df、du、fdisk、lsblk區別

1. df(disk free) 命令用於顯示目前在 Linux 系統上的文件系統磁盤使用情況統計。
   文件-h, --human-readable 使用人類可讀的格式(預設值是不加這個選項的)。

# df -h
Filesystem               Size  Used Avail Use% Mounted on
/dev/mapper/centos-root   17G  4.4G   13G  26% /
devtmpfs                 2.0G     0  2.0G   0% /dev
tmpfs                    2.0G     0  2.0G   0% /dev/shm
tmpfs                    2.0G  9.1M  2.0G   1% /run
tmpfs                    2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/sda1               1014M  161M  854M  16% /boot
tmpfs                    394M  4.0K  394M   1% /run/user/42
tmpfs                    394M   32K  394M   1% /run/user/0

2. du(disk usage)命令用於顯示目錄或文件的大小。
   -h或--human-readable 以K，M，G為單位，提高信息的可讀性。
   -X<文件>或--exclude-from=<文件> 在<文件>指定目錄或文件。
   顯示test目錄下面的子目錄的目錄大小和test目錄的總的大小，最下面的1.3M為test目錄的總大小。

# du -h test
608K    test/test6
308K    test/test4
4.0K    test/scf/lib
4.0K    test/scf/service/deploy/product
4.0K    test/scf/service/deploy/info
12K     test/scf/service/deploy
16K     test/scf/service
4.0K    test/scf/doc
4.0K    test/scf/bin
32K     test/scf
8.0K    test/test3
1.3M    test

3. fdisk 是一個創建和維護分區表的程序，它兼容 DOS 類型的分區表、BSD 或者 SUN 類型的磁盤列表。
   -l 列出素所有分區表。

# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes, 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 label type: dos
Disk identifier: 0x00092469

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200    41943039    19921920   8e  Linux LVM
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.

Disk /dev/sdb: 8796.1 GB, 8796093022208 bytes, 17179869184 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 label type: gpt
Disk identifier: E9DB1E69-E857-400F-8653-F45B587FCAB2


#         Start          End    Size  Type            Name
 1         2048  17179867136      8T  unknown         

Disk /dev/mapper/centos-root: 18.2 GB, 18249416704 bytes, 35643392 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 /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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

4. lsblk 列出所有可用塊設備的信息，而且還能顯示他們之間的依賴關系，但是它不會列出RAM盤的信息。
   塊設備有硬盤，閃存盤，cd-ROM等等。

# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk 
├─sda1            8:1    0    1G  0 part /boot
└─sda2            8:2    0   19G  0 part 
  ├─centos-root 253:0    0   17G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0    8T  0 disk 
└─sdb1            8:17   0    8T  0 part 
sr0              11:0    1 1024M  0 rom