[Bug 1957863] [NEW] coding errors in update-motd-fsck-at-reboot script

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You have been subscribed to a public bug by Matthieu Clemenceau (mclemenceau):

The script /usr/lib/update-notifier/update-motd-fsck-at-reboot contains some coding errors.
One of the errors hides the other error:

1. It sets two variables NEEDS_FSCK_CHECK and NEED_FSCK_CHECK (missing
'S') but only checks one of them (NEEDS_FSCK_CHECK).  Because of this
error, the script doesn't always initialize the value of
NEEDS_FSCK_CHECK at the start of the script, so whatever value might
happen to be passed in from the environment of the script could force a
check even if the script would not itself do so.

Rename variable NEED_FSCK_CHECK to NEEDS_FSCK_CHECK and always run your
Bourne shell scripts with the "-u" (check for undefined variables)
option enabled:  #!/bin/sh -u

2. It sets the variables with values "no" and "yes", but *any* value set in the variables means "yes".  (It doesn't check that the value is actually "yes", so even "no" means "yes".)  Because of coding error #1, this coding error #2 has no effect on the script operation, so if you fix coding error #1 without fixing this one, the script will incorrectly always run.  You have to fix both.
Change:

    if [ -n "$NEEDS_FSCK_CHECK" ]; then

to actually check for a "yes":

    if [ "$NEEDS_FSCK_CHECK" = 'yes' ]; then

P.S. This script uses dumpe2fs that waits for all the disks on your
system to spin up, which can significantly delay an ssh login to your
system, as well as cause unnecessary wear on all your normally idle
disks since the script seems to run frequently.  If you don't like this
behaviour (and don't need the fsck information it generates), you can
render the script inactive by adding this line to /etc/crontab:

    01 * * * * root f=/var/lib/update-notifier/fsck-at-reboot ; test -e
$f && touch $f

It would be nice if there were a cleaner way (perhaps something in
/etc/default/?) to disable all this disk-spin-up activity, but that
would be a different bug report.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: update-notifier-common 3.192.30.10
ProcVersionSignature: Ubuntu 5.11.0-46.51~20.04.1-generic 5.11.22
Uname: Linux 5.11.0-46-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: skip
Date: Thu Jan 13 23:40:37 2022
EcryptfsInUse: Yes
InstallationDate: Installed on 2020-10-07 (463 days ago)
InstallationMedia: Lubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
PackageArchitecture: all
SourcePackage: update-notifier
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.apt.apt.conf.d.10periodic: [modified]
mtime.conffile..etc.apt.apt.conf.d.10periodic: 2020-10-08T05:49:47.646282

** Affects: update-notifier (Ubuntu)
     Importance: Undecided
         Status: Confirmed


** Tags: amd64 apport-bug focal rls-jj-incoming third-party-packages
-- 
coding errors in update-motd-fsck-at-reboot script
https://bugs.launchpad.net/bugs/1957863
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