TUIs, a Smoke-Jumping Admin’s Best Friend

TUI Tools

Even today you can find many examples of TUI applications. They are very fast – faster than GUIs – and easy to use. They help CLI applications that have a large number of options and often provide visual feedback. Many of these tools are widely used, including on HPC systems, to collect statistics across the cluster and manage nodes; they are ideally suited for debugging and testing a small number of nodes.

TUIs are still popular for general applications, although perhaps not so much as administration tools. Nonetheless, they are still used and new ones are still being developed. Table 1 lists a number of administrative and non-administrative TUIs.

Table 1: Example TUIs

Writing TUIs

Rather than just present a list of TUI applications that can be used for administration or as everyday applications, I will illustrate that it is fairly straightforward to write these applications, particularly for administration tasks.

A few main libraries or toolkits have been helpful; the first, and probably largest, is curses. Originally written in the late 1970s, curses was optimized and expanded in the early 1980s for the video game Rogue. It then began to be used for a number of applications. Development of curses slowed down, and a new library, ncurses, was developed that proved to be more popular than curses. As part of the GNU Project, it is still being developed, although at a slower pace. Figure 1 shows a sample ncurses screenshot.

Figure 1: ncurses-based menuconfig (Wikipedia, CC BY-SA 3.0).

Another option is the Newt library, which focuses on color TUIs (Figure 2) and uses a widget approach, making programming a TUI much easier. With Newt, you can create stacked windows, entry widgets, checkboxes, radio buttons, labels, plain text fields, scrollbars, and so on. In Python, this library is referred to as snack  and was originally developed for Red Hat’s TUI installer, Anaconda.

Figure 2: The Partimage tool uses Newt to create its user interface (Wikipedia, GPL).

A number of tutorials on the web can guide you in using Newt with pretty much any language you want. (Sorry, Fortran-ers, I don’t see anything for us yet.) Python is a fairly common language for using Newt (python- snack ), and a Jupyter notebook can help you learn Newt in Python.

Another useful TUI library that can be used with Python and Bash is called dialog , which you can use to create pop-up dialog boxes from Bash scripts (Figure 3). Furthermore, dialog  has been rolled into a Python library named, aptly enough, pythondialog  that allows you to use dialog boxes and other constructs from the dialog  library in your Python code.

Figure 3: Sample pop-up dialog from Bash script: dialog --title "Message" --msgbox 'Your job is done' 6 20

If you are interested in writing TUIs for system administration, a great place to start is with the psutil  library, which is great for gathering system statistics. Then, you can take a look at the scripts  subdirectory on GitHub, where you can find a number of sample scripts for creating a TUI (e.g., the top  clone top.py ). You can also look at other TUIs to understand how to create plots, strip charts, and other useful features. Don’t forget, these interfaces are all text based and can be easily used over port 22 (SSH).

Be sure to examine the admin tools mentioned in Table 1. The charting capability, even with just text-based graphics, is great. I love using these tools to get a simple view of how a node is behaving. Take a look at the code and even think about a way to make a function for creating these plots (please create Python interfaces to make life easier).