fdisk
fdisk [選項] <disk> 改變分區表
fdisk [選項] –l <disk> 列出所有分區表
fdisk –s <partition（分區編號）> 以分區塊為單位，給出指定分區的大小
這是一個創建和維護分區的命令，兼容DOS類型的分區表、BSD或SUN類型的磁盤列表。注意fdisk不支持2T以上的硬盤分區，此時需要使用gdisk。
相關了解：
磁頭數（Heads）表示硬盤有幾個磁頭，也就是有幾面盤片，一個硬盤最多有255個磁頭
柱面數（Cylinders）表示硬盤每面盤片上有幾條磁道
扇區數（Sectors）表示每條磁道上有幾個扇區，每條磁道最多有63個扇區
(1).選項
-b <size> 指定扇區大小（512，1024，2048或4096 B） -c 關閉DOS兼容模式 -u <size> 以扇區編號取代柱面編號來表示每個分區的起始地址，一般與-l選項聯合使用 -C <number> 指定柱面編號 -H <number> 指定磁頭編號 -S <number> 指定磁道扇區編號
(2).菜單操作說明：
a 設置可引導標記（活動分區/引導分區之間切換） b 編輯BSD磁盤標簽 c 設置DOS操作系統兼容標記（兼容/不兼容之間切換） d 刪除一個分區 l 顯示已知的分區類型，其中82為Linux swap分區，83為Linux分區 m 顯示幫助信息 n 增加一個新的分區 o 創建一個新的空白的DOS分區表 p 顯示磁盤當前的分區表 q 退出fdisk程序，不保存任何修改 s 創建一個新的空白的Sun磁盤標簽 t 改變一個分區的系統ID，就是改變分區類型（比如把Linux Swap分區改為Linux分區） u 改變顯示或輸入單位 v 驗證磁盤分區表 w 將分區表寫入磁盤並退出（保存並退出） x 額外功能（專家級）
(3).擴展
sda和hda的區別
sd代表的是SCSI，SATA接口硬盤 hd代表IDE接口的硬盤 sda和hda最后面的a都代表的是第一塊硬盤 sda1和hda1則代表的是該硬盤的第一分區
(4).實例
1）.使用-l選項，列出所有分區表
/*盤/dev/sda:107.4G,107374182400字節（B）,255個磁頭，63個扇區，13054柱面（磁道） * 1單位=16065柱面（磁道）*512=8225280字節（B） * 扇區大小（邏輯/物理）：512字節（B）/512字節（B） *輸入/輸出大小（最小/最佳）：512字節（B）/512字節（B） *磁盤標識：0x00079700 */ Disk /dev/sda: 107.4 GB, 107374182400 bytes 255 heads, 63 sectors/track, 13054 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00079700 /*設備 啟動標識 開始位置 結束位置 分區塊的大小 分區ID 系統（分區類型） * /dev/sda1 * 1 64 512000 83 Linux * 分區1不以柱面邊界結束 * /dev/sda2 64 13055 104344576 8e Linux LVM */ Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 13055 104344576 8e Linux LVM Disk /dev/sdb: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_centos6-lv_root: 53.7 GB, 53687091200 bytes 255 heads, 63 sectors/track, 6527 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_centos6-lv_swap: 4194 MB, 4194304000 bytes 255 heads, 63 sectors/track, 509 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_centos6-lv_home: 49.0 GB, 48964304896 bytes 255 heads, 63 sectors/track, 5952 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000
2）.使用-l和-u選項，用扇區編號取代柱面編號顯示所有分區表
Disk /dev/sda: 107.4 GB, 107374182400 bytes 255 heads, 63 sectors/track, 13054 cylinders, total 209715200 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00079700 Device Boot Start End Blocks Id System /dev/sda1 * 2048 1026047 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 1026048 209715199 104344576 8e Linux LVM Disk /dev/sdb: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_centos6-lv_root: 53.7 GB, 53687091200 bytes 255 heads, 63 sectors/track, 6527 cylinders, total 104857600 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_centos6-lv_swap: 4194 MB, 4194304000 bytes 255 heads, 63 sectors/track, 509 cylinders, total 8192000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_centos6-lv_home: 49.0 GB, 48964304896 bytes 255 heads, 63 sectors/track, 5952 cylinders, total 95633408 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000
3）.你們也看到了，我的/dev/sdb還沒有開始使用，下面就用這個硬盤簡單的演示下fdisk主要用到的操作菜單
1.在操作菜單下，創建一個新的分區
[root@CentOS6 桌面]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xe8517189.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended //擴展分區，創建擴展分區會占用一個主分區，並且只有創建擴展分區后才能創建邏輯分區
p primary partition (1-4) //主分區，最多創建4個
e
Partition number (1-4): 1
