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Using GraphTerm

Introduction

(See the README file for information on installing GraphTerm.)

To start the GraphTerm server, use the command:

gtermserver --auth_code=none

Type gtermserver -h to view all options. You can use the --daemon=start option to run it in the background.

Once the server is running, you can open a terminal window on the localhost in the following ways:

  • Specify the --terminal option when starting gtermserver
  • Use the gterm command in any terminal
  • Within a GraphTerm window, you can use the New menu option, or use the keyboard shortcut Ctrl-Alt-T to create a new GraphTerm window

To open a remote terminal window, open up a browser of your choice that supports websockets, such as Google Chrome, Firefox, or Safari (Chrome works best), and enter the following URL:

http://localhost:8900

Once within the graphterm browser page, select the host you wish to connect to and create a new terminal session on the host.

Once you have a terminal, try out the following commands:

gls <directory>
gvi <text-filename>

These are graphterm-aware scripts that imitate basic features of the standard ls and vi commands. To display images as thumbnails, use the gls -i ... command. Use the -h option to display help information for these commands, and read the UsingGraphicalFeatures tutorial for usage examples.

You can use the command which gls to determine the directory containing graphterm-aware commands, to browse for other commands, which include:

giframe [-f] [filename|URL] To view files/URLs (or HTML from stdin) in inline iframe

gimage [-f] [filenames] To view images inline, or as a fullpage slideshow (with -f option)

glandslide A GraphTerm-aware version of Landslide, a web-based slideshow program

gtutor [...] example.py A command-line version of the Online Python Tutorial at pythontutor.com

gmatplot.py An inline matplotlib plotting demo

gsnowflake.py An inline plotting demo for the SVG module svgwrite

yweather [location] To view weather forecasts

gtweet [-s keywords]|tweet To send, search, or receive tweets

(There is also a sample gcowsay command which can be downloaded separately from its Github repository)

Visual cues

In the default theme, blue color denotes text that can be clicked or tapped. The action triggered by clicking depends upon two factors, whether there is text in the current command line, and whether the Control modifier in the Bottom menu is active. Click on the last displayed prompt to toggle display of the Bottom menu. Clicking on other prompts toggles display of the command output (unless the Control modifier is used, in which case the entire command line is copied and pasted.)

Navigating folders/opening files

You can navigate folders in GraphTerm just like you would do in a GUI, while retaining the ability to drop back to the CLI at any time. If the current command line is empty, clicking on a folder or filename displayed by the gls command will change the current directory to the folder, or cause the file to be opened. If you have typed anything at all in the current command line, even if it is just a space, the clicking action will cause text to be pasted into the command line, without any command being executed. You can edit the pasted text, then press the Enter key to execute it.

Icon display

Select icons in the top menu to activate icon display for commands like gls.

Themes

Themes, selected using the top menu, are a work in progress, especially the 3-D perspective theme (which only works on Chrome/Safari).

Copy/paste

For certain browsers (e.g., desktop Chrome/Safari), the usual Command-V or Control-V key sequence should directly paste text from the clipboard. If that doesn't work, there are a couple of other ways to paste text. First, you can use the keyboard shortcut Control-T to open a popup window, paste the text into the popup window using the browser's paste menu command or a keyboard shortcut, such as Command/Control-V, and then type Control-T again to insert the text at the GraphTerm cursor location. (The popup paste window can also be accessed from the Actions menu.) Alternatively, for some browsers, and on the iPad, you can click on the cursor before beginning the paste operation and then paste the text directly. This second technique may not always work well for text copied from non-plain text sources, such as a web page.

Drag and drop

Sort of works! You can drag a filename (grabbing the icon does not work) and drop it on a folder, an executable, or the command line. For drag-and-drop between two GraphTerm windows running on the same host, the file will be moved to the destination folder. For windows on two different hosts, the file will be copied. (Graphical feedback for this operation is not properly implemented at this time. Look at the command line for the feedback.)

