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fdisk:Linux 下管理磁盘分区的利器 | Linux 中国

一块硬盘可以被划分成一个或多个逻辑磁盘,我们将其称作分区。我们对硬盘进行的划分信息被储存于建立在扇区 0 的分区表(MBR 或 GPT)中。
Linux 需要至少一个分区来当作根文件系统,所以我们不能在没有分区的情况下安装 Linux 系统。当我们创建一个分区时,我们必须将它格式化为一个适合的文件系统,否则我们就没办法往里面储存文件了。
要在 Linux 中完成分区的相关工作,我们需要一些工具。Linux 下有很多可用的相关工具,我们曾介绍过 Parted 命令[1]。不过,今天我们的主角是 fdisk
人人都喜欢用 fdisk,它是 Linux 下管理磁盘分区的最佳利器之一。它可以操作最大 2TB 的分区。大量 Linux 管理员都喜欢使用这个工具,因为当下 LVM 和 SAN 的原因,并没有多少人会用到 2TB 以上的分区。并且这个工具被世界上许多的基础设施所使用。如果你还是想创建比 2TB 更大的分区,请使用 parted 命令 或 cfdisk 命令。
对磁盘进行分区和创建文件系统是 Linux 管理员的日常。如果你在许多不同的环境中工作,你一定每天都会重复几次这项操作。
Linux 内核是如何理解硬盘的?
作为人类,我们可以很轻松地理解一些事情;但是电脑就不是这样了,它们需要合适的命名才能理解这些。
在 Linux 中,外围设备都位于 /dev 挂载点,内核通过以下的方式理解硬盘:
◈ /dev/hdX[a-z]: IDE 硬盘被命名为 hdX
◈ /dev/sdX[a-z]: SCSI 硬盘被命名为 sdX
◈ /dev/xdX[a-z]: XT 硬盘被命名为 xdX
◈ /dev/vdX[a-z]: 虚拟硬盘被命名为 vdX
◈ /dev/fdN: 软盘被命名为 fdN
◈ /dev/scdN or /dev/srN: CD-ROM 被命名为 /dev/scdN 或 /dev/srN
什么是 fdisk 命令?
fdisk 的意思是 固定磁盘Fixed Disk 或 格式化磁盘Format Disk,它是命令行下允许用户对分区进行查看、创建、调整大小、删除、移动和复制的工具。它支持 MBR、Sun、SGI、BSD 分区表,但是它不支持 GUID 分区表(GPT)。它不是为操作大分区设计的。
fdisk 允许我们在每块硬盘上创建最多四个主分区。它们中的其中一个可以作为扩展分区,并下设多个逻辑分区。1-4 扇区作为主分区被保留,逻辑分区从扇区 5 开始。
如何在 Linux 下安装 fdisk?
fdisk 作为核心组件内置于 Linux 中,所以你不必手动安装它。
如何用 fdisk 列出可用磁盘?
在执行操作之前,我们必须知道的是哪些磁盘被加入了系统。要想列出所有可用的磁盘,请执行下文的命令。这个命令将会列出磁盘名称、分区数量、分区表类型、磁盘识别代号、分区 ID 和分区类型。
  1. $ sudo fdisk -l
  2. Disk /dev/sda: 30 GiB, 32212254720 bytes, 62914560 sectors
  3. Units: sectors of 1 * 512 = 512 bytes
  4. Sector size (logical/physical): 512 bytes / 512 bytes
  5. I/O size (minimum/optimal): 512 bytes / 512 bytes
  6. Disklabel type: dos
  7. Disk identifier: 0xeab59449

  8. Device     Boot    Start      End  Sectors Size Id Type
  9. /dev/sda1  *    20973568 62914559 41940992  20G 83 Linux


  10. Disk /dev/sdb: 10 GiB, 10737418240 bytes, 20971520 sectors
  11. Units: sectors of 1 * 512 = 512 bytes
  12. Sector size (logical/physical): 512 bytes / 512 bytes
  13. I/O size (minimum/optimal): 512 bytes / 512 bytes


  14. Disk /dev/sdc: 10 GiB, 10737418240 bytes, 20971520 sectors
  15. Units: sectors of 1 * 512 = 512 bytes
  16. Sector size (logical/physical): 512 bytes / 512 bytes
  17. I/O size (minimum/optimal): 512 bytes / 512 bytes


