Rawhide (rh(1)) lets you search for files on the command line using
expressions and user-defined functions in a mini-language inspired
by C. It's like find(1), but more fun to use.

Search criteria can be very readable and self-explanatory and/or
very concise and typeable, and you can create your own lexicon of
search terms. The output can include lots of detail, like ls(1).

You can search with file glob patterns and Perl-compatible regular
expressions (regexes). You can search by name, path, symlink target
path, body, access control list (ACL), extended attributes (EA),
and all the usual file metadata (file type, permissions, owner,
size, modification time, etc.).

rmw (ReMove to Waste) is a safe-remove utility for the command line.
Its goal is to conform to the FreeDesktop.org Trash specification
and therefore be compatible with KDE, GNOME, XFCE, and others.
Desktop integration is optional however, and by default, rmw will
only use a waste folder separated from your desktop trash. One of
its unique features is the ability to purge files from your
Waste/Trash directories after x number of days.

Ugrep supports an interactive query UI and can search file systems, source
code, text, binary files, archives, compressed files, documents and use
fuzzy search.

The ugrep-indexer utility recursively indexes files to accelerate recursive
searching on file systems with ugrep.