Running GNU coreutils via Homebrew on your Mac? Here's a one-liner to get the manpages working!

osx-brew-gnu-coreutils-man.sh

# Short of learning how to actually configure OSX, here's a hacky way to use
# GNU manpages for programs that are GNU ones, and fallback to OSX manpages otherwise
alias man='_() { echo $1; man -M $(brew --prefix)/opt/coreutils/libexec/gnuman $1 1>/dev/null 2>&1;  if [ "$?" -eq 0 ]; then man -M $(brew --prefix)/opt/coreutils/libexec/gnuman $1; else man $1; fi }; _'

Additionally, if one wants to make it available system-wide, one could add the lines to
/etc/paths
/etc/manpaths
Where /usr/libexec/path_helper would include them.

    $> PA1="$(brew --prefix coreutil)/libexec/" ;
    $> : ; # expand slashes (for sed use)
    $> BINPA ="${PA1//\//\\/}gnubin" ;
    $> MANPA ="${PA1//\//\\/}gnuman" ;
    $> : ; # put as first line
    $> sudo sed -i'' -e '1s/^/'"${BINPA}"'\n/' /etc/paths ;
    $> sudo sed -i'' -e '1s/^/'"${MANPA}"'\n/' /etc/manpaths ;

This solution makes the [section] argument for man fail to work.
e.g:
man 2 read can not find the man page for read in section 2.

Not one to settle for hacky work-arounds, I did a bit of googling and eventually found this solution to work for adding the gnu manpages:

1. Open the file /etc/man.conf
2. Add a line:

MANPATH_MAP /usr/local/opt/coreutils/libexec/gnubin /usr/local/opt/coreutils/libexec/gnuman

Hope that helps!

Strange bug for me. Once i use man ... sudo is aliased to that function.

@JacobDorman Do you use oh-my-zsh or prezto? There is an alias for sudo(!) which causes this failure. So try to comment out the line alias _='sudo' or add a line with unalias _ before the man alias.

The alias is not working with bash.

@tasmo Ahh so there is. I never use that. unalias _ fixes the issue.

What's wrong with just putting /usr/local/opt/coreutils/libexec/gnuman at the front of $MANPATH?

I have the same question as @OJFord. Why not just export MANPATH="/usr/local/opt/coreutils/libexec/gnuman:$MANPATH"?

man section will not work, use $@ instead of $1

alias man='_() { echo $@; man -M $(brew --prefix)/opt/coreutils/libexec/gnuman $@ 1>/dev/null 2>&1;  if [ "$?" -eq 0 ]; then man -M $(brew --prefix)/opt/coreutils/libexec/gnuman $@; else man $@; fi }; _'

This man hack command now not working in macOS 12.3.1 .. when i put this in my alias file and try to type man it stuck on "ma" only.. shall we have new workaround