How to use GNU sed on Mac OS 10.10+, 'brew install --default-names' no longer supported

Under Mac OS 10.10.3, I installed gnu-sed by typing:

brew install gnu-sed --default-names

When I type it again, I get the message:

gnu-sed-4.2.2 already installed

However, even after rebooting the system and restarting Terminal, I still cannot use the GNU version of sed. For example:

echo a | sed ’s_A_X_i’

returns: bad flag in substitution command 'i'

What should I do to get the GNU version working? Here are the paths in my $PATH variable.

/Users/WN/-myUnix
/opt/local/bin
/opt/local/sbin
/usr/bin
/bin
/usr/sbin
/sbin
/usr/local/bin
/Applications/calibre.app/Contents/MacOS
/opt/ImageMagick/bin
/usr/texbin 

I'm sorry if my question seems obvious, but I am learning shell scripting on my own and don't quite understand yet how UNIX programs are installed. Any help to use GNU compliant commands (in this case sed, but soon I'll need others as well) on my Mac without causing damage or unnecessary clutter would be greatly appreciated.

Note (2019):

The --with-default-names option is removed since January 2019, so now that option is not available anymore.

When installing, Homebrew instructs on how to adapt the path, if one wants to use sed without the g prefix.

---

You already have the gnu-sed installed without the --with-default-names option.

• With --with-default-names option it installs sed to /usr/local/bin/
• Without that option it installs gsed

So in your case what you gotta do is:

$ brew uninstall gnu-sed
$ brew install gnu-sed --with-default-names

Update path if needed...

$ echo $PATH | grep -q '/usr/local/bin'; [ $? -ne 0 ] && export PATH=/usr/local/bin:$PATH
$ echo a | sed 's_A_X_i'

or use gsed as others suggested.

When you install the GNU version of sed for Mac OS X using:

$ brew install gnu-sed

The program that you use is gsed.

So for example:

$ echo "Calimero is a little chicken" > test
$ cat test
Calimero is a little chicken
$ gsed -i "s/little/big/g" test
$ cat test
Calimero is a big chicken

Also, to compliment the use of GNU command tools on Mac OS X, there is a nice blog post here to get the tools from linux:

[Install and use GNU command line tools on Mac OS/OS X][1]

[1]: https://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x/ "Install and Use GNU Command Line Tools on macOS/OS X"

$ brew install gnu-sed

$ export PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"

With these two commands gnu-sed works properly

The sed that ships with OS X is in /usr/bin.

The sed that homebrew installs is in /usr/local/bin.

If you prefer to use the homebrew one, you have two options:

Option 1

Every time you want to use homebrew sed, type

/usr/local/bin/sed

or, preferably

Option 2

Move /usr/local/bin/ ahead (i.e. before) /usr/bin in your PATH in your login profile, like this

 export PATH=/usr/local/bin:<other places>

If you need to use gnu-sed command with their normal names, you can add a "gnubin" directory to your PATH from your bashrc. Just use the following command in your bash or terminal.

export PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"

--with-default-names didn't work for me on Mac OS X 10.14.2 so I created a symlink named sed to gsed higher in the $PATH

I also created a symlink named sed.1 to the gsed.1 manpage higher in the $MANPATH so man would access the gsed manpage instead of the default sed manpage

this export PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"

is only valid per terminal SESSIOn as soon as you restart its GONE ( Mojave )

Since the --with-default-names option was removed in Jan. 2019, my hack solution is:

# hack to override mac tools with homebrew versions (ls, sed, etc)
for p in `find "${HOMEBREW_PREFIX}" -type d -name gnubin` ; do
    export PATH="${p}:${PATH}"
done

which is a little slow (crawling the dir every login) but works without forcing me to modify my .bashrc for every gnu tool I happen to install with brew.