[Bug 1883441] [NEW] Fatal interaction between sfdisk and lsblk

[Kevin O'Gorman]

Public bug reported:

I'm posting this against util-linux because it's lsblk calls that fail,
but the failure depends on a prior call to sfdisk which is part of the
fdisk package.  Remove the sfdisk call, and the failure does not happen,
at least in my test setup.

A call to sfdisk in a script causes a failure of a later series of calls
to lsblk, in which lsblk fails to return information.

I know sfdisk is designed for humans, but I'm wanting to automate the
operation of its --backup option, and don't know of another way.  In any
event, this failure shoudl be addressed.

I'm attaching a script with illustrates both the problem and a
workaround.  The workaround is to introduce a "sleep 1" call in between
the calls to lsblk.  I can't even imagine why this works, but it does in
my configuration.  I call the script with the name of a device which
contains two ntfs partitions, and the name of a directory where results
are to be stored.  The directory must contain a "clone.log" file (it can
be empty; it's just to make sure I'm naming the correct directory).

If I call it so it fails:
   bash b5.sh sda /tmp
because the final lsblk call does not return any information

However, if I call is to, it succeeds:
   bash -s b5.sh sda /tmp
because the "-s" switch introduces a "sleep 1" call between lsblk calls.

This makes no sense, which is why I consider it a bug.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: util-linux 2.31.1-0.4ubuntu3.6
ProcVersionSignature: Ubuntu 4.15.0-101.102-generic 4.15.18
Uname: Linux 4.15.0-101-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.9-0ubuntu7.15
Architecture: amd64
Date: Sun Jun 14 09:36:17 2020
SourcePackage: util-linux
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: util-linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug bionic

** Attachment added: "shell script which illustrates the bug and a workaround"
   https://bugs.launchpad.net/bugs/1883441/+attachment/5383785/+files/b5.sh

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to util-linux in Ubuntu.
https://bugs.launchpad.net/bugs/1883441

Title:
  Fatal interaction between sfdisk and lsblk

Status in util-linux package in Ubuntu:
  New

Bug description:
  I'm posting this against util-linux because it's lsblk calls that
  fail, but the failure depends on a prior call to sfdisk which is part
  of the fdisk package.  Remove the sfdisk call, and the failure does
  not happen, at least in my test setup.

  A call to sfdisk in a script causes a failure of a later series of
  calls to lsblk, in which lsblk fails to return information.

  I know sfdisk is designed for humans, but I'm wanting to automate the
  operation of its --backup option, and don't know of another way.  In
  any event, this failure shoudl be addressed.

  I'm attaching a script with illustrates both the problem and a
  workaround.  The workaround is to introduce a "sleep 1" call in
  between the calls to lsblk.  I can't even imagine why this works, but
  it does in my configuration.  I call the script with the name of a
  device which contains two ntfs partitions, and the name of a directory
  where results are to be stored.  The directory must contain a
  "clone.log" file (it can be empty; it's just to make sure I'm naming
  the correct directory).

  If I call it so it fails:
     bash b5.sh sda /tmp
  because the final lsblk call does not return any information

  However, if I call is to, it succeeds:
     bash -s b5.sh sda /tmp
  because the "-s" switch introduces a "sleep 1" call between lsblk calls.

  This makes no sense, which is why I consider it a bug.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: util-linux 2.31.1-0.4ubuntu3.6
  ProcVersionSignature: Ubuntu 4.15.0-101.102-generic 4.15.18
  Uname: Linux 4.15.0-101-generic x86_64
  NonfreeKernelModules: wl
  ApportVersion: 2.20.9-0ubuntu7.15
  Architecture: amd64
  Date: Sun Jun 14 09:36:17 2020
  SourcePackage: util-linux
  UpgradeStatus: No upgrade log present (probably fresh install)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1883441/+subscriptions