[Bug 2147120] [NEW] "tail -0f <file> makes tail core-dump
Oliver Nissen
2147120 at bugs.launchpad.net
Thu Apr 2 14:05:14 UTC 2026
Public bug reported:
1) The release of Ubuntu you are using, via 'lsb_release -rd' or System
-> About Ubuntu
lsb_release -rd
Description: Ubuntu 25.10
Release: 25.10
2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
apt list coreutils
coreutils/questing,questing,now 9.5-1ubuntu2+0.0.0~ubuntu24 all [installed]
3) What you expected to happen
When issuing a tail -0f /var/log/syslog I expect tail to start with no
output at all until the "tailed" file changes; then the newly added
lines should be displayed.
4) What happened instead
When if run tail -0f <file> I receive an error, e.g.:
--
> tail -0f /var/log/syslog
thread 'main' panicked at src/uu/tail/src/tail.rs:393:17:
assertion `left == right` failed
left: 1
right: 0
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted (core dumped)
--
As suggested, I did an
> export RUST_BACKTRACE=full
and the resulting output is:
--
> tail -0f /var/log/syslog
thread 'main' panicked at src/uu/tail/src/tail.rs:393:17:
assertion `left == right` failed
left: 1
right: 0
stack backtrace:
0: 0x5a4ecd015db9 - <unknown>
1: 0x5a4ecce20913 - <unknown>
2: 0x5a4ecd001fff - <unknown>
3: 0x5a4ecd015c13 - <unknown>
4: 0x5a4eccfde7c3 - <unknown>
5: 0x5a4eccfde5b6 - <unknown>
6: 0x5a4eccfdee0c - <unknown>
7: 0x5a4ecd016b0a - <unknown>
8: 0x5a4ecd015fd9 - <unknown>
9: 0x5a4eccfde8fd - <unknown>
10: 0x5a4eccd83690 - <unknown>
11: 0x5a4eccd83a43 - <unknown>
12: 0x5a4eccd838fa - <unknown>
13: 0x5a4ecd1cfb41 - <unknown>
14: 0x5a4ecd1ce469 - <unknown>
15: 0x5a4ecce362f1 - <unknown>
16: 0x5a4ecce38f8f - <unknown>
17: 0x5a4ecce6cab4 - <unknown>
18: 0x5a4ecce746f7 - <unknown>
19: 0x5a4ecd0019f7 - <unknown>
20: 0x5a4ecce746e5 - <unknown>
21: 0x7af09002a575 - __libc_start_call_main
at ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
22: 0x7af09002a628 - __libc_start_main_impl
at ./csu/../csu/libc-start.c:360:3
23: 0x5a4eccd93b15 - <unknown>
24: 0x0 - <unknown>
Aborted (core dumped)
--
ProblemType: Bug
DistroRelease: Ubuntu 25.10
Package: coreutils-from-uutils 0.0.0~ubuntu24
ProcVersionSignature: Ubuntu 6.17.0-20.20-generic 6.17.13
Uname: Linux 6.17.0-20-generic x86_64
ApportVersion: 2.33.1-0ubuntu3
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: XFCE
Date: Thu Apr 2 15:47:18 2026
InstallationDate: Installed on 2021-10-08 (1637 days ago)
InstallationMedia: Ubuntu 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819)
PackageArchitecture: all
SourcePackage: coreutils-from
UpgradeStatus: Upgraded to questing on 2025-11-17 (136 days ago)
** Affects: coreutils-from (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug questing
--
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https://bugs.launchpad.net/bugs/2147120
Title:
"tail -0f <file> makes tail core-dump
Status in coreutils-from package in Ubuntu:
New
Bug description:
1) The release of Ubuntu you are using, via 'lsb_release -rd' or
System -> About Ubuntu
lsb_release -rd
Description: Ubuntu 25.10
Release: 25.10
2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
apt list coreutils
coreutils/questing,questing,now 9.5-1ubuntu2+0.0.0~ubuntu24 all [installed]
3) What you expected to happen
When issuing a tail -0f /var/log/syslog I expect tail to start with no
output at all until the "tailed" file changes; then the newly added
lines should be displayed.
4) What happened instead
When if run tail -0f <file> I receive an error, e.g.:
--
> tail -0f /var/log/syslog
thread 'main' panicked at src/uu/tail/src/tail.rs:393:17:
assertion `left == right` failed
left: 1
right: 0
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted (core dumped)
--
As suggested, I did an
> export RUST_BACKTRACE=full
and the resulting output is:
--
> tail -0f /var/log/syslog
thread 'main' panicked at src/uu/tail/src/tail.rs:393:17:
assertion `left == right` failed
left: 1
right: 0
stack backtrace:
0: 0x5a4ecd015db9 - <unknown>
1: 0x5a4ecce20913 - <unknown>
2: 0x5a4ecd001fff - <unknown>
3: 0x5a4ecd015c13 - <unknown>
4: 0x5a4eccfde7c3 - <unknown>
5: 0x5a4eccfde5b6 - <unknown>
6: 0x5a4eccfdee0c - <unknown>
7: 0x5a4ecd016b0a - <unknown>
8: 0x5a4ecd015fd9 - <unknown>
9: 0x5a4eccfde8fd - <unknown>
10: 0x5a4eccd83690 - <unknown>
11: 0x5a4eccd83a43 - <unknown>
12: 0x5a4eccd838fa - <unknown>
13: 0x5a4ecd1cfb41 - <unknown>
14: 0x5a4ecd1ce469 - <unknown>
15: 0x5a4ecce362f1 - <unknown>
16: 0x5a4ecce38f8f - <unknown>
17: 0x5a4ecce6cab4 - <unknown>
18: 0x5a4ecce746f7 - <unknown>
19: 0x5a4ecd0019f7 - <unknown>
20: 0x5a4ecce746e5 - <unknown>
21: 0x7af09002a575 - __libc_start_call_main
at ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
22: 0x7af09002a628 - __libc_start_main_impl
at ./csu/../csu/libc-start.c:360:3
23: 0x5a4eccd93b15 - <unknown>
24: 0x0 - <unknown>
Aborted (core dumped)
--
ProblemType: Bug
DistroRelease: Ubuntu 25.10
Package: coreutils-from-uutils 0.0.0~ubuntu24
ProcVersionSignature: Ubuntu 6.17.0-20.20-generic 6.17.13
Uname: Linux 6.17.0-20-generic x86_64
ApportVersion: 2.33.1-0ubuntu3
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: XFCE
Date: Thu Apr 2 15:47:18 2026
InstallationDate: Installed on 2021-10-08 (1637 days ago)
InstallationMedia: Ubuntu 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819)
PackageArchitecture: all
SourcePackage: coreutils-from
UpgradeStatus: Upgraded to questing on 2025-11-17 (136 days ago)
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