It appears the gnome-search-tool is not available in Bionic. On https://launchpad.net/ubuntu/bionic/amd64/gnome-search-tool/3.6.0-2 it says status Deleted.
I've downloaded the deb from Wily Proposed repo and installed that on Bionic and it works just fine.
So why has it been removed? And what are good alternatives, specially if you want a GUI to search for strings (or regex?) inside file content not just file names?
grep
all files for a strings (or regex) in a few minutes instead of 53 hours from the CLI see this Q&A: https://askubuntu.com/questions/1005437/greping-all-files-for-a-string-takes-a-long-time It's not what you are looking for because a GUI front end usingzenity
oryad
would need to be put into a bash script. – WinEunuuchs2Unix May 07 '18 at 10:55recoll
. It's in Bionic. – DK Bose May 07 '18 at 11:19