1. Check the U disk logo
liaojie@lj-mac-pro:~$diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *251.0 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk1 250.8 GB disk0s2
/dev/disk1 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +250.8 GB disk1
Physical Store disk0s2
1: APFS Volume Macintosh HD 216.1 GB disk1s1
2: APFS Volume Preboot 22.1 MB disk1s2
3: APFS Volume Recovery 509.8 MB disk1s3
4: APFS Volume VM 3.2 GB disk1s4
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *15.9 GB disk2
1: Windows_FAT_32 15.9 GB disk2s4
liaojie@lj-mac-pro:~$diskutil unmountDisk /dev/disk2
Unmount of all volumes on disk2 was successful
liaojie@lj-mac-pro:2. Write iso to usb
liaojie@lj-mac-pro:~$sudo dd if=/Users/liaojie/tmp/soft/CentOS-6.8-x86_64-bin-DVD1.iso of=/dev/disk2 bs=1m
Password:
3735+0 records in
3735+0 records out
3916431360 bytes transferred in 179.743862 secs (21788957 bytes/sec)
liaojie@lj-mac-pro:~$