  18. Disk /dev/sdd: 10 GiB, 10737418240 bytes, 20971520 sectors
  19. Units: sectors of 1 * 512 = 512 bytes
  20. Sector size (logical/physical): 512 bytes / 512 bytes
  21. I/O size (minimum/optimal): 512 bytes / 512 bytes


  22. Disk /dev/sde: 10 GiB, 10737418240 bytes, 20971520 sectors
  23. Units: sectors of 1 * 512 = 512 bytes
  24. Sector size (logical/physical): 512 bytes / 512 bytes
  25. I/O size (minimum/optimal): 512 bytes / 512 bytes
如何使用 fdisk 列出特定分区信息?
如果你希望查看指定分区的信息,请使用以下命令:
  1. $ sudo fdisk -l /dev/sda
  2. Disk /dev/sda: 30 GiB, 32212254720 bytes, 62914560 sectors
  3. Units: sectors of 1 * 512 = 512 bytes
  4. Sector size (logical/physical): 512 bytes / 512 bytes
  5. I/O size (minimum/optimal): 512 bytes / 512 bytes
  6. Disklabel type: dos
  7. Disk identifier: 0xeab59449

  8. Device     Boot    Start      End  Sectors Size Id Type
  9. /dev/sda1  *    20973568 62914559 41940992  20G 83 Linux
如何列出 fdisk 所有的可用操作?
在 fdisk 中敲击 m,它便会列出所有可用操作:
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.

  5. Device does not contain a recognized partition table.
  6. Created a new DOS disklabel with disk identifier 0xe944b373.

  7. Command (m for help): m

  8. Help:

  9.  DOS (MBR)
  10.   a   toggle a bootable flag
  11.   b   edit nested BSD disklabel
  12.   c   toggle the dos compatibility flag

  13.  Generic
  14.   d   delete a partition
  15.   F   list free unpartitioned space
  16.   l   list known partition types
  17.   n   add a new partition
  18.   p   print the partition table
  19.   t   change a partition type
  20.   v   verify the partition table
  21.   i   print information about a partition

  22.  Misc
  23.   m   print this menu
  24.   u   change display/entry units
  25.   x   extra functionality (experts only)

  26.  Script
  27.   I   load disk layout from sfdisk script file
  28.   O   dump disk layout to sfdisk script file

  29.  Save & Exit
  30.   w   write table to disk and exit
  31.   q   quit without saving changes

  32.  Create a new label
  33.   g   create a new empty GPT partition table
  34.   G   create a new empty SGI (IRIX) partition table
  35.   o   create a new empty DOS partition table
  36.   s   create a new empty Sun partition table
如何使用 fdisk 列出分区类型?
在 fdisk 中敲击 l,它便会列出所有可用分区的类型:
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.

  5. Device does not contain a recognized partition table.
  6. Created a new DOS disklabel with disk identifier 0x9ffd00db.

