Search document content in Mac & Linux

 If there's one feature I like most about Mac, it must be the spotlight search 'summoned' via the keyboard shortcut:  command-space.

It searches not only by filenames, but also the content text; not only in text files, but also in RTF, DOC, etc.  It makes folder boundaries disappear, and file names unimportant.  The files indexing is automatically done in background.

In Windows, about 10 years ago,  there was a Google desktop search sidebar tool, but discontinued.

In Linux, we have multiple built-in tools, eg.   updatedb, then locate pattern for file names;  or ascii content by  grep -HERin pattern path;  or  by more search criteria,   'find' command

Ubuntu has its all-in-one search works somewhat similarly.

For other distro's like mxlinux, an option maybe a tool: search monkey.   To install:

    sudo apt update

    sudo apt upgrade

    sudo apt install searchmonkey

For usage, 3 different ways:

(A) bottom-left menu, type search.  prefilled search location   $HOME

(B) terminal command line:

    $ searchmonkey

or 

    $ searchmonkey -d directory -f filename_regex -t text_regex

eg.

    searchmonkey -d /path/to/directory -f txt -t howto

(C) the handy way, configure in thunar preference  i.e. the explorer

file preference > customized action 

select   'find files here'

origin default is catfish

replace it with

        searchmonkey -d %f

then setup keyboard shortcut for this action.

Note that it's real time search, not from pre-processed database.  Therefore, searching in a big folder takes long time.