discussion on future removal of empty $FreeBSD$ tags

Dear subscribers,

after one of the recent commits[1] surprisingly we got rid of $FreeBSD$ 
from among others, two configuration files: /etc/ssh/ssh_config and 
/etc/ssh/sshd_config. I was told these IDs are going to be deprecated in 
the whole source tree when 12.x branch reaches EoL, what is surprising 
news, at least for me. While indeed empty $FreeBSD$ tags after the 
transition to git became useless, leaving them in config files, still 
might be handy. Please let me explain why.

After the transition to git, a lot of people complained about breakage 
in mergemaster(8). Finally, they were told that this tool is outdated, 
cannot do 3-way merge, has no maintainer, etc. so it's going to be 
deprecated soon. Then appropriate notice was added, the handbook got 
updated, so seemingly everyone was fine with this depreciation. I am not 
going to bring any serious arguments against etcupdate(8), but when 
providing support on IRC, a few cases of foot shooting with this tool 
had been reported to me and the last one happened this year IIRC. 
Moreover some people, including me, just like and are used to old 
sdiff(1)-way work of mergemaster(8).  So soon after the transition to 
git to overcome this deficiency I wrote for myself a git primer helping 
with quick creation of local repository including $FreeBSD$ recreation 
for mergemaster(8) relying on empty $FreeBSD$ tags. I will attach this 
primer[2] for users here, maybe someone (noncommitter) will benefit from 
this (if it will not get burned with fire here earlier).

Please don't get me wrong, I am not fighting with etcupdate(8) which 
works almost flawlessly in unison with freebsd-update(8), but people who 
follow STABLE/CURRENT really do appreciate the existence of 
mergemaster(8) and still use it behind the scenes, including probably 
members of core@ team. I am only asking for leaving these empty 
$FreeBSD$ IDs in config files. This will of course add some burden to 
committers' work but might be beneficial in the future. I am neither 
committer, nor contributor, but the voice from the userbase.

Best regards,

Marek Zarychta

[1] https://cgit.freebsd.org/src/commit/?id=835ee05f

[2]

########################################################
#
# FreeBSD Git src with worktrees and clean/smudge filters
# for mergemaster(8)
#
########################################################
# Preparation of the tree

zfs create zroot/usr/src_head
zfs create zroot/usr/src_13

########################################################
# Making src of stable/13 mountable in /usr/src
  
echo "/usr/src_13 	/usr/src 		nullfs rw,late 0 0" >> /etc/fstab
mount -al

########################################################
# Cloning the repository

cd /usr/src_head
git clonehttps://git.freebsd.org/src.git/  ./

########################################################
# Adding filters
# Filters require lang/ruby and lang/perl installed

git config filter.freebsdid.smudge expand_freebsd
git config filter.freebsdid.clean 'perl -pe "s/\\\$FreeBSD[^\\\$]*\\\$/\\\$FreeBSD\\\$/"'

########################################################
# Limiting filters scope
# In /usr/src_head create file .git/info/attributes with
# following contents (at least):

------------cut------------
cat > .git/info/attributes << EOF
etc/* 	                filter=freebsdid
etc/*/*                 filter=freebsdid
libexec/rc/*            filter=freebsdid
libexec/rc/rc.d/*       filter=freebsdid
*.conf                  filter=freebsdid
dot.??*                 filter=freebsdid
lib/libc/gen/shells     filter=freebsdid
lib/libc/net/hosts      filter=freebsdid
lib/libpam/pam.d/*      filter=freebsdid
lib/libwrap/hosts.allow filter=freebsdid
usr.sbin/services_mkdb/services filter=freebsdid
usr.sbin/bsnmpd/bsnmpd/snmpd.config filter=freebsdid
usr.sbin/periodic/etc/* filter=freebsdid
usr.sbin/cron/cron/crontab filter=freebsdid
crypto/openssh/ssh*_config filter=freebsdid
EOF
------------cut------------

########################################################
# Smudge filter setup
# Create file /usr/local/bin/expand_freebsd with following
# contents and make it executable.

------------cut------------
#!/usr/bin/env ruby
data = STDIN.read
last_info = `git log --pretty=format:"%h %ae %ad" -1`
puts data.gsub('$FreeBSD$', '$FreeBSD: ' + last_info.to_s + '$')
------------cut------------

chmod a+x /usr/local/bin/expand_freebsd

########################################################
# Adding worktrees
# Add worktree for stable/13, filters will be applied

git worktree add /usr/src_13 stable/13

# To have IDs in main (HEAD)
# do checkout of filtered files again

cd /usr/src_head
rm etc/master.passwd etc/group
rm libexec/rc/rc.d/*
git checkout -f -- .

########################################################
# To find more files with $FreeBSD tags which might
# be added to .git/info/attributes file issue command:

find . -type f -a -not -name '*~' | xargs grep -l '$FreeBSD'

-- 
Marek Zarychta