O Ubuntu também tem o bom e velho locate
da linha de comando.
locate reads one or more databases prepared by updatedb(8) and writes file names matching at least one of the PATTERNs to standard output, one per line.
updatedb
updatedb creates or updates a database used by locate(1). If the database already exists, its data is reused to avoid rereading directories that have not changed. updatedb is usually run daily by cron(8) to update the default database.
Exemplo ...
locate *.txt
resulta em
/boot/grub/gfxblacklist.txt
/discworld/.Trash-1000/files/Breaking Bad S04E10 Nl subs DutchReleaseTeam/DutchReleaseTeam NFO.txt
/discworld/.Trash-1000/files/Breaking Bad S04E10 Nl subs DutchReleaseTeam/Torrent downloaded from Demonoid.me.txt
/discworld/.Trash-1000/files/True Blood S04E12 HDTV.XviD (NL subs) DutchReleaseTeam/Dutch Release Team NFO Read Before Playing.txt
/discworld/.Trash-1000/files/True Blood S04E12 HDTV.XviD (NL subs) DutchReleaseTeam/Torrent_downloaded_from_Demonoid.me.txt
/etc/X11/rgb.txt
O que é mostrado é mostrado instantaneamente e você pode pesquisar com regex
.