Linux-----Disk Management

DF

DF Command:

View the file system space usage information.

Use this command to see how much space the hard disk has been using, how much space is left, and to view all mounted devices (file systems) and mount points on the current disk.

The results are as follows: ① file system ② Total disk capacity ③ used capacity ④ remaining capacity ⑤ used percent ⑥ mount point

Note: The temporary file system with TMPFS is reset after the reboot.

If DF does not have any options, the default is to list all of the system's (non-special in-memory file systems and Swaps) in 1 Kbytes capacity!

Options:

-I: Show details for Inode-H: Display information in the appropriate units-K: Display information in units-M: Display information in meters-T: View File system types

Example:

DF: View system disk device, default is KB

Df-h: View system disk devices, display them in the appropriate units

Du

Du command:

Used to view the overall space usage of a directory

The du command also looks at the space used, but unlike the DF command, the Linux du command is a view of the space used by the file and directory disks, and the du command actually searches the file system for all the file data.

Options:

-H: Display information in appropriate units-s: Displays only the sum of all file sizes in the specified directory-K: Displays information in kilobytes-M: Displays information in megabytes

Example:

Du-sh: Displays the sum of all the file sizes in the specified directory in the appropriate units

Free command:

See how memory space is used

Options:

-M: in MB-G: in gigabytes

Example:

Free-m: View the usage of memory space in megabytes

Free-g: View the usage of memory space in gigabytes

parted command:

Parted is a high-level partition Operation command, which operates in real time and is used with care. In CentOS 7 You can update the hard drive with the Partprobe command, CentOS 6 is not available.

Usage:

parted [options] ... [Device [command [parameters] ...]        ...] Parted/dev/device Mklabel GPT |  MSDOS: Change disk type to GPT or MBR parted/dev/device print: Display disk partition information Parted/dev/device Mkpart Primary 1 1000: Create partition 1 is the partition number; 1000 is the partition size (default is m) parted/dev/device RM 1: Delete the first partition parted-l: List all device information

FDISK:MRB Partitioning Tool

Fdisk is the Linux MRB partition table Manipulation tool, Gdisk is the GPT Partition Table Operation tool, the usage and Fdisk basically consistent.

FDISK/DEV/SDX: Managing SdX disks, modifying partitions on specified hard disks

FDISK subcommand:

M: Help o: Create MSDOS partition label N: Create new partition D: Delete partition P: View current Partition Table A: Add/Cancel Boot tag T: Convert partition type ID l/l: Show partition type ID table

Example:

FDISK-L: Lists partition information for all block devices

Fdisk-l/DEV/SDX: View partition information for a specified block device

Cat/proc/partitions to see if the kernel has identified a new partition:

Note: If there is only fdisk-l, the system will list the partitions of the device that can be searched in the whole system.

Four, disk format

MKFS command:

Creating a file system

MKE2FS is a dedicated management tool for the EXT series file system

To view supported file systems: Cat/proc/filesystems

Configuration file:/etc/mke2fs.conf for setting default features and individual file system specific features

Create ext File System

Options:

-T: Specifies the file system type {ext2 | ext3 | ext4}-J: equivalent to-t ext3 mkfs.ext3 = mkfs-t ext3 = mke2fs-j = mke2fs-t ext3- L Label: Specify the Volume label,-b{1024|2028|4096}: Specify the block Size-I #: Create an inode for each number of bytes in the data space; This size should not be less than the size of the block-N #: How many Inod are created directly in the specified partition E-i N: Specify Inode size-M #: Reserve Space for administrators as a percentage of total space, default is 5%-O feature[,...]: Enable the specified attribute (only the following attribute is turned on)-O ^feature Disable the specified attribute

TUNE2FS command:

Modify the file system information to reset the value of the EXT series file system adjustable parameters

-L: View the specified file system super block information; Super block-l ' label ': Modify the volume label (EXT) mkfs-l ' label ' or mke2fs-l ' label ' to set the volume label when created E2la bel/dev/sd# View Volume label e2label/dev/sd# ' LABEL ' Rename volume label-M #: Fixed percentage of space reserved for administrators-j: Upgrade ext2 to Ext3-o: File System Properties Start Use or disable, –O ^has_journal-o: Adjust the default mount option of the file system, –O ^acl (default on ACL 6 is not turned on by default)-U uuid: Modify the UUID number