  7. Command (m for help): l

  8. 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris        
  9. 1  FAT12           27  Hidden NTFS Win 82  Linux swap / So c1  DRDOS/sec (FAT-
  10. 2  XENIX root      39  Plan 9          83  Linux           c4  DRDOS/sec (FAT-
  11. 3  XENIX usr       3c  PartitionMagic  84  OS/2 hidden or  c6  DRDOS/sec (FAT-
  12. 4  FAT16 <32M      40  Venix 80286     85  Linux extended  c7  Syrinx        
  13. 5  Extended        41  PPC PReP Boot   86  NTFS volume set da  Non-FS data    
  14. 6  FAT16           42  SFS             87  NTFS volume set db  CP/M / CTOS / .
  15. 7  HPFS/NTFS/exFAT 4d  QNX4.x          88  Linux plaintext de  Dell Utility  
  16. 8  AIX             4e  QNX4.x 2nd part 8e  Linux LVM       df  BootIt        
  17. 9  AIX bootable    4f  QNX4.x 3rd part 93  Amoeba          e1  DOS access    
  18. a  OS/2 Boot Manag 50  OnTrack DM      94  Amoeba BBT      e3  DOS R/O        
  19. b  W95 FAT32       51  OnTrack DM6 Aux 9f  BSD/OS          e4  SpeedStor      
  20. c  W95 FAT32 (LBA) 52  CP/M            a0  IBM Thinkpad hi ea  Rufus alignment
  21. e  W95 FAT16 (LBA) 53  OnTrack DM6 Aux a5  FreeBSD         eb  BeOS fs        
  22. f  W95 Ext'd (LBA) 54  OnTrackDM6      a6  OpenBSD         ee  GPT            
  23. 10  OPUS            55  EZ-Drive        a7  NeXTSTEP        ef  EFI (FAT-12/16/
  24. 11  Hidden FAT12    56  Golden Bow      a8  Darwin UFS      f0  Linux/PA-RISC b
  25. 12  Compaq diagnost 5c  Priam Edisk     a9  NetBSD          f1  SpeedStor      
  26. 14  Hidden FAT16 <3 61="" ab="" arwin="" boot="" f4="" nbsp="" peedstor="" span="">
  27. 16  Hidden FAT16    63  GNU HURD or Sys af  HFS / HFS+      f2  DOS secondary  
  28. 17  Hidden HPFS/NTF 64  Novell Netware  b7  BSDI fs         fb  VMware VMFS    
  29. 18  AST SmartSleep  65  Novell Netware  b8  BSDI swap       fc  VMware VMKCORE
  30. 1b  Hidden W95 FAT3 70  DiskSecure Mult bb  Boot Wizard hid fd  Linux raid auto
  31. 1c  Hidden W95 FAT3 75  PC/IX           bc  Acronis FAT32 L fe  LANstep        
  32. 1e  Hidden W95 FAT1 80  Old Minix       be  Solaris boot    ff  BBT
如何使用 fdisk 创建一个磁盘分区?
如果你希望新建磁盘分区,请参考下面的步骤。比如我希望在 /dev/sdc 中新建四个分区(三个主分区和一个扩展分区),只需要执行下文的命令。
首先,请在操作 “First sector” 的时候先按下回车,然后在 “Last sector” 中输入你希望创建分区的大小(可以在数字后面加 KB、MB、G 和 TB)。例如,你希望为这个分区扩容 1GB,就应该在 “Last sector” 中输入 +1G。当你创建三个分区之后,fdisk 默认会将分区类型设为扩展分区,如果你希望创建第四个主分区,请输入 p 来替代它的默认值 e
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.


  5. Command (m for help): n
  6. Partition type
  7.   p   primary (0 primary, 0 extended, 4 free)
  8.   e   extended (container for logical partitions)
  9. Select (default p): Enter

  10. Using default response p.
  11. Partition number (1-4, default 1): Enter
  12. First sector (2048-20971519, default 2048): Enter
  13. Last sector, +sectors or +size{K,M,G,T,P} (2048-20971519, default 20971519): +1G

  14. Created a new partition 1 of type 'Linux' and of size 1 GiB.

  15. Command (m for help): p
  16. Disk /dev/sdc: 10 GiB, 10737418240 bytes, 20971520 sectors
  17. Units: sectors of 1 * 512 = 512 bytes
  18. Sector size (logical/physical): 512 bytes / 512 bytes
  19. I/O size (minimum/optimal): 512 bytes / 512 bytes
  20. Disklabel type: dos
  21. Disk identifier: 0x8cc8f9e5

  22. Device     Boot Start     End Sectors Size Id Type
  23. /dev/sdc1        2048 2099199 2097152   1G 83 Linux

  24. Command (m for help): w
  25. The partition table has been altered.
  26. Calling ioctl() to re-read partition table.
  27. Syncing disks.
如何使用 fdisk 创建扩展分区?
请注意,创建扩展分区时,你应该使用剩下的所有空间,以便之后在扩展分区下创建逻辑分区。
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.


  5. Command (m for help): n
  6. Partition type
  7.   p   primary (3 primary, 0 extended, 1 free)
  8.   e   extended (container for logical partitions)
  9. Select (default e): Enter

  10. Using default response e.
  11. Selected partition 4
  12. First sector (6293504-20971519, default 6293504): Enter
  13. Last sector, +sectors or +size{K,M,G,T,P} (6293504-20971519, default 20971519): Enter

  14. Created a new partition 4 of type 'Extended' and of size 7 GiB.

  15. Command (m for help): p
  16. Disk /dev/sdc: 10 GiB, 10737418240 bytes, 20971520 sectors
  17. Units: sectors of 1 * 512 = 512 bytes
  18. Sector size (logical/physical): 512 bytes / 512 bytes
  19. I/O size (minimum/optimal): 512 bytes / 512 bytes
  20. Disklabel type: dos
  21. Disk identifier: 0x8cc8f9e5

