homegnu.sh

#!/bin/echo Don't execute this script directly, source it into your shell.
# This script will attempt to make your macOS system behave more like GNU for shell scripts
#  by diverting as many commands as possible, to the GNU versions, provided by Homebrew
#
# For most Homebrew tools, their presence in /usr/local/bin and that being in your $PATH
#  means you can use them as-is, but some tools appear with different names because macOS
#  already has such a tool (e.g. find(1)). These tools generally also have a `gnubin` path
#  which we can use to make them higher priority than the macOS equivalents.
#
# To use this:
# 1) Install various GNU tools via homebrew, such as:
#   * coreutils
#   * gnu-getopt
#   * gnu-sed
#   * gawk
#   * gnu-tar
#   * gnu-time
#   * gnu-which
#   * moreutils
#   * num-utils
# 2) Load this script into your shell when you want to Go GNU:
#   * source /path/to/homegnu.sh
# 3) (optional extra) build something fancy into your $PS1 to detect $__HOMEGNU is set, to let you know commands are different now
# 4) Explore other packages that have gnubin paths: grep -rl gnubin /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/
# 5) To undo Homegnu, either set your $PATH back to normal, or just spawn a new shell/terminal

BREWROOT="/usr/local"
GNUPATH=""

while read -r gnubin ; do
    GNUPATH="${gnubin}:${GNUPATH}"
done < <(find -L "${BREWROOT}/opt" -type d -name gnubin)

export PATH="${GNUPATH}${PATH}"
export __HOMEGNU=1