Command recall

If the command line is empty, up/down arrows will use the underlying shell for command recall (like Control-P and Control-N). If the command line contains any text, including whitespace, up/down arrows will cause GraphTerm to search for matching previous commands that begin with the text already typed (ignoring any leading whitespace). You can use the right arrow to complete the recalled command (for editing) or use the Enter key to execute it. Typing any other key, including the left arrow, will cancel the command recall process.

iPad usage

Click on the cursor to display virtual keyboard on the iPad. The Bottom menu, exposed by clicking on the lowermost prompt, can be quite useful on the iPad.

Choosing the terminal type

The default terminal type is set to xterm, but it may not always work properly. You can also try out the terminal types screen or linux, which may work better for some purposes. You can use the --term_type option when running the server to set the default terminal type, or use the export TERM=screen command. (Fully supporting these terminal types is a work in progress.)

Multiple hosts

More than one host can connect to the GraphTerm server. The local host is connected by default (but this can be disabled using the --nolocal option). To connect an additional host, run the following command on the computer you wish to connect:

gtermhost --server_addr=<serveraddr> <hostname>

where serveraddr is the address or name of the computer where the GraphTerm server is running (which defaults to localhost). You can use the --daemon=start option to run the gtermhost command in the background. By default, the Graphterm server listens for host connections on port 8899. The multiple host feature should only be used within a secure network, not on the public internet.

NOTE: Unlike the sshd server, the gtermhost command is designed to be run by a normal user, not a privileged user. So different users can connect to the GraphTerm server pretending to be different "hosts" on the same computer. (If you are running a Python server, it can connect directly to the GraphTerm server as a "host", allowing it to be dynamically introspected and debugged using otrace.)

Sessions and "screensharing"

For each host, sessions are assigned default names like tty1 etc. You can also create unique session names simply by using it in an URL, e.g.:

http://localhost:8900/local/mysession

Anyone with access to the GraphTerm server can use the session URL to connect to it. This is like "screensharing", but more efficient, because only the content is shared, not the graphical themes. The first user to create a session "owns" it, until they detach from it. Others connecting to the same session have read-only access, unless they "steal" the session (see the Action menu). For example, if you forgot to detach your session at work, you can ssh to your desktop from home, use SSH port forwarding (see below) to securely access your work desktop, and then steal the session using your home browser.

NOTE: Although GraphTerm supports multiple users, it currently assumes a cooperative environment, where everyone trusts everyone else. (This may change in the future.)

Wildcard sessions and multiplexing

A session path is of the form session_host/session_name. You can use the shell wildcard patterns *, ?, [] in the session path. For example, you can open a wildcard session for multiple hosts using the URL:

http://localhost:8900/*/tty1

For normal shell terminals, a wildcard session will open a "blank" window, but any input you type in it will be broadcast to all sessions matching the pattern. (To receive visual feedback, you will need to view one or more of the matching sessions at the same time.)

For otrace debugging sessions of the form */osh, GraphTerm will multiplex the input and output in wildcard terminals. Your input will be echoed and broadcast, and output from each of the matching sessions will be displayed, preceded by an identifying header (with the special string ditto used to indicate repeated output). See the otrace integration section for more information.

NOTE: Multiplexed input/output display cannot be easily implemented for regular shell terminals.

Webcasting

If you enable the Webcast in the top menu, anyone can use the session URL to view the session, without the need for authentication, but will not be able to steal it. Use this feature with caution to avoid exposing exposing sensitive data.

Slideshows

The glandslide command, which is a slightly modified version of the web-based slide slideshow program Landslide, can be used to create a slideshow from Markdown (.md) or reStructured Text (.rst) files. A few sample .md files are provided in the graphterm/bin/landslide directory of the distribution. To view a slideshow about GraphTerm, type:

glandslide -o graphterm-talk1.md | giframe -f

Type h for help and q to quit the slideshow. (The unmodified Landslide program can also be used, with the -i option, but remote sharing will not work.)

