Insert the SD card
Check for automatically mounted volumes
$ ls /Volumes/
MacBookSSD boot
Identify mounted volumes
$ diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *480.1 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS MacBookSSD 479.2 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
/dev/disk1 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *31.9 GB disk1
1: Windows_FAT_32 boot 43.7 MB disk1s1
2: Linux 31.9 GB disk1s2
Unmount mounted volume
$ sudo umount /dev/disk1s1
Write the image to the SD card
$ sudo dd if=2017-07-05-raspbian-jessie-lite.img of=/dev/disk1 bs=1m
If you want to check the progress, press ctrl+t
$ diskutil eject /dev/disk1