If you wrap string in the proper tags you will get the same result, but with different offset (28 chars):
tee "index.html" <<eol ; echo -e "\n"; kmimetypefinder5 index.html <!DOCTYPE html> <html><body>`printf "x"%.0s {1..228}` use strict </body></html> eol # -> text/html -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to shared-mime-info in Ubuntu. https://bugs.launchpad.net/bugs/1890716 Title: misidentifies .html file as Perl script when it contains JavaScript "use strict" Status in shared-mime-info: Unknown Status in kde-cli-tools package in Ubuntu: New Status in shared-mime-info package in Ubuntu: Fix Committed Status in shared-mime-info package in Debian: Confirmed Bug description: For .html files `xdg-mime` reports wrong type. The culprit is the `"use strict"` phrase which is used in JavaScript. It should not mistake .html files for anything else except of text/html ! STEPS TO REPRODUCE: Run the following step by step in any folder: 1. $ echo "\"use strict\"" > index.html 2. $ xdg-mime query filetype index.html # -> application/x-perl - this should be text/html! Platform: Ubuntu 20.04.1 LTS (Focal Fossa)" Linux version 5.4.0-42-generic (buildd@lgw01-amd64-038) (gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)) xdg-utils: 1.1.3-2ubuntu1 To manage notifications about this bug go to: https://bugs.launchpad.net/shared-mime-info/+bug/1890716/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp