你不需要bash来将内容附加到文件中，你可以使用fopen和a标志，或者file_put_content和FILE_APPEND标志：

$nome = $_POST['nome'] ?? throw new Exception('nome not defined');
$ramal = $_POST['ramal'] ?? throw new Exception('ramal not defined');
$passwd = $_POST['passwd'] ?? throw new Exception('passwd not defined');

$newContent = <<< BASH

[$nome]
type=friend
username=$nome
callerid=$nome
mailbox =$ramal
secret=$passwd
host=dynamic
context=local-tmp

BASH;

$newExtensionsContent = PHP_EOL . "exten => $ramal,1,Dial(SIP/$ramal,10,t)";

file_put_contents('sip.conf', $newContent, FILE_APPEND);
file_put_contents('extensions.conf', $newExtensionsContent, FILE_APPEND);