(PHP 4, PHP 5, PHP 7)
system — Execute an external program and display the output
system() is just like the C version of the
function in that it executes the given
command and outputs the result.
The system() call also tries to automatically flush the web server's output buffer after each line of output if PHP is running as a server module.
If you need to execute a command and have all the data from the command passed directly back without any interference, use the passthru() function.
The command that will be executed.
return_var argument is present, then the
return status of the executed command will be written to this
Returns the last line of the command output on success, and
Example #1 system() example
// Outputs all the result of shellcommand "ls", and returns
// the last output line into $last_line. Stores the return value
// of the shell command in $retval.
$last_line = system('ls', $retval);
// Printing additional info
<hr />Last line of the output: ' . $last_line . '
<hr />Return value: ' . $retval;
If a program is started with this function, in order for it to continue running in the background, the output of the program must be redirected to a file or another output stream. Failing to do so will cause PHP to hang until the execution of the program ends.