &» );
?>

But I wanted the output, so I used this:

proc_open is probably a better solution for most use cases as of PHP 7.4. There is better control and platform independence. If you still want to use shell_exec(), I like to wrap it with a function that allows better control.

Something like below solves some problems with background process issues on apache/php. It also

public function sh_exec(string $cmd, string $outputfile = «», string $pidfile = «», bool $mergestderror = true, bool $bg = false) <
$fullcmd = $cmd;
if(strlen($outputfile) > 0) $fullcmd .= » >> » . $outputfile;
if($mergestderror) $fullcmd .= » 2>&1″;
if($bg) <
$fullcmd = «nohup » . $fullcmd . » &»;
if(strlen($pidfile)) $fullcmd .= » echo $! > » . $pidfile;
> else <
if(strlen($pidfile) > 0) $fullcmd .= «; echo $$ > » . $pidfile;
>
shell_exec($fullcmd);
>

A simple way to handle the problem of capturing stderr output when using shell-exec under windows is to call ob_start() before the command and ob_end_clean() afterwards, like this:

()
$dir = shell_exec ( ‘dir B:’ );
if is_null ( $dir )
< // B: does not exist
// do whatever you want with the stderr output here
>
else
< // B: exists and $dir holds the directory listing
// do whatever you want with it here
>
ob_end_clean (); // get rid of the evidence 🙂
?>

If B: does not exist then $dir will be Null and the output buffer will have captured the message:

‘The system cannot find the path specified’.

(under WinXP, at least). If B: exists then $dir will contain the directory listing and we probably don’t care about the output buffer. In any case it needs to be deleted before proceeding.

I’m not sure what shell you are going to get with this function, but you can find out like this:

= ‘set’ ;
echo «» ;
?>

On my FreeBSD 6.1 box I get this:

USER=root
LD_LIBRARY_PATH=/usr/local/lib/apache2:
HOME=/root
PS1=’$ ‘
OPTIND=1
PS2=’> ‘
LOGNAME=root
PPID=88057
PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin
SHELL=/bin/sh
IFS=’
‘

Very interesting. Note that the PATH may not be as complete as you need. I wanted to run Ghostscript via ImageMagik’s «convert» and ended up having to add my path before running the command:

= ‘export PATH=»/usr/local/bin/»; convert -scale 25%x25% file1.pdf[0] file2.png 2>&1’ ;
echo «» ;
?>

ALSO, note that shell_exec() does not grab STDERR, so use «2>&1» to redirect it to STDOUT and catch it.

I had trouble with accented caracters and shell_exec.

Executing this command from shell :

/usr/bin/smbclient ‘//BREZEME/peyremor’ -c ‘dir’ -U ‘peyremor%*********’ -d 0 -W ‘ADMINISTRATIF’ -O ‘TCP_NODELAY IPTOS_LOWDELAY SO_KEEPALIVE SO_RCVBUF=8192 SO_SNDBUF=8192’ -b 1200 -N 2>&1

Vidéos D 0 Tue Jun 12 14:41:21 2007
Desktop DH 0 Mon Jun 18 17:41:36 2007

Using php like that :

shell_exec(«/usr/bin/smbclient ‘//BREZEME/peyremor’ -c ‘dir’ -U ‘peyremor%*******’ -d 0 -W ‘ADMINISTRATIF’ -O ‘TCP_NODELAY IPTOS_LOWDELAY SO_KEEPALIVE SO_RCVBUF=8192 SO_SNDBUF=8192’ -b 1200 -N 2>&1»)

Vid Desktop DH 0 Mon Jun 18 17:41:36 2007

The two lines were concatenated from the place where the accent was.

I found the solution : php execute by default the command with LOCALE=C.

I just added the following lines before shell_exec and the problem was solved :

$locale = ‘fr_FR.UTF-8’;
setlocale(LC_ALL, $locale);
putenv(‘LC_ALL=’.$locale);

Just adapt it to your language locale.

Here is a easy way to grab STDERR and discard STDOUT:
add ‘2>&1 1> /dev/null’ to the end of your shell command

For example:
= shell_exec ( ‘ls file_not_exist 2>&1 1> /dev/null’ );
?>

Here is my gist to all:

function execCommand($command, $log) <

if (substr(php_uname(), 0, 7) == «Windows»)
<
//windows
pclose(popen(«start /B » . $command . » 1> $log 2>&1″, «r»));
>
else
<
//linux
shell_exec( $command . » 1> $log 2>&1″ );
>

On Windows, if shell_exec does NOT return the result you expected and the PC is on an enterprise network, set the Apache service (or wampapache) to run under your account instead of the ‘Local system account’. Your account must have admin privileges.

To change the account go to console services, right click on the Apache service, choose properties, and select the connection tab.

How to get the volume label of a drive on Windows

function GetVolumeLabel ( $drive ) <
// Try to grab the volume name
if ( preg_match ( ‘#Volume in drive [a-zA-Z]* is (.*)\n#i’ , shell_exec ( ‘dir ‘ . $drive . ‘:’ ), $m )) <
$volname = ‘ (‘ . $m [ 1 ]. ‘)’ ;
> else <
$volname = » ;
>
return $volname ;
>

print GetVolumeLabel ( «c» );

?>

Note: The regular expression assumes a english version of Windows is in use. modify it accordingly for a different localized copy of Windows.

I have PHP (CGI) and Apache. I also shell_exec() shell scripts which use PHP CLI. This combination destroys the string value returned from the call. I get binary garbage. Shell scripts that start with #!/usr/bin/bash return their output properly.

