which is a Unix command used to identify the location of executables. The command takes one or more arguments; for each of these arguments, it prints the full path of the executable to stdout that would have been executed if this argument had been entered into the shell.
which helps to locate a command, it prints the absolute command path as below:
which php /usr/bin/php
Below we will provide with a list of the most common server script/binary locations:
PHP
/usr/bin/php
MySQL
/usr/bin/mysql
CURL
/usr/bin/curl
WGET
/usr/bin/wget
Bash Script
/usr/bin/bash
PERL
/usr/bin/perl
PYTHON
/usr/bin/python