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The CLI PHP script operates differently in its environment compared to its
web-server embedded counterpart. Shell scripts are running in their own pro-
cess, containing PHP and nothing else. Inside a web server, PHP shares the
process with the web server itself and any other modules the web server may
have loaded. The web server environment has many restrictions because of
this. For example, who gets standard input? What about signals, and what
happens if you fork (duplicate) the process? Usually all of these types of
resources are managed by the hosting web server. (more…)

On UNIX-like systems, PHP (with
back-ends other than CLI) looks for php.ini in /usr/local/lib by default. To be
more “shell-ish,” the CLI back-end looks for /etc/php-cli.ini by default, instead.
This makes it possible to keep separate php.ini files for your web server and
CLI/shell scripts, without having to specify the ­c option every time you run a
PHP-driven script. (more…)

The CLI version of PHP is quite similar to the CGI version, upon which it was
once based. The main difference lies in all the web server integration, which is
really what CGI is about. With CLI, PHP is trimmed down to the very basics,
and imports no GET or POST form variables, outputs no MIME headers in the
output, and generally does none of the behind-the-scenes that other SAPI
implementations do. (more…)

The CLI version of PHP is meant for writing standalone shell-scripts running
independently from any web server. As of PHP 4.3.0, the CLI version of PHP
is installed by default, alongside whatever web server interface you choose to
install. (more…)