PHP RFC - Deprecate backtick operator


The backtick operator (`dir D:\foo`) is used to execute commands via shell.

The same functionality is also available as shell_exec().


This RFC proposes to deprecate (by triggering one among E_DEPRECATED, E_STRICT or E_NOTICE) it in PHP 7.3 and suggest to use shell_exec() instead:

  • in case PHP decided in future to use backtick enclosed strings for Unicode strings
  • because it is a shady way to execute a rare and dangerous operation
  • because it is weirdly specific to a rare operation; regexp literals, xml-strings literals are way more common use cases, but they don't have a specific string literal

Backward Incompatible Changes

None, the feature will continue to work until it is removed in future PHP versions, but a notice will be emitted.

Proposed PHP Version:



2/3 majority will be required.


rfc/deprecate-backtick-operator.txt · Last modified: 2018/02/11 20:59 by wesnetmo