Well, the /etc/mtab part in the cdrom LFS file turns out to overwrite the symlink created
by stage2. Fixed in commit 9a271cf7a8886c09854bdd69e636f1ef56280b1d - as I told you. :-)

> Hello Michael,
> 
> thanks for reporting this.
> 
> I'll investigate and get back to you later, if necessary.
> 
> Thanks, and best regards,
> Peter Müller
> 
> 
>> Hello,
>>
>> I just installed the latest nightly build from the ISO image and /etc/mtab is a regular file.
>>
>> Please see the attached screenshot.
>>
>>
>>
>> -Michael
>>
>>> On 12 Apr 2022, at 13:13, Michael Tremer <michael.tremer(a)ipfire.org> wrote:
>>>
>>> Hello,
>>>
>>>> On 12 Apr 2022, at 13:01, Peter Müller <peter.mueller(a)ipfire.org> wrote:
>>>>
>>>> Hello Michael,
>>>>
>>>>> Hello,
>>>>>
>>>>>> On 11 Apr 2022, at 20:14, Peter Müller <peter.mueller(a)ipfire.org> wrote:
>>>>>>
>>>>>> mount, as updated via util-linux, no longer writes /etc/mtab, causing
>>>>>> programs to rely on this file's content (such as the check_disk Nagios
>>>>>> plugin) to stop working.
>>>>>>
>>>>>> /proc/self/mounts contains all the necessary information, so it is fine
>>>>>> to replace /etc/mtab by a symlink to it.
>>>>>>
>>>>>> Fixes: #12843
>>>>>>
>>>>>> Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
>>>>>> ---
>>>>>> config/rootfiles/core/167/update.sh | 4 ++++
>>>>>> lfs/cdrom | 4 ++--
>>>>>> lfs/stage2 | 3 ++-
>>>>>> src/initscripts/system/mountfs | 6 ------
>>>>>> src/initscripts/system/partresize | 6 ------
>>>>>> 5 files changed, 8 insertions(+), 15 deletions(-)
>>>>>>
>>>>>> diff --git a/config/rootfiles/core/167/update.sh b/config/rootfiles/core/167/update.sh
>>>>>> index fdcb843cf..a9be60a1d 100644
>>>>>> --- a/config/rootfiles/core/167/update.sh
>>>>>> +++ b/config/rootfiles/core/167/update.sh
>>>>>> @@ -337,6 +337,10 @@ hardlink -c -vv /lib/firmware
>>>>>> # Regenerate all initrds
>>>>>> dracut --regenerate-all --force
>>>>>>
>>>>>> +# Replace /etc/mtab by symlink as mount no longer writes it
>>>>>> +rm -vf /etc/mtab
>>>>>> +ln -vs /proc/self/mounts /etc/mtab
>>>>>
>>>>> Okay. This would work.
>>>>
>>>> this sounds like you would have done that in another way...
>>>
>>> No, I just wanted to say something positive and as you know I don’t do this very often, so I am not very good at it :)
>>>
>>> This is the way to go.
>>>
>>>>>
>>>>>> +
>>>>>> # Rebuild IPS rules
>>>>>> perl -e "require '/var/ipfire/ids-functions.pl'; &IDS::oinkmaster();"
>>>>>> /etc/init.d/suricata reload
>>>>>> diff --git a/lfs/cdrom b/lfs/cdrom
>>>>>> index f35ff6a35..d84f8c23c 100644
>>>>>> --- a/lfs/cdrom
>>>>>> +++ b/lfs/cdrom
>>>>>> @@ -1,7 +1,7 @@
>>>>>> ###############################################################################
>>>>>> # #
>>>>>> # IPFire.org - A linux based firewall #
>>>>>> -# Copyright (C) 2007-2021 IPFire Team <info(a)ipfire.org> #
>>>>>> +# Copyright (C) 2007-2022 IPFire Team <info(a)ipfire.org> #
>>>>>> # #
>>>>>> # This program is free software: you can redistribute it and/or modify #
>>>>>> # it under the terms of the GNU General Public License as published by #
>>>>>> @@ -149,7 +149,7 @@ $(TARGET) : $(patsubst %,$(DIR_DL)/%,$(objects))
>>>>>>
>>>>>> 	# Clear mtab (prevents .journal problems)
>>>>>> 	rm -vf /etc/mtab
>>>>>> -	echo > /etc/mtab
>>>>>> +	ln -s /proc/self/mounts /etc/mtab
>>>>>
>>>>> This however should not be required.
