How to replace Mac OS X utilities with GNU core utilities?

Besides brew install coreutils, you may also need to install some other packages, such as gnu-sed, grep (some of the packages require you to run brew tap homebrew/dupes first):

brew install findutils --with-default-names
brew install gnu-indent --with-default-names
brew install gnu-sed --with-default-names
brew install gnutls
brew install grep --with-default-names
brew install gnu-tar --with-default-names
brew install gawk

The --default-names option is optional, turn on this if you really need to use these GNU commands as default ones, or they will be compiled with a g prefix.

Reference: http://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x/

I'm not sure that I would recommend replacing them; however, you can install them to a different path and utilize them that way. Overall, if you are coming from Linux and would like access to more "generic" *nix utilities, and a system similar to apt, then I would recommend looking into Macports: http://www.macports.org

It allows, for example, using the latest "generic" GCC, as opposed to/in addition to Apple's included GCC, just as an example.

I've written a script to do exactly this! The script can be viewed here (or below). However, I can't always guarantee this post will reflect the latest version of the script linked previously.

Upon running the script, Homebrew will be installed (if not already), all the associated GNU utilities will be installed (if not already), and the PATH variable will be built from the installed utilities.

#!/bin/bash

# Install Homebrew (if not already installed)
ruby -e "$(curl -fsSL "\
"https://raw.githubusercontent.com/Homebrew/install/master/install)"

# Install required packages from Homebrew
brew tap homebrew/dupes
brew install coreutils binutils diffutils ed findutils gawk gnu-indent gnu-sed \
  gnu-tar gnu-which gnutls grep gzip screen watch wdiff wget bash gdb gpatch \
  m4 make nano file-formula git less openssh python rsync svn unzip vim \
  --default-names --with-default-names --with-gettext --override-system-vi \
  --override-system-vim --custom-system-icons

# Empty the .bash_path file that holds GNU paths
> ~/.bash_path

# Build PATH variable script in ~/.bash_path
for i in /usr/local/Cellar/*/*/bin; do
  echo 'export PATH="'$i':$PATH"' >> ~/.bash_path
done
for i in /usr/local/Cellar/*/*/libexec/gnubin; do
  echo 'export PATH="'$i':$PATH"' >> ~/.bash_path
done
for i in /usr/local/Cellar/*/*/share/man; do
  echo 'export MANPATH="'$i':$MANPATH"' >> ~/.bash_path
done
for i in /usr/local/Cellar/*/*/libexec/gnuman; do
  echo 'export MANPATH="'$i':$MANPATH"' >> ~/.bash_path
done

# Check if .bash_path is being called from .bash_profile
PATCH=`grep "~/.bash_path" ~/.bash_profile`
if [ "$PATCH" == "" ]; then
  # Add Ubuntu-style PS1 to .bash_profile
  cat <<EOF > ~/.bash_profile
export PS1="\[\033[1;32m\]\u@\h\[\033[0m\]:\[\033[1;34m\]\w\[\033[0m\]# "
EOF
  # Add .bash_path to .bash_profile
  echo "source ~/.bash_path" >> ~/.bash_profile
fi