How to check the hard disk size and mount the hard disk in Linux

There are two types of hard disks in Linux: mounted and unmounted (similar to hard disk partitions on Windows (C, D, E drives))

(1) Check the size of the mounted hard disk: df -h

(2) View the detailed hard disk partition information (including the sizes of both mounted and unmounted hard disks): fdisk -l

introduce:

(1) df is used to check the disk usage of the file system

(2) du Check disk space usage

(3) fdisk is used for disk partitioning

Detailed explanation:

1. df

The df command can obtain information such as how much space is occupied on the hard disk and how much space is currently left. It can also display the usage of i-nodes and disk blocks by all file systems.

The meanings of the various options of the df command are as follows:

-a: Displays disk usage of all file systems, including file systems with 0 blocks, such as the /proc file system.
-k: Display in k bytes.
-i: Display i-node information instead of disk blocks.
-t: Displays the disk space usage of each specified type of file system.
-x: Lists the disk space usage of file systems that are not of a specified type (the opposite of the t option).
-T: Display the file system type.

Let's first look at an example of using the df command:

//List the disk space usage of each file system#df
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/hda5 381139 332921 28540 93% /
/dev/hda1 46636 6871 37357 16% /boot
/dev/hda3 10041144 6632528 2898556 70% /home
none 127372 0 127372 0% /dev/shm
/dev/hda2 27474876 24130460 1948772 93% /usr
/dev/hda6 256667 232729 10686 96% /var

The first column is the path name of the device file corresponding to the file system (usually a partition on the hard disk); the second column gives the number of data blocks (1024 bytes) contained in the partition; the third and fourth columns respectively indicate the number of used and available data blocks.

◆Users may find it strange that the sum of the number of blocks in the 3rd and 4th columns is not equal to the number of blocks in the 2nd column. This is because a small amount of space is reserved in each partition by default for use by the system administrator. Even if the normal user space is full, the administrator can still log in and have the workspace needed to solve the problem. The Use% column in the list indicates the percentage of space used by ordinary users. If this number reaches 100%, the partition still has space left for system administrators.

Finally, the Mounted on column indicates the mount point of the file system.

//List the i-node usage of each file system.
#df - - /proc
/dev/hda1 12048 38 12010 1% /boot
none 0 0 0 ia
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/hda5 98392 23919 74473 25% /
none 0 0 0 - /dev/pts
/dev/hda3 1275456 355008 920448 28% /home
none 31843 1 31842 1% /dev/shm
/dev/hda2 3489792 133637 3356155 4% /usr
/dev/hda6 66264 9876 56388 15% /var

//List the file system types.
#df -T
Filesystem Type 1k-blocks Used Available Use% Mounted on
/dev/hda5 ext3 381139 332921 28540 93% /
/dev/hda1 ext3 46636 6871 37357 16% /boot
/dev/hda3 ext3 10041144 6632528 2898556 70% /home
none tmpfs 127372 0 127372 0% /dev/shm
/dev/hda2 ext3 27474876 24130460 1948772 93% /usr
/dev/hda6 ext3 256667 232729 10686 96% /var2

2. du

The original meaning of du in English is "disk usage", which means to display the usage of disk space and count the size of the disk space occupied by the directory (or file). The function of this command is to enter each subdirectory of the specified directory level by level and display the file system data blocks (1024 bytes) occupied by the directory. If no specified directory is given, statistics are taken for the current directory.

The meanings of the various options of the df command are as follows:

-s: For each Names parameter, only the total number of occupied data blocks is given.
-a: Recursively display the number of data blocks occupied by each file in the specified directory and subdirectories. If neither -s nor -a is specified, only the number of disk blocks occupied by each directory in Names and its subdirectories will be displayed.
-b: List disk space usage in bytes (the system defaults to kilobytes).
-k: List disk space usage in units of 1024 bytes.
-c: Add a total at the end (system default setting).
-l: Calculate the size of all files, and for hard link files, calculate multiple times.
-x: Skip directories on different file systems and exclude them from statistics.
-h: Convert the data into 2M or 2G format for easy reading.

The following example illustrates the use of the du command:

// Check the disk space occupied by the /mnt directory#du –abk /mnt
1 /mnt/cdrom
1 /mnt/floppy
3 /mnt

//List the disk space occupied by each directory, but do not list the space occupied by each file in detail#du
3684 ./log
84 ./libnids-1.17/doc
720 ./libnids-1.17/src
32 ./libnids-1.17/samples
1064 ./libnids-1.17
4944 .

The first column in the output listing is the amount of disk space in blocks, and the second column lists the names of the directories that use this space.

◆This can be a long list and sometimes just a total is needed. At this time, you can add the -s option to the du command to get the total number:

#du –s /mnt 
3 /mnt

//List the space occupied by all files and directories (using option a) and calculate the size in bytes (using option b) #du –ab /root/mail
6144 mail/sent-mail
1024 mail/saved-messages
8192 mail

3. fdisk

fdisk can divide disk partitions. Here are the steps to use the Fdisk command to partition the disk:

#fdisk /dev/had //Use /dev/had as the default partition device Command (m for help): m //Select command options Command action

 a toggle a bootable flag
 b edit bsd disklabel
 c toggle the dos compatibility flag
 d delete a partition
 l list known partition types
 m print this menu
 n add a new partition
 o create a new empty DOS partition table
 p print the partition table
 q quit without saving changes
 s creates a new empty Sun disklabel
 t change a partition's system id
 u change display/entry units
 v verify the partition table
 w write table to disk and exit
 x extra functionality (experts only)

The user can type "m" at the prompt to display the description of each parameter of the Fdisk command.

Fdisk has many parameters, but only a few are commonly used.

◆In the Linux partitioning process, the p parameter is generally used to display the hard disk partition table information first, and then the future partitions are determined based on the information. As shown below:

Disk /dev/sda: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
 Device Boot Start End Blocks Id System
/dev/hda1 * 41 522 3871665 83 Linux
/dev/hda2 1 40 321268+ 82 Linux swap

Partition table entries are not in disk order
Command (m for help):

◆If you want to completely change the partition format of the hard disk, you can delete the existing hard disk partitions one by one through the d parameter. After the deletion is complete, you can add a new partition using the n parameter. When you press "n", you can see the following:

Command (m for help): n
Command action
 e extended
 p primary partition (1-4)
 p
 Partiton number(1-4):1
 First cylinder(1-1023):1
 Last cylinder or + size or +sizeK or + sizeM(1-1023):+258M

Here you need to select the type of new partition, whether it is a primary partition or an extended partition; and select p or e. Then set the partition size.

◆It should be noted that if there is an extended partition on the hard disk, you can only add logical partitions, not extended partitions.

◆When adding partitions, the default type is Linux Native. If you want to change some of the partitions to other types, such as Linux Swap or FAT32, you can use the command t to change. When you press "t" to change the partition type, the system will prompt which partition to change and what type to change to (if you want to know the partition types supported by the system, type l), as shown below:

Command (m for help): t
Partition number (1-4): 1
Hex code (type L to list codes): 82
Changed system type of partition 1 to 82 (Linux swap)

After changing the partition type, press "w" to save and exit. If you do not want to save, you can select "q" to exit directly, as shown below:

Command (m for help): w

Through the above operations, you can successfully divide the disk partitions as needed.

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