Terminfo Database


This content is not relevant to Windows.

If your application interacts with terminals (e.g. command line tools), your application may require the availability of a terminfo database so your application can properly interact with the terminal. The absence of a terminal database can result in the inability to properly colorize text, the backspace and arrow keys not working as expected, weird behavior on window resizing, etc. A terminfo database is also required to use curses or readline module functionality without issue.

UNIX like systems almost always provide a terminfo database which says which features and properties various terminals have. Essentially, the TERM environment variable defines the current terminal [emulator] in use and the terminfo database converts that value to various settings.

From Python, the ncurses library is responsible for consulting the terminfo database and determining how to interact with the terminal. This interaction with the ncurses library is typically performed from the _curses, _curses_panel, and _readline C extensions. These C extensions are wrapped by the user-facing curses and readline Python modules. And these Python modules can be used from various functionality in the Python standard library. For example, the readline module is used to power pdb.

PyOxidizer applications do not ship a terminfo database. Instead, applications rely on the terminfo database on the executing machine. (Of course, individual applications could ship a terminfo database if they want: the functionality just isn’t included in PyOxidizer by default.) The reason PyOxidizer doesn’t ship a terminfo database is that terminal configurations are very system and user specific: PyOxidizer wants to respect the configuration of the environment in which applications run. The best way to do this is to use the terminfo database on the executing machine instead of providing a static database that may not be properly configured for the run-time environment.

PyOxidizer applications have the choice of various modes for resolving the terminfo database location. This is facilitated mainly via the PythonInterpreterConfig.terminfo_resolution config setting.

By default, when Python is initialized PyOxidizer will try to identify the current operating system and choose an appropriate set of well-known paths for that operating system. If the operating system is well-known (such as a Debian-based Linux distribution), this set of paths is fixed. If the operating system is not well-known, PyOxidizer will look for terminfo databases at common paths and use whatever paths are present.

If all goes according to plan, the default behavior just works. On common operating systems, the cost to the default behavior is reading a single file from the filesystem (in order to resolve the operating system). The overhead should be negligible. For unknown operating systems, PyOxidizer may need to stat() ~10 paths looking for the terminfo database. This should also complete fairly quickly. If the overhead is a concern for you, it is recommended to build applications with a fixed path to the terminfo database.

Under the hood, when PyOxidizer resolves the terminfo database location, it communicates these paths to ncurses by setting the TERMINFO_DIRS environment variable. If the TERMINFO_DIRS environment variable is already set at application run-time, PyOxidizer will never overwrite it.

The ncurses library that PyOxidizer applications ship with is also configured to look for a terminfo database in the current user’s home directory (HOME environment variable) by default, specifically $HOME/.terminfo). Support for termcap databases is not enabled.


terminfo database behavior is intrinsically complicated because various operating systems do things differently. If you notice oddities in the interaction of PyOxidizer applications with terminals, there’s a good chance you found a deficiency in PyOxidizer’s terminal detection logic (which is located in the pyembed::osutils Rust module).

Please report terminal interaction issues at https://github.com/indygreg/PyOxidizer/issues.