A solution is to force a clean environment. PHP CLI no longer had the CGI environment variables to choke on.

// Binary garbage.
$ExhibitA = shell_exec ( ‘/home/www/myscript’ );

// Perfect.
$ExhibitB = shell_exec ( ‘env -i /home/www/myscript’ );

?>

— start /home/www/myscript
#!/usr/local/bin/phpcli
echo( «Output.\n» );

Be careful as to how you elevate privileges to your php script. It’s a good idea to use caution and planing. It is easy to open up huge security holes. Here are a couple of helpful hints I’ve gathered from experimentation and Unix documentation.

Things to think about:

1. If you are running php as an Apache module in Unix then every system command you run is run as user apache. This just makes sense.. Unix won’t allow privileges to be elevated in this manner. If you need to run a system command with elevated privileges think through the problem carefully!

2. You are absolutely insane if you decide to run apache as root. You may as well kick yourself in the face. There is always a better way to do it.

3. If you decide to use a SUID it is best not to SUID a script. SUID is disabled for scripts on many flavors of Unix. SUID scripts open up security holes, so you don’t always want to go this route even if it is an option. Write a simple binary and elevate the privileges of the binary as a SUID. In my own opinion it is a horrible idea to pass a system command through a SUID— ie have the SUID accept the name of a command as a parameter. You may as well run Apache as root!

As others have noted, shell_exec and the backtick operator (`) both return NULL if the executed command doesn’t output anything.

This can be worked around by doing anything like the following:

Here we’re simply outputting blank whitespace if the command succeeds — which satisfies this slightly strange issue. From there, you can trim() the command output etc.

it took me a heck of a lot of head banging to finally solve this problem so I thought that I would mention it here.

If you are using Eclipse and you try to do something like

= shell_exec ( «php -s $File » ); //this fails
?>

it will always fail when run inside of the Eclipse debugger. This happens on both Linux and Windows. I finally isolated the problem to changes that Eclipse makes to the environment when debugging.

The fix is to force the ini setting. If you don’t need an ini then -n is sufficient.

= shell_exec ( «php -n -s $File » ); //this works
?>

Of course if you run it outside of the debugger then it works fine without the -n. You may want to use a debug flag to control this behavior.

shell_exec is extremely useful as a substitute for the virtual() function where unavailable (Microsoft IIS for example). All you have to do is remove the content type string sent in the header:

This works fine for me as a substitute for SSI or the virtual() func.

Источник

How To Execute Shell Commands with PHP Exec and Examples?

Php provides web-based functionalities to develop web applications. But it also provides system related scripting and execution features. The exec() function is used to execute an external binary or program from a PHP script or application. In this tutorial, we will look at different use cases and examples of exec() function like return value, stderr, shell_exec, etc.

exec() Function Syntax

The PHP exec() syntax is like below where single parameter is mandatory and other parameters are optional.

• COMMAND is the command we want to execute with the exec() function. The command should be a string value or variable. COMMAND is a mandatory parameter.
• OUTPUT is the output of the COMMAND execution. OUTPUT is an array that can hold multiple values or lines. OUTPUT is optional where it can be omitted.
• RETURN_VARIABLE is the return value of the given COMMAND. RETURN _VALUE is generally the process status of the command. RETURN_VALUE is an integer and optional to use.

Run External System Binary or Application

We will start with a simple example. We will provide the command we want to run on the local operating system. In this example, we will create a directory named data . This directory will be created in the current working path. We can also specify the path explicitly like /var/data .

We can list the created directory with Linux file command like below. We will also provide the directory name because exec() function will only show the last line of the output. We will use echo to print the command output.

Print Output

We have already looked at printing output but I want to explain more about printing output. exec() function output or return can be printed with echo but the printed part will be only last line. So in a multi-line output, we can not see the output with echo . If we want to see the whole output we should use the system() function which will be explained below.

But we can use the output parameter like below. In this example, we will put command output to the o . The output parameter is in array type so we will use print_r to print output.

From the output we can see that the executed ls command output is stored in the variable named $o as an array. Every item is a files or folder which is located under the current working directory.

Assign Return Value into Variable

Using echo is not a reliable way to get the return value. We can use variables to set return values and use whatever we want. In this example, we will set the process return value to the variable named v.

Return Complete Output as String with shell_exec()

PHP language provides different functions as an alternative to exec() . We can use the shell_exec() function which will create a shell process and run given command. In this example, we will look at ls command and print output. With the shell_exec() function we can not get the return value of the shell process or command.

PHP shell_exec() Examples

In this part, we will make more examples about the PHP shell_exec() function. We will run the different system and Linux commands like date , whoami , ifconfig and mkdir .

Return Complete Output as String with system()

Another similar function is system() . system() function displays output directly without using echo or print . In this example, we will run the ls command again.

exec() Function vs shell_exec() Function

PHP also provides the shell_exec() function which is very similar to the exec() function. The main difference is shell_exec() function accepts a single parameter which is a command and returns the output as a string.

3 thoughts on “How To Execute Shell Commands with PHP Exec and Examples?”

Commands like ls work fine but creating a directory in not working for me not sure if I need to change any permissions or anything.
Any idea?

Almost certainly some kind of permissions problem. The user running the PHP script needs to have the ability to do what the command wants to do. Try creating a directory in /tmp and see if that works. Make sure your command is /bin/sh compatible since that’s hardcoded into PHP.

late but… write the command with path for success:
exec(“/usr/bin/mkdir dir”,$output,$return_val);

Источник