  22. Device     Boot   Start      End  Sectors Size Id Type
  23. /dev/sdc1          2048  2099199  2097152   1G 83 Linux
  24. /dev/sdc2       2099200  4196351  2097152   1G 83 Linux
  25. /dev/sdc3       4196352  6293503  2097152   1G 83 Linux
  26. /dev/sdc4       6293504 20971519 14678016   7G  5 Extended

  27. Command (m for help): w
  28. The partition table has been altered.
  29. Calling ioctl() to re-read partition table.
  30. Syncing disks.
如何用 fdisk 查看未分配空间?
上文中,我们总共创建了四个分区(三个主分区和一个扩展分区)。在创建逻辑分区之前,扩展分区的容量将会以未分配空间显示。
使用以下命令来显示磁盘上的未分配空间,下面的示例中显示的是 7GB:
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.


  5. Command (m for help): F
  6. Unpartitioned space /dev/sdc: 7 GiB, 7515144192 bytes, 14678016 sectors
  7. Units: sectors of 1 * 512 = 512 bytes
  8. Sector size (logical/physical): 512 bytes / 512 bytes

  9.  Start      End  Sectors Size
  10. 6293504 20971519 14678016   7G

  11. Command (m for help): q
如何使用 fdisk 创建逻辑分区?
创建扩展分区后,请按照之前的步骤创建逻辑分区。在这里,我创建了位于 /dev/sdc5 的 1GB 逻辑分区。你可以查看分区表值来确认这点。
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.

  5. Command (m for help): n
  6. All primary partitions are in use.
  7. Adding logical partition 5
  8. First sector (6295552-20971519, default 6295552): Enter
  9. Last sector, +sectors or +size{K,M,G,T,P} (6295552-20971519, default 20971519): +1G

  10. Created a new partition 5 of type 'Linux' and of size 1 GiB.

  11. Command (m for help): p
  12. Disk /dev/sdc: 10 GiB, 10737418240 bytes, 20971520 sectors
  13. Units: sectors of 1 * 512 = 512 bytes
  14. Sector size (logical/physical): 512 bytes / 512 bytes
  15. I/O size (minimum/optimal): 512 bytes / 512 bytes
  16. Disklabel type: dos
  17. Disk identifier: 0x8cc8f9e5

  18. Device     Boot   Start      End  Sectors Size Id Type
  19. /dev/sdc1          2048  2099199  2097152   1G 83 Linux
  20. /dev/sdc2       2099200  4196351  2097152   1G 83 Linux
  21. /dev/sdc3       4196352  6293503  2097152   1G 83 Linux
  22. /dev/sdc4       6293504 20971519 14678016   7G  5 Extended
  23. /dev/sdc5       6295552  8392703  2097152   1G 83 Linux

  24. Command (m for help): w
  25. The partition table has been altered.
  26. Calling ioctl() to re-read partition table.
  27. Syncing disks.
如何使用 fdisk 命令删除分区?
如果我们不再使用某个分区,请按照下面的步骤删除它。
请确保你输入了正确的分区号。在这里,我准备删除 /dev/sdc2 分区:
  1. $ sudo fdisk /dev/sdc

  2. Welcome to fdisk (util-linux 2.30.1).
  3. Changes will remain in memory only, until you decide to write them.
  4. Be careful before using the write command.


  5. Command (m for help): d
  6. Partition number (1-5, default 5): 2

  7. Partition 2 has been deleted.

  8. Command (m for help): p
  9. Disk /dev/sdc: 10 GiB, 10737418240 bytes, 20971520 sectors
  10. Units: sectors of 1 * 512 = 512 bytes
  11. Sector size (logical/physical): 512 bytes / 512 bytes
  12. I/O size (minimum/optimal): 512 bytes / 512 bytes
  13. Disklabel type: dos
  14. Disk identifier: 0x8cc8f9e5

  15. Device     Boot   Start      End  Sectors Size Id Type
  16. /dev/sdc1          2048  2099199  2097152   1G 83 Linux
  17. /dev/sdc3       4196352  6293503  2097152   1G 83 Linux
  18. /dev/sdc4       6293504 20971519 14678016   7G  5 Extended
  19. /dev/sdc5       6295552  8392703  2097152   1G 83 Linux

