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

Bug #335231 reported by Alexander Jones on 2009-02-27
Affects Status Importance Assigned to Milestone
command-not-found (Ubuntu)

Bug Description

Binary package hint: command-not-found

WHenever I goof a command like

alex@fizz:~$ pytohn

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
 PATH=(custom, user)
SourcePackage: command-not-found
Uname: Linux 2.6.28-6-generic x86_64

Alexander Jones (alex-weej) wrote :
Øyvind Jensen (jegerjensen) wrote :

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.

Michael Vogt (mvo) on 2009-06-26
Changed in command-not-found (Ubuntu):
importance: Undecided → Wishlist
status: New → Confirmed
Zygmunt Krynicki (zyga) wrote :

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) wrote :

@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) wrote :

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.

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