>>>>
>>>> Where does the symlink then come from on new installations?
>>>
>>> It will be part of the regular image like all the other symlinks, too.
>>>
>>> -Michael
>>>
>>>>
>>>> Thanks, and best regards,
>>>> Peter Müller
>>>>
>>>>>
>>>>> Shipping the symlink should be enough. It would be great to get rid of hacks like these.
>>>>>
>>>>>> 	# Create filelist for packaging.
>>>>>> 	BUILDTARGET="$(BUILDTARGET)" BUILD_ARCH="$(BUILD_ARCH)" KVER="$(KVER)" \
>>>>>> diff --git a/lfs/stage2 b/lfs/stage2
>>>>>> index 9f93babe2..39697a848 100644
>>>>>> --- a/lfs/stage2
>>>>>> +++ b/lfs/stage2
>>>>>> @@ -87,7 +87,8 @@ endif
>>>>>> 	cp -rvf $(DIR_SRC)/config/etc/* /etc;
>>>>>> 	[ ! -d "$(DIR_SRC)/config/etc-$(BUILD_ARCH)" ] || cp -rvf $(DIR_SRC)/config/etc-$(BUILD_ARCH)/* /etc
>>>>>> 	cp -rvf $(DIR_SRC)/config/lib/* /lib;
>>>>>> -	touch /etc/{fs,m}tab
>>>>>> +	touch /etc/fstab
>>>>>> +	ln -s /proc/self/mounts /etc/mtab
>>>>>> 	echo "$(NAME) v$(VERSION) - $(SLOGAN)" > /etc/issue
>>>>>> 	echo "===============================" >> /etc/issue
>>>>>> 	echo "\n running on \s \r \m" >> /etc/issue
>>>>>> diff --git a/src/initscripts/system/mountfs b/src/initscripts/system/mountfs
>>>>>> index b1533d6a2..81ed729c1 100644
>>>>>> --- a/src/initscripts/system/mountfs
>>>>>> +++ b/src/initscripts/system/mountfs
>>>>>> @@ -31,12 +31,6 @@ case "${1}" in
>>>>>> 		# Remove fsck-related file system watermarks.
>>>>>> 		rm -f /fastboot /forcefsck
>>>>>>
>>>>>> -		boot_mesg "Create /etc/mtab..."
>>>>>> -		> /etc/mtab
>>>>>> -		mount -f / || failed=1
>>>>>> -		(exit ${failed})
>>>>>> -		evaluate_retval
>>>>>> -
>>>>>> 		# This will mount all filesystems that do not have _netdev in
>>>>>> 		# their option list. _netdev denotes a network filesystem.
>>>>>> 		boot_mesg "Mounting remaining file systems..."
>>>>>> diff --git a/src/initscripts/system/partresize b/src/initscripts/system/partresize
>>>>>> index 7605b9e2b..147405e1e 100644
>>>>>> --- a/src/initscripts/system/partresize
>>>>>> +++ b/src/initscripts/system/partresize
>>>>>> @@ -30,12 +30,6 @@ case "${1}" in
>>>>>> 			mount -o remount,rw / > /dev/null
>>>>>> 			evaluate_retval
>>>>>>
>>>>>> -			boot_mesg "Create /etc/mtab..."
>>>>>> -			> /etc/mtab
>>>>>> -			mount -f / || failed=1
>>>>>> -			(exit ${failed})
>>>>>> -			evaluate_retval
>>>>>> -
>>>>>> 			# check if serial console enabled
>>>>>> 			scon="off";
>>>>>> 			if [ ! "$(grep "console=ttyS0" /proc/cmdline)" == "" ]; then
>>>>>> -- 
>>>>>> 2.34.1
>>
>>