% which deroff
deroff: Command not found.
% pkg provides bin/deroff
Name    : plan9port-20220913
Comment : Plan 9 from User Space
Repo    : FreeBSD
Filename: usr/local/plan9/bin/deroff

Name    : heirloom-070715_4
Comment : Collection of standard Unix utilities
Repo    : FreeBSD
Filename: usr/local/heirloom/usr/5bin/deroff
% pkg search -oq plan9port 
devel/plan9port
% pkg search -oq heirloom
sysutils/heirloom
devel/heirloom-devtools
textproc/heirloom-doctools
mail/heirloom-mailx
shells/heirloom-sh
% sudo pkg install sysutils/heirloom
grahamperrin's password:
Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
Updating poudriere repository catalogue...
Fetching meta.conf: 100%    163 B   0.2kB/s    00:01    
Fetching packagesite.pkg: 100%  101 KiB 103.9kB/s    00:01    
The provides database is up-to-date.
Processing entries: 100%
poudriere repository update completed. 408 packages processed.
All repositories are up to date.
The following 2 package(s) will be affected (of 0 checked):

New packages to be INSTALLED:
        heirloom: 070715_4 [FreeBSD]
        pdksh: 5.2.14p2_6 [FreeBSD]

Number of packages to be installed: 2

The process will require 6 MiB more space.
1 MiB to be downloaded.

Proceed with this action? [y/N]: y
[1/2] Fetching heirloom-070715_4.pkg: 100%    1 MiB   1.1MB/s    00:01    
[2/2] Fetching pdksh-5.2.14p2_6.pkg: 100%  156 KiB 160.2kB/s    00:01    
Checking integrity... done (0 conflicting)
[1/2] Installing pdksh-5.2.14p2_6...
[1/2] Extracting pdksh-5.2.14p2_6: 100%
[2/2] Installing heirloom-070715_4...
[2/2] Extracting heirloom-070715_4: 100%
% man deroff
No manual entry for deroff
% which deroff
deroff: Command not found.
% pkg info --list heirloom | grep deroff
        /usr/local/heirloom/usr/5bin/deroff
        /usr/local/heirloom/usr/share/man/5man/man1/deroff.1
        /usr/local/heirloom/usr/share/man/5man/man1b/deroff.1b
        /usr/local/heirloom/usr/ucb/deroff
% man /usr/local/heirloom/usr/share/man/5man/man1/deroff.1
% man /usr/local/heirloom/usr/share/man/5man/man1b/deroff.1b
% history -S
% man -P cat /usr/local/heirloom/usr/share/man/5man/man1/deroff.1 | head -n 8
DEROFF(1)                        User Commands                       DEROFF(1)

NAME
       deroff - remove nroff/troff, tbl, and eqn constructs

SYNOPSIS
       deroff [-mx] [-w] [-xN] [ files ]

% man -P cat /usr/local/heirloom/usr/share/man/5man/man1b/deroff.1b | head -n 8
DEROFF(1B)                 BSD System Compatibility                 DEROFF(1B)

NAME
       deroff - (BSD) remove nroff, troff, tbl and eqn constructs

SYNOPSIS
       /usr/local/heirloom/usr/ucb/deroff [-w] file ...

% file /usr/local/heirloom/usr/5bin/deroff
/usr/local/heirloom/usr/5bin/deroff: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 14.0 (1400093), FreeBSD-style, stripped
% file /usr/local/heirloom/usr/ucb/deroff
/usr/local/heirloom/usr/ucb/deroff: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 14.0 (1400093), FreeBSD-style, stripped
% /usr/local/heirloom/usr/5bin/deroff /usr/src/share/man/man8/rc.8 | less
% /usr/local/heirloom/usr/ucb/deroff /usr/src/share/man/man8/rc.8 | less 
% /usr/local/heirloom/usr/5bin/deroff /usr/src/share/man/man8/rc.8 | grep -e Cm -e Li -e Nm -e Pa
% /usr/local/heirloom/usr/ucb/deroff /usr/src/share/man/man8/rc.8 | grep -e Cm -e Li -e Nm -e Pa
  Operation of Nm
  autoboot Ns  Ns Li yes
  Va rc_fast Ns  Ns Li yes ,
  rc_fast Ns  Ns Li yes
  Li nojail
  Li nojailvnet
  Li firstboot
  Li nostart
  Li start ,
  Operation of Nm rc.shutdown
  Li unspecified
  Li shutdown
  Li faststop ,
  Contents of Nm rc.d/
    .Pa ALLUPPERCASE  indent
  Pa ALLUPPERCASE
    .Pa FILESYSTEMS 
  Pa FILESYSTEMS
  Pa NETWORKING
  Pa SERVERS
  Pa DAEMON
  Pa LOGIN
  Pa bar
  Li PROVIDE
  Li REQUIRE
  Li BEFORE
    .Cm restart  indent
  Cm start
  Cm stop
  Cm restart
  Cm status
  Cm enable
  Cm disable
  Cm delete
  Li service_delete_empty
  Li YES ,
  Cm describe
  Cm extracommands
  Cm poll
  Cm enabled
  Cm rcvar
  Li start
  Li stop
  Cm open
  Cm client
  Cm simple
  Cm closed
  Cm UNKNOWN
     Pa
  Pa 
  Pa 
  Pa 
  Pa 
  Pa 
  Pa 
  Pa 
  Pa 
  Pa 
% man -P less /usr/src/share/man/man8/rc.8 
% cat /usr/src/share/man/man8/rc.8 | grep Operation\ of
.Ss Operation of Nm
.Ss Operation of Nm rc.shutdown
% /usr/local/heirloom/usr/5bin/deroff /usr/src/share/man/man8/rc.8 | grep Operation
 Operation  
 Operation   rc.shutdown
%