CommandNotFoundMagic
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| * '''Launchpad Entry''': https://launchpad.net/distros/ubuntu/+spec/foo * '''Created''': [[Date(2005-11-05T20:45:55Z)]] by MichaelVogt * '''Contributors''': MichaelVogt * '''Packages affected''': ##(see the SpecSpec for an explanation) * '''Launchpad Entry''': https://launchpad.net/distros/ubuntu/+spec/foo * '''Created''': [[Date(2005-11-04T23:14:14Z)]] by MichaelVogt |
* '''Launchpad Entry''': https://launchpad.net/distros/ubuntu/+spec/command-not-found-magic * '''Created''': <<Date(2005-11-04T23:14:14Z)>> by MichaelVogt |
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| == Rational == | == Rationale == |
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| Because ubuntu ships only with a single CD some commands that power-users expect are not installed (e.g. gcc, make). | Because Ubuntu ships only with a single CD some commands that power-users expect are not installed (e.g. gcc, make). |
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| dialog saying that installing the mentioned package is needed. | message saying that installing the mentioned package is needed. |
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| * from a "by-hand" file to include additonal stuff (like acroread) | * from a "by-hand" file to include additional stuff (like acroread) |
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| The command_not_found handler is in bash, no code for the python script has been written yet.. |
Code is available in http://ubuntu.suxx.pl/2006--1/bzr-archive/command-not-found--main/ and http://people.ubuntu.com/~mvo/bzr/command-not-found/mvo A initial implementation is available in edgy. A version that also displays the component that is required for the package and that fixes some filtering problem is available as 0.2.0 in edgy. == Problems == The real evil for this spec is the "update-alternatives" command. A common application like "vi" is not shipped by the various packages as "vi" but as "vim","nvi", etc and updated via update-alternatives to "vi" in the postinst scripts. This needs to be evaluated as well. The problem is that some packages embed the call in bash code with "update-alternative $pkg" (e.g. the emacs postinst), making it hard to automatically parse the code. == Comments == It could suggest another spelling to the command, using a simple Spell Corrector: http://www.peterbe.com/plog/spellcorrector http://www.norvig.com/spell-correct.html ---- CategorySpec |
Launchpad Entry: https://launchpad.net/distros/ubuntu/+spec/command-not-found-magic
Created: 2005-11-04 by MichaelVogt
Contributors: MichaelVogt, GustavoNiemeyer, DanielBurrows
Packages affected: bash
Summary
The "command not found" message is not very helpful. If e.g. the unzip command is not found but it's available in a package, it would be very interesting if the system could tell that the command is currently not available, but installing a package would provide it.
Rationale
Because Ubuntu ships only with a single CD some commands that power-users expect are not installed (e.g. gcc, make).
Use cases
John sees a tutorial of how to unzip a package using the unzip command, and tries to follow it. The needed package is not installed, so he gets a message saying that installing the mentioned package is needed.
Design
Bash has a "command_not_found" handler that is called in the interactive mode when a command is not found. The first argument is the command that is not found. We hook a custom python script into it that has a database (gdbm or similar) with the available commands as keys and some information (like a list of packages it is in) as value. This lookup needs to be fast. This information is assembled from various sources:
- from the Content-$arch file
- from a "by-hand" file to include additional stuff (like acroread)
a mirror with deb that are scanned for update-alternatives commands in
- postinst
Implementation
Code is available in http://ubuntu.suxx.pl/2006--1/bzr-archive/command-not-found--main/ and http://people.ubuntu.com/~mvo/bzr/command-not-found/mvo
A initial implementation is available in edgy. A version that also displays the component that is required for the package and that fixes some filtering problem is available as 0.2.0 in edgy.
Problems
The real evil for this spec is the "update-alternatives" command. A common application like "vi" is not shipped by the various packages as "vi" but as "vim","nvi", etc and updated via update-alternatives to "vi" in the postinst scripts. This needs to be evaluated as well. The problem is that some packages embed the call in bash code with "update-alternative $pkg" (e.g. the emacs postinst), making it hard to automatically parse the code.
Comments
It could suggest another spelling to the command, using a simple Spell Corrector: http://www.peterbe.com/plog/spellcorrector http://www.norvig.com/spell-correct.html
CommandNotFoundMagic (last edited 2008-08-06 16:20:46 by localhost)