Debian package build shows: date: invalid date '@'

[hdiethelm]

This happens on master and 2.9.

debuild -us -uc --build=any
 dpkg-buildpackage -us -uc -ui --build=any --build=any
dpkg-buildpackage: info: source package linuxcnc
dpkg-buildpackage: info: source version 1:2.10.0~pre1
dpkg-buildpackage: info: source distribution UNRELEASED
dpkg-buildpackage: info: source changed by andypugh <andy@bodgesoc.org>
 dpkg-source --before-build .
dpkg-buildpackage: info: host architecture amd64
 debian/rules clean
dh clean -D/linuxcnc/src
date: invalid date '@'
date: invalid date '@'
...

See for example here:
https://github.com/LinuxCNC/linuxcnc/actions/runs/25625174251/job/75218888138#step:7:9067

The issue is probably in these lines:
https://github.com/LinuxCNC/linuxcnc/blob/master/debian/rules.in#L31

Build just works fine but they might be hidden issues.

[BsAtHome]

That would suggest that TIMESTAMP=$(shell dpkg-parsechangelog -S timestamp) failed (line 29). That seems a bit odd, unless that executable is not available. Is dpkg-dev installed?

[hdiethelm]

Running dpkg-parsechangelog -S timestamp on the console gives me a big number, so this seams to be ok.

Removing line 30 and 31 and the error is gone. So there is something wrong there. I also did no see what but it might be a make variable set issue on line 29 or an expansion issue on 30/31.

[BsAtHome]

Running

#!/usr/bin/make -f

TIMESTAMP=$(shell dpkg-parsechangelog -S timestamp)
export DATE=$(shell LANG=C date --date="@$(TIMESTAMP)" '+%d\ %b\ %Y')
export TIME=$(shell LANG=C date --date="@$(TIMESTAMP)" '+%T')

all:
	echo "timestamp" "$(TIMESTAMP)"
	echo "date" "$(DATE)"
	echo "time" "$(TIME)"

Results in:

date: invalid date '@'
date: invalid date '@'
date: invalid date '@'
date: invalid date '@'
date: invalid date '@'
date: invalid date '@'
echo "timestamp" "1767824118"
date: invalid date '@'
date: invalid date '@'
timestamp 1767824118
echo "date" "07\ Jan\ 2026"
date 07\ Jan\ 2026
echo "time" "17:15:18"
time 17:15:18

Change the lines to:

TIMESTAMP=@$(shell dpkg-parsechangelog -S timestamp)
export DATE=$(shell LANG=C date --date="$(TIMESTAMP)" '+%d\ %b\ %Y')
export TIME=$(shell LANG=C date --date="$(TIMESTAMP)" '+%T')

[hdiethelm]

It might be worth investigating if DATE / TIME is used anywhere. This is probably broken since 5+ years according to git blame and no one noticed...

[BsAtHome]

It is actually much more simple than that!

In make there is a difference between '=' and ':=' assignment. The former is evaluated when it is used whereas the latter is only evaluated once when it is defined.

The correct fix should thus be:

TIMESTAMP:=$(shell dpkg-parsechangelog -S timestamp)
export DATE:=$(shell LANG=C date --date="@$(TIMESTAMP)" '+%d\ %b\ %Y')
export TIME:=$(shell LANG=C date --date="@$(TIMESTAMP)" '+%T')

The DATE/TIME are used in the build by debian and the tools to create a reproducible build and the binaries are the same regardless when they are built.

[BsAtHome]

Fixed in #4016.

[hdiethelm]

Thanks for fixing! :-)