First cylinder (1-2610, default 1): //起始柱面，默認為1
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): //終止柱面，默認為最后一個數
Using default value 2610
Command (m for help): n
Command action
l logical (5 or over) //邏輯分區
p primary partition (1-4) //主分區
l
First cylinder (1-2610, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +10G //終止柱面不僅可以用柱面數表示，還可以用+[數值][單位]的格式表示
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First cylinder (1307-2610, default 1307):
Using default value 1307
Last cylinder, +cylinders or +size{K,M,G} (1307-2610, default 2610):
Using default value 2610
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe8517189
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 5 Extended
/dev/sdb5 1 1306 10490382 83 Linux
/dev/sdb6 1307 2610 10474348+ 83 Linux
Command (m for help): w //寫入磁盤，保存並退出，否則之前的操作都無效。如果不想寫入磁盤就使用q
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
2.在操作菜單下，刪除 一個分區
[root@CentOS6 桌面]# fdisk /dev/sdb
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe8517189
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 5 Extended
/dev/sdb5 1 1306 10490382 83 Linux
/dev/sdb6 1307 2610 10474348+ 83 Linux
Command (m for help): d
Partition number (1-6): 6 //這里輸入的始分區編號，如果刪除擴展分區，那擴展分區下的邏輯分區也會被刪除
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe8517189
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 5 Extended
/dev/sdb5 1 1306 10490382 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
3.在操作菜單下，修改分區類型
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): t
Partition number (1-5): 5 //操作哪一個分區
Hex code (type L to list codes): L //這里會提示你使用L查看類型列表
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): b
Changed system type of partition 5 to b (W95 FAT32)
Command (m for help): p //可以看到由原來的Linux改成了W95 FAT32
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe8517189
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 5 Extended
/dev/sdb5 1 1306 10490382 b W95 FAT32
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: If you have created or modified any DOS 6.x
partitions, please see the fdisk manual page for additional
information.
Syncing disks.
4）.對正在使用的磁盤，再次進行分區時會出現以下提示
WARNING: Re-reading the partition table failed with error 16: 設備或資源忙. The kernel still uses the old table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8)
注意此時分區並不會立刻生效，可以重啟系統，也可以使用提示的命令partprobe或kpartx。
下面展示完整情況內容
[root@xuexi ~]# fdisk /dev/sdb
歡迎使用 fdisk (util-linux 2.23.2)。
更改將停留在內存中，直到您決定將更改寫入磁盤。
使用寫入命令前請三思。
命令(輸入 m 獲取幫助)：n //新建分區
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p //創建主分區
分區號 (2-4，默認 2)：
起始 扇區 (2099200-4194303，默認為 2099200)：
將使用默認值 2099200
Last 扇區, +扇區 or +size{K,M,G} (2099200-4194303，默認為 4194303)：
將使用默認值 4194303
分區 2 已設置為 Linux 類型，大小設為 1023 MiB
命令(輸入 m 獲取幫助)：w //寫入磁盤
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: 設備或資源忙.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
正在同步磁盤。
[root@xuexi ~]# ls /dev/sdb*
/dev/sdb /dev/sdb1
[root@xuexi ~]# partprobe /dev/sdb //通知操作系統分區表已更改
[root@xuexi ~]# ls /dev/sdb*
/dev/sdb /dev/sdb1 /dev/sdb2
注意：能reboot重啟最好重啟，不行再使用命令更新
注意：其實partprobe是更新分區表，但kpartx其實是更新分區映射（涉及到了鏡像文件，例如.img文件），不過還有partx可以用來更新分區表（-a選項新增，-d選項刪除，-u選項更新（好像不能在刪除時使用））。