The gimage command, which displays images inline, can also be used for slideshows and simple presentations. Just cd to a directory that has the images for a slideshow, and type:

gimage -f

To select a subset of images in the directory, you can use a wildcard pattern. For publicly webcasting a slideshow, use the -b option.

Command-line version of pythontutor.com

The command gtutor implements a command-line version of the Online Python Tutorial from pythontutor.com. It produces HTML output that can be piped to giframe for inline display. To trace the execution of a sample program example.py, use it as follows:

gtutor example.py | giframe -f

More sample programs may be found in the directory $GRAPHTERM_DIR/bin/pytutor/example-code. Of course, you can use gtutor to trace any other (small) python program as well. Type gtutor -h to display the command line options. Note: By default, gtutor accesses the browser CSS/JS files from pythontutor.com. To use gtutor in an offline-mode, you will need to specify the --offline option and also download the Online Python Tutorial code from GitHub and copy/rename the main source directory (currently v3) as $GRAPHTERM_DIR/www/pytutor so that GraphTerm can serve the CSS/JS files locally.

Advanced usage: You can embed tutorials within a Landslide/Markdown presentation by including an iframe HTML element in the presentation file, with the src attribute set to a graphterm URL, such as http://localhost:8900/local/tutorial. This will open up a graphterm window where you can either run gtutor interactively or use giframe -f to display an HTML file created previously using gtutor.

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 that allows programs running in the background to display information overlaid on the terminal. The widget is accessed by redirecting stdout to a Bash tcp socket device whose address is stored in the environment variable GRAPHTERM_SOCKET. For example, the following command will run a background job to open a new terminal in an overlay iframe:

giframe -f --opacity=0.2 http://localhost:8900/local/new > $GRAPHTERM_SOCKET &

You can use the overlay terminal just like a regular terminal, including having recursive overlays within the overlay!

A specific example of widget use is to display live feedback on the screen during a presentation. You can try it out in a directory that contains your presentation slides as images:

gfeedback 2> $GRAPHTERM_SOCKET 0<&2 | gfeed > $GRAPHTERM_SOCKET &
gimage -f

The first command uses gfeedback to capture feedback from others viewing the terminal session as a stream of lines from $GRAPHTERM_SOCKET. The viewers use the overlaid feedback button to provide feedback. The stdout from gfeedback is piped to gfeed which displays its stdin stream as a "live feed" overlay, also via $GRAPHTERM_SOCKET. (The gimage -f command displays all the images in the directory as a slideshow.)

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

gtweet -f -s topic > $GRAPHTERM_SOCKET &
gimage -f

Security

The GraphTerm is not yet ready to be executed with root privileges. Run it logged in as a regular user. The --auth_code option can be used to specify an authentication code required for users connecting to the server. Although multiple hosts can connect to the terminal server, initially, it would be best to use graphterm to just connect to localhost, on a computer with only trusted users. You can always use SSH port forwarding (see below) to securely connect to the GraphTerm server for remote access. As the code matures, security will be improved through the use of SSL certificates and server/client authentication. (SSL/https support is already built in. Feel free to experiment with it, although it is not yet ready for everyday use.)

SSH and port forwarding

If you login to a remote computer using SSH, you can use the Action -> Export Environment menu option to set the Bash shell environment variables on the remote computer. This will allow some, but not all, of GraphTerm's features to work on the remote session. If you wish to use more features, set the PATH environment variable on the remote machine to allow access to gls and other commands, and also use reverse port forwarding to forward your local port(s) to the remote computer, e.g.:

ssh -R 8898:localhost:8898 user@remote-computer

Currently, the most secure way to access the GraphTerm server running on a remote computer is to use SSH port forwarding. For example, if you are connecting to your work computer from home, and wish to connect to the GraphTerm server running as localhost on your work computer, use the command:

ssh -L 8900:localhost:8900 user@work-computer

This will allow you to connect to http://localhost:8900 on the browser on your home computer to access GraphTerm running on your work computer.

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