shell_exec(3) [php man page]

SHELL_EXEC(3)								 1							     SHELL_EXEC(3)

shell_exec - Execute command via shell and return the complete output as a string

SYNOPSIS

       string shell_exec (string  $cmd)

DESCRIPTION

	This function is identical to the backtick operator.

PARAMETERS

	      o $cmd
		- The command that will be executed.

RETURN VALUES

	The output from the executed command or NULL if an error occurred or the command produces no output.

       Note

	       This  function  can return NULL both when an error occurs or the program produces no output. It is not possible to detect execution
	      failures using this function. exec(3) should be used when access to the program exit code is required.

EXAMPLES

       Example #1

	      A shell_exec(3) example

	      <?php
	      $output = shell_exec('ls -lart');
	      echo "<pre>$output</pre>";
	      ?>

NOTES

       Note

	       This function is disabled when PHP is running in safe mode.

SEE ALSO

       exec(3), escapeshellcmd(3).

PHP Documentation Group 													     SHELL_EXEC(3)

ESCAPESHELLCMD(3)							 1							 ESCAPESHELLCMD(3)

escapeshellcmd - Escape shell metacharacters

SYNOPSIS

       string escapeshellcmd (string  $command)

DESCRIPTION

       escapeshellcmd(3)  escapes  any	characters in a string that might be used to trick a shell command into executing arbitrary commands. This
       function should be used to make sure that any data coming from user input is escaped before this data is passed to the exec(3) or system(3)
       functions, or to the backtick operator.

	Following characters are preceded by a backslash: #&;`|*?~<>^()[]{}$, x0A and xFF.  ' and " are escaped only if they are not paired. In
       Windows, all these characters plus % are replaced by a space instead.

PARAMETERS

	      o $command
		- The command that will be escaped.

RETURN VALUES

	The escaped string.

EXAMPLES

       Example #1

	      escapeshellcmd(3) example

	      <?php
	      // We allow arbitrary number of arguments intentionally here.
	      $command = './configure '.$_POST['configure_options'];

	      $escaped_command = escapeshellcmd($command);

	      system($escaped_command);
	      ?>

       Warning

	      escapeshellcmd(3) should be used on the whole command string, and it still allows the attacker to pass  arbitrary  number  of  argu-
	      ments. For escaping a single argument escapeshellarg(3) should be used instead.

SEE ALSO

       escapeshellarg(3), exec(3), popen(3), system(3), backtick operator.

PHP Documentation Group 													 ESCAPESHELLCMD(3)