To install Maven on OS X, go to the Apache Maven website and download the binary zip file.
You can then shift the apache-maven-3.0.5 folder in your Downloads folder to wherever you want to keep Maven; however as the rest of the process involves the command line, I recommend you do everything from there.
At the command line, you would run something like:
mv ~/Downloads/apache-maven-3.0.5 ~/Development/
This is just my personal preference - to have a "Development" directory in my home directory. You can choose something else if you wish.
Next, edit ~/.profile in the editor of your choice, and add the following:
export M2_HOME="/Users/johndoe/Development/apache-maven-3.0.5"
export PATH=${PATH}:${M2_HOME}/bin
The first line is important to Maven (and must be a full explcit path); the second line is important to the shell, in order to run the "mvn" binary. If you have a variation of that second line already in .profile, then simply add ${M2_HOME}/bin to the end of it.
Now open a second terminal window and run
mvn -version
which should give output like...
Apache Maven 3.0.5 (r01de14724cdef164cd33c7c8c2fe155faf9602da; 2013-02-19 13:51:28+0000)
Maven home: /Users/johndoe/Development/apache-maven-3.0.5
Java version: 1.7.0_40, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.7.0_40.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.9", arch: "x86_64", family: "mac"
Couple of things to note:
If you've installed the Oracle JDK 1.7, then you may find Maven reports JDK 1.6 in the above output. To solve this, add the following to your ~/.profile:
export JAVA_HOME=$(/usr/libexec/java_home)
As some have pointed out, Maven has historically been supplied either with OS X itself, or with the optional Command Line Tools for XCode. This may cease to be the case for future versions of OS X, and in fact OS X Mavericks does not include Maven. Personal opinion: This could be because they are still in beta, or it could be that Apple have taken a look at the latest Thoughtworks Technology Radar, and spotted that Maven has been moved to "Hold".
mvn
executable from your terminal window.