Why a long delay after command not found?

Often when I mistype a command such as ls (e.g. I hit ENTER before I type ‘s’) there is a long (~2s) delay after the terminal displays:

bash: l: command not found...

I can understand the reasons for a similar delay after an incorrect password is entered, per Why is there a big delay after entering a wrong password?. But why delay after an unrecognized command? Does FAIL_DELAY in /etc/login.defs affect this also?

Answers:

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Method 1

after some research I have found this:

• try to uninstall the command-not-found package with $>yum remove command-not-found then install it again with >$yum install command-not-found (just in case you have that package installed on your system).

if that doesn’t help try:

• add this to your ~/.bashrc file:

  unset command_not_found_handle

Method 2

I found that the best solution, at least on Fedora, is to modify the configuration file
/etc/PackageKit/CommandNotFound.conf

as the biggest delay comes from the search for packages to install, if you modify
SoftwareSourceSearch=true in SoftwareSourceSearch=false

the delay is almost 0 and you still get warned about misspellings, which can be useful.

Method 3

Fedora uses something similar.

If you want to just remove this feature use:

yum remove PackageKit-command-not-found

Method 4

In my case it’s because of some known proxy bug in /usr/libexec/pk-command-not-found

Failed to search for file: cannot update repo 'updates':
Cannot prepare internal mirrorlist:
Curl error (28): Timeout was reached for https://mirrors.fedoraproject.org/metalink?repo=updates-released-f28&arch=x86_64 
[Connection timed out after 30002 milliseconds]

My proxy configuration is correct because downloading the exact same URL with a bare curl command succeeds instantly.

I checked the pk-command-not-found process does have the proxy configuration:

tr  '' 'n' < /proc/$(pgrep -f pk-command-not-found)/environ | grep -i proxy

However it does not use it for some unknown reason.

https://bugzilla.redhat.com/show_bug.cgi?id=1553368

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0