The search string is a highly specific example of a Google Dork (or Google Hacking) query. At first glance, it looks like a random string of command-line jargon. However, to a trained analyst, it reads as a precise instruction to locate exposed Facebook login credentials.
: A specific keyword used to target files intended to store or log passwords. allintext username filetype log passwordlog facebook full
For an interesting dive into why this specific search exists and the risks it highlights, the following articles provide excellent context: The search string is a highly specific example