Why environment variables don’t suppress WP-CLI PHP Deprecated warnings — the phar + shebang path and a three-part structural fix

A previous post covered how to absorb PHP 8.2 Deprecated warnings from WP-CLI using a three-layer defense. The approach — prepending WP_CLI_PHP_ARGS to set error_reporting — works in many environments. But a case came up where Deprecated warnings wouldn’t disappear despite the same configuration. Tracing the cause revealed a structural reason why the environment variable never arrived. This post records that root cause and the three-part fix added in v1.6.8.

Why environment variables don’t arrive — the phar + shebang execution path

An agency reported that on Xserver, plugin list retrieval was failing across multiple sites (referred to here as "site A / site B") with a large volume of Deprecated messages. We reproduced the same behavior on our own Xserver setup (PHP 8.2.30, WP-CLI 2.7.1) and traced the execution path.

Xserver’s /usr/bin/wp is a phar binary. Inside, it starts with a #!/usr/bin/env php shebang, so the actual startup sequence looks like this:

shell → /usr/bin/wp (shebang: #!/usr/bin/env php)