There's nothing built in, exactly, but there are two ways to get at the scrollback text.
You can configure the
XTerm.vt100.on5Clicks resources (or from
on1Clicks onwards, for that matter) to choose to copy the whole scrollback to the X11 PRIMARY selection. For example, to copy the whole scrollback on a quadruple click, put this line in your
You'll then have to arrange your own method for bringing up some way to search the content of the X selection, such as opening an editor or a pager with a window manager binding.
You can call the
print-everything action to send the whole scrollback to a program determined by the
XTerm.vt100.printerCommand resource. For example, to open the scrollback in less (running in a new xterm) when you press Ctrl+/, put these lines in your
XTerm.vt100.printerCommand: xterm -e sh -c 'less <&3' 3<&0
XTerm.vt100.translations: #override Ctrl ~Meta ~Shift <Key>slash: print-everything()