What's the fastest way to locate a WORD in a file via the command line?

cat path/to/your/file.txt | grep the_word_you_want_to_find

This technique comes in handy when you're trying to locate a certain configuration directive within a configuration file (as illustrated in the following example):

cat /etc/php5/apache2/php.ini | grep upload_max_filesize
upload_max_filesize = 2M