command-not-found should print something on the console immediately

[Alexander Jones]

Binary package hint: command-not-found

WHenever I goof a command like

alex@fizz:~$ pytohn blabla.py

if the command-not-found cache is cold, it may take a couple of seconds to return and finally print

bash: pytohn: command not found

During this time, I don't know whether the command is actually running or not.

Therefore, I suggest c-n-f prints something immediately like "pytohn not found. searching bla bla". At least then I can see straight away when I have goofed and have a chance to Ctrl+C it.

ProblemType: Bug
Architecture: amd64
DistroRelease: Ubuntu 9.04
NonfreeKernelModules: nvidia
Package: command-not-found 0.2.31ubuntu2
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: command-not-found
Uname: Linux 2.6.28-6-generic x86_64

[Øyvind Jensen (jegerjensen)]

I support this proposal. The few seconds it takes feels like a very long time, so an immediate feedback would give the end user a smoother experience.

[Zygmunt Krynicki (zyga)]

I think it's fairly easy to implement. We could set up a timer that goes of after 0.5 seconds from python startup and print something like "Searching... please wait". I'd love to implement this.

BTW: Does anyone know how to simulate "cold" storage reliably? I'd like to fine-tune the timer delay using some non-guessed value.

[Michael Vogt (mvo)]

@Zygmunt: You can run:
echo 3 > /proc/sys/vm/drop_caches

to get a cold disk cache again. On my (relatively new) system the time after that is:
$ time /usr/lib/command-not-found foobar
real 0m1.851s
user 0m0.208s
sys 0m0.144s

[Zygmunt Krynicki (zyga)]

Thanks Michael, this will be very handy!

I'm testing a dbus-based service that is starting on demand and exits after 60 seconds of inactivity. This makes it possible to get rid of "cold cache" issue. As a second step the now-trivial client can be rewritten in vala and linked statically to get fastest possible startup.