Mac下用命令行制作Linux启动U盘

概述

家里有台闲置的Mac mini，我想给它装上linux系统做服务器用，以往我都是用软碟通(UltraISO)制作U盘启动盘。这次试下在Mac下用命令行做启动盘，本文记录整个过程。

下载linux镜像

ubuntu: https://ubuntu.com/#download
centos: https://www.centos.org/download/
都可以
下载iso格式的

格式化u盘

参考 Mac下用命令行格式化U盘

将iso文件转换为img文件

命令

hdiutil convert -format UDRW -o /path/to/target.img /path/to/source.iso

执行命令情况

$ hdiutil convert -format UDRW -o ubuntu.img ubuntu.iso
Reading Driver Descriptor Map (DDM : 0)…
Reading Ubuntu 16.04.6 LTS amd64         (Apple_ISO : 1)…
Reading Apple (Apple_partition_map : 2)…
Reading Ubuntu 16.04.6 LTS amd64         (Apple_ISO : 3)…
.............................................................................................................................................................................................................
Reading EFI (Apple_HFS : 4)…
.............................................................................................................................................................................................................
Reading Ubuntu 16.04.6 LTS amd64         (Apple_ISO : 5)…
...............................................................................................................................................................................................................
Elapsed Time:  3.968s
Speed: 400.0Mbytes/sec
Savings: 0.0%
created: /Users/shiming/Downloads/ubuntu.img.dmg

注意：
命令执行完后，ubuntu.img文件后面会自动加上.dmg后缀，要将它删掉

mv ubuntu.img.dmg ubuntu.img

确定U盘挂载点

执行diskutil list确定U盘挂载点

$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         500.0 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD - Data     376.4 GB   disk1s1
   2:                APFS Volume Preboot                 80.9 MB    disk1s2
   3:                APFS Volume Recovery                526.6 MB   disk1s3
   4:                APFS Volume VM                      7.5 GB     disk1s4
   5:                APFS Volume Macintosh HD            11.0 GB    disk1s5

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *8.0 GB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:       Microsoft Basic Data UDISK                   7.8 GB     disk2s2

/dev/disk2就是，因为他是external的，且大小和我插入的U盘一致

取消挂载

使用命令diskutil unmountDisk /dev/diskN取消挂载, diskN是上一个步骤确定的U盘

$ diskutil unmountDisk /dev/disk2
Unmount of all volumes on disk2 was successful

制作引导盘

使用命令sudo dd if=/path/to/downloaded.img of=/dev/diskN bs=1m制作引导盘

这个命令执行时比较长，1.6G的文件，大概执行了15分钟

$ sudo dd if=ubuntu.img of=/dev/disk2 bs=1m
1587+1 records in
1587+1 records out
1664614400 bytes transferred in 922.708091 secs (1804053 bytes/sec)

参考资料

How to Erase a Disk from Command Line in Mac OS X
How to make a bootable usb stick from an iso file on an apple mac os x