R. Saravanan

Texas A&M University

sarava@mitotic.org

Derived from talks give at:

• Texas Linux Festival, San Antonio, August 4, 2012
• PyTexas, College Station, September 16, 2012

A GUI gives you sentences you can say to express yourself.

A command line interface gives you words.

Anonymous

• More powerful and flexible than the GUI

  • Not limited to actions that can be fitted on the screen
  • Pipe output of one command to another
    • i.e., form your own sentences using words!
  • Wild-carding, command completion, history recall

• Efficient use of screen real-estate

  • Easy to use on small screens and remotely (Mobile phones tend to use a menu-driven text UI, although not a CLI)

• Self-documenting

  • Useful for scripting and automation, especially on the server-side

• “Newbies” find a blank terminal screen confusing

  • Steep learning curve (need to learn basic commands first)
  • Abbreviated commands (efficient, but cryptic!)
  • Command have to be typed precisely (unlike natural language)
  • Poor feedback on the results of commands; difficult to undo
  • A GUI with good icons is more intuitive
    • Relies upon recognition rather than recall

• Looks dull and archaic (does not use rich monitor display)

  • Sometimes a picture is worth a thousand words

• Does not use the analog input capabilities of the mouse

• GNU Screen
• tmux
• Byobu

A Graphical Terminal Interface

• Aims to seamlessly blend the CLI and the GUI

• Fully backwards-compatible terminal emulator for xterm.

  • Use it just like a regular terminal interface, accessing additional graphical features only as needed

• Builds upon two earlier projects, XMLTerm and AjaxTerm

• Alpha quality (dogfood status for the past 7 weeks!)

• Project Page http://code.mindmeldr.com/graphterm

• Source code (BSD License) https://github.com/mitotic/graphterm

• Server: ~4500 lines of python

  • Tornado webserver, code from AjaxTerm
  • Websocket (2-way HTTP) connections between browser and server

• Client: ~2500 lines of HTML+JS+CSS

  • jQuery, AJAX editor (ACE)

• Adds a new xterm “escape” sequence to switch to a graphical screen mode to display HTML fragments (“pagelets”)

  • GraphTerm-aware programs can be written in any language: gls, gvi, …

• Browser connects to GraphTerm server using websockets

  • Host computers where the terminal session runs also connect to the same server (on a different port)

• Install
  • sudo easy_install graphterm
  • sudo gterm_setup
• Start server
  • gtermserver –auth_code=none
• Open terminal in browser (to connect to localhost)
  • http://localhost:8900
  • Terminal sessions have URLs of the form:
    • http://localhost:8900/<hostname>/tty1
    • http://localhost:8900/*/tty1 (wildcard)
  • First user owns the terminal session; others can watch/steal it
• Connect additional hosts to server
  • gtermhost --server_addr=domain <hostname>

• Backwards compatible with CLI, plus incremental feature set
• Clickable (hyperlinked) text for filenames and commands
  • Adaptive paste behavior (depending upon the current command line)
• Optional icons for file listings etc.
• Platform-independent client (HTML+Javascript)
  • Themable using CSS
• Pure python server (should work on any Unix-ish system)
• Touch-friendly
  • Translate clicks, taps, and drops into textual commands
• Cloud and collaboration-friendly
  • Single (tabbed) browser window to connect to multiple hosts
  • Drag and drop to copy files between different hosts
  • Screen sharing: A terminal session can be shared by multiple users

• A more fun (and powerful) replacement for the terminal
• A replacement for screen/tmux (detachable terminal)
• Manage a collection of computers using the browser
  • Wildcard remote access
  • Audit history of all commands
  • Debug Python programs using otrace
• For collaboration with other developers
  • Screen sharing and screen stealing
• For demonstrating or teaching CLI-based software
  • Create a virtual computer lab using the cloud
  • Receive live feedback from audience