  20. Command (m for help): w
  21. The partition table has been altered.
  22. Calling ioctl() to re-read partition table.
  23. Syncing disks.
如何在 Linux 下格式化分区或建立文件系统?
在计算时,文件系统控制了数据的储存方式,并通过 索引节点Inode Tables 来检索数据。如果没有文件系统,操作系统是无法找到信息储存的位置的。
在此,我准备在 /dev/sdc1 上创建分区。有三种方式创建文件系统:
  1. $ sudo mkfs.ext4 /dev/sdc1
  2. $ sudo mkfs -t ext4 /dev/sdc1
  3. $ sudo mke2fs /dev/sdc1

  4. mke2fs 1.43.5 (04-Aug-2017)
  5. Creating filesystem with 262144 4k blocks and 65536 inodes
  6. Filesystem UUID: c0a99b51-2b61-4f6a-b960-eb60915faab0
  7. Superblock backups stored on blocks:
  8.    32768, 98304, 163840, 229376

  9. Allocating group tables: done                            
  10. Writing inode tables: done                            
  11. Creating journal (8192 blocks): done
  12. Writing superblocks and filesystem accounting information: done
当你在分区上建立文件系统时,以下重要信息会同时被创建:
◈ Filesystem UUID: UUID 代表了通用且独一无二的识别符,UUID 在 Linux 中通常用来识别设备。它 128 位长的数字代表了 32 个十六进制数。
◈ Superblock: 超级块储存了文件系统的元数据。如果某个文件系统的超级块被破坏,我们就无法挂载它了(也就是说无法访问其中的文件了)。
◈ Inode: Inode 是类 Unix 系统中文件系统的数据结构,它储存了所有除名称以外的文件信息和数据。
◈ Journal: 日志式文件系统包含了用来修复电脑意外关机产生下错误信息的日志。
如何在 Linux 中挂载分区?
在你创建完分区和文件系统之后,我们需要挂载它们以便使用。我们需要创建一个挂载点来挂载分区,使用 mkdir 来创建一个挂载点。
  1. $ sudo mkdir -p /mnt/2g-new
如果你希望进行临时挂载,请使用下面的命令。在计算机重启之后,你会丢失这个挂载点。
  1. $ sudo mount /dev/sdc1 /mnt/2g-new
如果你希望永久挂载某个分区,请将分区详情加入 fstab 文件。我们既可以输入设备名称,也可以输入 UUID。
使用设备名称来进行永久挂载:
  1. # vi /etc/fstab

  2. /dev/sdc1 /mnt/2g-new ext4 defaults 0 0
使用 UUID 来进行永久挂载(请使用 blkid 来获取 UUID):
  1. $ sudo blkid
  2. /dev/sdc1: UUID="d17e3c31-e2c9-4f11-809c-94a549bc43b7" TYPE="ext2" PARTUUID="8cc8f9e5-01"
  3. /dev/sda1: UUID="d92fa769-e00f-4fd7-b6ed-ecf7224af7fa" TYPE="ext4" PARTUUID="eab59449-01"
  4. /dev/sdc3: UUID="ca307aa4-0866-49b1-8184-004025789e63" TYPE="ext4" PARTUUID="8cc8f9e5-03"
  5. /dev/sdc5: PARTUUID="8cc8f9e5-05"

  6. # vi /etc/fstab

  7. UUID=d17e3c31-e2c9-4f11-809c-94a549bc43b7 /mnt/2g-new ext4 defaults 0 0
使用 df 命令亦可:
  1. $ df -h
  2. Filesystem      Size  Used Avail Use% Mounted on
  3. udev            969M     0  969M   0% /dev
  4. tmpfs           200M  7.0M  193M   4% /run
  5. /dev/sda1        20G   16G  3.0G  85% /
  6. tmpfs           997M     0  997M   0% /dev/shm
  7. tmpfs           5.0M  4.0K  5.0M   1% /run/lock
  8. tmpfs           997M     0  997M   0% /sys/fs/cgroup
  9. tmpfs           200M   28K  200M   1% /run/user/121
  10. tmpfs           200M   25M  176M  13% /run/user/1000
  11. /dev/sdc1      1008M  1.3M  956M   1% /mnt/2g-new

via: https://www.2daygeek.com/linux-fdisk-command-to-manage-disk-partitions/

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