Widgets, sockets, and interactivity

A widget appears as an overlay on the terminal (like picture-in-picture for TVs, or dashboard widgets on the Mac). This is an experimental feature which allows programs running in the background to display information overlaid on the terminal. (It may be disabled using the --widget-port=0 option.) The widget is accessed by redirecting stdout to a Bash tcp socket device whose address is stored in the environment variable GTERM_SOCKET. For example, the following command will run a background job to open a new terminal in an overlay iframe:

gframe -f --opacity=0.2 http://localhost:8900/local/new > $GTERM_SOCKET &

You can use the overlay terminal just like a regular terminal, including having recursive overlays within the overlay! To delete the widget, just close the socket connection by killing the background job. (You can use the fg command to bring the job to the foreground and then kill it.)

A simple example of a live feed widget is to combine gfeed with tail -f:

tail -f output.log | gfeed > $GTERM_SOCKET &

The above feed will display the new lines appended to the file output.log.

Another example of widget use is to display live audience feedback on the screen during a presentation, sort of like a “twitter feed”. The widget background job should be started before using greveal to make a presentation:

gchat 2> $GTERM_SOCKET 0<&2 | gfeed > $GTERM_SOCKET &
greveal $GTERM_DIR/bin/landslide/graphterm-talk1.md | gframe -f

The first command uses gchat to capture feedback from others viewing the terminal session as a stream of lines from $GTERM_SOCKET. The viewers use the overlaid chat button to provide feedback. The stdout from gchat is piped to gfeed which displays its stdin stream as a “live feed” overlay, also via $GTERM_SOCKET.

To display a live twitter feed as an overlay on a presentation, you can use the commands:

gtweet -w -f -s topic > $GTERM_SOCKET &
greveal $GTERM_DIR/bin/landslide/graphterm-talk1.md | gframe -f