I'm trying to get Arch Linux ARM onto my RasPi 2 by doing the instructions here under "Installation", but the commands are Linux commands, I am trying to format the SD with my Mac and so there are differences in the programs I'm trying to get around. For example sudo fdisk /dev/sdX on linux would result in an interactive prompt, on OSX it's different, instead I have to do fdisk -ie /dev/sdX to get an interactive prompt, and then the commands are different.
What I want to do on my mac is the same ad this process on linux:
Start fdisk to partition the SD card: fdisk /dev/sdX At the fdisk prompt, delete old partitions and create a new one:
Type o. This will clear out any partitions on the drive. Type p to list partitions. There should be no partitions left. Type n, then p for primary, 1 for the first partition on the drive, press ENTER to accept the default first sector, then type +100M for the last sector. Type t, then c to set the first partition to type W95 FAT32 (LBA). Type n, then p for primary, 2 for the second partition on the drive, and then press ENTER twice to accept the default first and last sector. Write the partition table and exit by typing w.
But I'm not sure how to achive this with OSX's fdisk.
I'm afraid it's not possible: you must use linux to install the tarball because you have to create an ext partition, which is not supported by OS X.
I had to reinstall Arch but I have just found out they don't distribute disk images anymore. Some possible solutions are explained in this answer.