This is very short version of the official guide^[1], focusing Raspberry Pi 2 (RPI2) without attached monitor and keyboard. It is need to be connected to the router though.

Prerequisites:

• Raspberry Pi model 2
• Micro SD card
• Wired connection to router
• DHCP enabled on the router
• Macbook with card reader

Start from downloading the latest Raspbian (Debian Linux for Raspberry Pi) from https://www.raspberrypi.org/downloads/raspbian/. The Lite version seems to be about right. Unzip the image.

Write it to SD card:

1. Identify SD card disk device name by running diskutil list. It should look like /dev/diskN where N is the disk id.
2. Unmount it by running diskutil unmountDisk /dev/diskN, where N is device id identified at 1. For example, diskutil unmountDisk /dev/disk2.
3. Copy the data by running sudo dd bs=1m if=image.img of=/dev/rdiskN. This will take a while. Press Ctrl+T to check the progress.
4. Enable ssh by creating file "ssh" in boot partition of the mounted SD card: touch /Volumes/boot/ssh.
5. Eject the card sudo diskutil eject /dev/rdisk2.

Insert SD card into RPI, connect RPI to the router and power it. In a minute check the list of connected devices and their IP addresses.

Connect to RPI with default username pi:

$ ssh pi@ipaddress

After asking to save host fingerprint, it should display password prompt. Use password raspberry.

You are in. That's typical Debian linux. Do nice things.