Modify for GNU coreutils:
1. Modify /Users/icarus4/.rbenv/shims:/Users/icarus4/bin:/Users/icarus4/usr/bin:/usr/local/opt/coreutils/libexec/gnubin:/usr/local/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
2. Add MANPATH
3. ls --color