where can I find the php.ini for php-cli

Better yet: $ php --ini

This will also show all extra *.ini files loaded (usually hanging around in some conf.d dir in debian):

Configuration File (php.ini) Path: /etc/php5/cli
Loaded Configuration File: /etc/php5/cli/php.ini
Scan for additional .ini files in: /etc/php5/cli/conf.d
Additional .ini files parsed: /etc/php5/cli/conf.d/apc.ini,
/etc/php5/cli/conf.d/curl.ini,
/etc/php5/cli/conf.d/gd.ini,
/etc/php5/cli/conf.d/geoip.ini,
/etc/php5/cli/conf.d/imagick.ini,
/etc/php5/cli/conf.d/imap.ini,
/etc/php5/cli/conf.d/ldap.ini,
/etc/php5/cli/conf.d/memcache.ini,
/etc/php5/cli/conf.d/memcached.ini,
/etc/php5/cli/conf.d/ming.ini,
/etc/php5/cli/conf.d/mysql.ini,
/etc/php5/cli/conf.d/mysqli.ini,
/etc/php5/cli/conf.d/pdo.ini,
/etc/php5/cli/conf.d/pdo_mysql.ini,
/etc/php5/cli/conf.d/pdo_sqlite.ini,
/etc/php5/cli/conf.d/snmp.ini,
/etc/php5/cli/conf.d/sqlite.ini,
/etc/php5/cli/conf.d/sqlite3.ini,
/etc/php5/cli/conf.d/suhosin.ini,
/etc/php5/cli/conf.d/tidy.ini,
/etc/php5/cli/conf.d/xdebug.ini,
/etc/php5/cli/conf.d/xsl.ini

Note that this was about php-cli, php-cgi does not have this afaik.

At my last job, I got in the habit of specifying my ini file on every execution...

C:\php\cli\php.exe -c C:\php\php.ini myscript.php

You can find php.ini using the below command. in LINUX

find / -name php.ini

or

locate php.ini

Just ask PHP:

php -i |grep php\.ini