Comment 6 for bug 601407

If I type this command first : "sudo DEBCONF_DEBUG='developer' sudo /etc/kernel/header_postinst"

or this command: DEBCONF_DEBUG='developer' sudo /etc/kernel/header_postinst.d/nvidia-common

I didn't receive any feedback.

But if I follow the procedure of Jean-Baptiste Lallement (with the "set -x" in the second line of /etc/kernel/header_postinst.d/nvidia-common),
the command "sudo DEBCONF_DEBUG='developer' sudo /etc/kernel/header_postinst"
works perfectly. Why? :)

The output:

+ . /usr/share/debconf/confmodule
++ '[' '!' '' ']'
++ PERL_DL_NONLAZY=1
++ export PERL_DL_NONLAZY
++ '[' '' ']'
++ exec /usr/share/debconf/frontend /etc/kernel/header_postinst.d/nvidia-common
+ . /usr/share/debconf/confmodule
++ '[' '!' 1 ']'
++ '[' -z '' ']'
++ exec
++ '[' '' ']'
++ exec
++ DEBCONF_REDIR=1
++ export DEBCONF_REDIR
+ db_set nvidia-common/obsolete-driver false
+ _db_cmd 'SET nvidia-common/obsolete-driver' false
+ IFS=' '
+ printf '%s\n' 'SET nvidia-common/obsolete-driver false'
+ IFS='
'
+ read -r _db_internal_line
+ RET='10 nvidia-common/obsolete-driver doesn'\''t exist'
+ case ${_db_internal_line%%[ ]*} in
+ return 10