Commands execution from php, idea(s) how to restrict from code consumer's scope

Description

The original discussion stemmed from there.
Basically how to, more effectively, restrict php process user access to system commands. Albeit the implementation idea had been rejected, for valid reasons, it should not stop to improve in this area. Note that calls like execvP allows to enforce specific search paths but is even less standard than execvpe.

从链接的 externals.io 讨论以及 issue 中对 execvP 和 execvpe 的引用开始。将限制 PHP 进程访问系统命令这一既定目标与这些 API 的限制进行比较，然后记录一个具体且有技术依据的方向及其范围。