Command-not-found

This application implements the command-not-found spec at: https://wiki.ubuntu.com/CommandNotFoundMagic

If you want automatic prompts to install the package, set COMMAND_NOT_FOUND_INSTALL_PROMPT in your environment.

To use it in bash, please add the following line to your .bashrc file: . /etc/bash_command_not_found

To use it in zsh, please add the following line to your .zshrc file: . /etc/zsh_command_not_found Note that it overrides the preexec and precmd functions, in case you have defined your own.

Data sources

Command-not-found will for the following data sources:

1. sqlite3 DB in /usr/share/command-not-found/commands.db, if that is not found it will fallback to (2)
2. legacy /usr/share/command-not-found/programs.d/*.db gdbm style database

The datasource (1) is generated from data found on the archive server in deb822 format. The data is generated via https://code.launchpad.net/~mvo/command-not-found-extractor/+git/command-not-found-extractor and is downloaded via apt update.

The datasource (2) is generated via a static command-not-found-data deb package. It is less rich and dynamic than (1) and should be considered legacy and only be used if no better data source is available.

DB schemas

Legacy DB:

Simple key/value store with key program_name (e.g. bash) and value a comma separated list of packages that provide the program name. The filename indicates the component and architecuture via: $component-$arch.db.

Sqlite3 DB:

The database looks like this:

           CREATE TABLE IF NOT EXISTS "commands" 
           (
            [command] TEXT PRIMARY KEY NOT NULL,
            [pkgID] INTEGER NOT NULL,
            FOREIGN KEY ([pkgID]) REFERENCES "pkgs" ([pkgID])
           );
           CREATE TABLE IF NOT EXISTS "packages"
           (
            [pkgID] INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
            [name] TEXT,
            [version] TEXT,
            [priority] INTEGER
           );

There is no need to store the component because we do not display that in c-n-f. Note that the "name" in the "pkgs" table may include an architecture qualifier. This is an optimization for multi-arch systems, by default if there is "bash:amd64" and "bash:i386" on an amd64 multi-arch systems we will not store "bash:i386" in the DB at all and will store "bash:amd64" just as "bash". However for commands that are only available for the foreign arch (e.g. "wine:i386") the full qualified package name is stored in the DB and used in the c-n-f output.

Development

To run the tests type:

$ python -m unittest discover