Example: Tune2fs-o acl/dev/sdb2 to turn on/dev/sdb2 ACL function

dumpe2fs/dev/sda# viewing file System Information: Superblock Information and block group information

-H: View Super block, do not show block group but only show Superblock and tune2fs-l consistent

Tip: The super block is the file system built-in, specifying the file system type

Block Group 0 has super block, after Odd group has backup, can be used to repair

File System Detection:

Fsck:

Used to check and maintain inconsistent file systems

Options:

-T: File type device-F: Force detect-A: Automatic fix error if check errors-r: Interactive fix error

Example:

Fsck-y: Check to fix each file

Note: If you do not add-f option, because this file system has not been the problem, the check is very fast! If you add the-f mandatory Check, an item is displayed.

E2fsck:ext Series file system-specific detection and repair tools

-Y: Auto answer for YES-F: Force detection

Disk Mounts and Uninstalls:

Mount

Mount Command:

Display the currently mounted device by viewing the/etc/fstab file

Usage:

Mount [Options]-o [option]-t file type device mount directory device: (1) device file: For example/DEV/SR0,/DEV/SDB1 (2) Volume Label:-L ' volume label Name ' (3) UUID :-U ' UUID ' (4) pseudo file system name: PROC,SYSFS mount Directory: (1) must exist beforehand, try to use empty directory

Options:

   -T&NBSP: Specifies the file system type to mount the device    -r :readonly, read-only Mount    -w  : Read-write Mount    -n : Do not update/etc/mtab after mount, cause mount and DF command not to query to mount information, but can view/proc/mounts   -a &NBSP: Read/etc/fstab  mount the file system that is not currently mounted, the mounted file system will not be re-mounted, nor will it update the Mount option    -l : Specify the device to mount by the volume label name     -U&NBSP: Specifies the device    -b,--bind&nbsp to be mounted with the UUID;: Binds the directory to another directory (equivalent to a soft link)    -o  [OPTIONS]&NBSP: (option to mount file system), multiple options separated by commas         async  (default )   Asynchronous Mode   sync  sync mode, sync now                  atime  (default)   file is accessed when the update atime  noatime  file is accessed and not updated Atime                 diratime  (default)   When the directory is accessed, the update atime nodiratime  directory is accessed without updating atime                 auto  (default)   MOUNT -A auto Mount after writing/etc/fstab                  noauto  after writing/etc/fstab, Not automatically mounted by Mount -a                  exec  (default)   files with RX permission in this directory can be executed                  noexec  all files under this directory will not be executed for all users, including Root,                  dev  (default)   device files can be used in this directory                  nodev  Device files in this directory cannot be used                  suid  (default)   indicates that Suid,sgid permissions in this directory are in effect                  nosuid  indicates that suid,sgid permissions in this directory do not take effect                  remount,xxx   without uninstalling, you can update the Mount options directly                  rw  (default)                   ro                  nouser (default)   write/etc/fstab items cannot be loaded/unloaded by normal users                  user  Write/etc/ Fstab project allows normal users to mount/uninstall                  acl  (Centos7 default)   files in this directory can set ACL permissions                  noacl  (CENTOS6 and previous  default)   files in this directory can not set ACL permissions                 loop  when mounting a loop device, such as an ISO, specify the                  defaults rw, suid,  dev, exec, auto, nouser, async,atime,diratime,acl (CENTOS7)

Example:

Cat/proc/mounts: View all mounted devices tracked by the kernel

Note: After the file is mounted successfully,/etc/mtab is not updated after mounting, resulting in mount and DF commands not being able to query the mount information, but can be viewed with df-a.

/etc/fstab each row defines a file system to mount.

Tool DD:

dd if=file  of=file  bs=n  count=n    if=file  : reading data from a file     of=file : Output to a file     bs=size : block  Size, specifying the block size (ibs=obs)     ibs=size : Reads a size byte    obs=size  at a time : Write one size byte    cbs=size&nbsp at a time;: One conversion size byte    skip=blocks  : Ignores blocks of IBS-sized blocks from the beginning     seek=blocks : Ignores blocks of blocks obs size from the beginning     count  :  Copy the number of bs    conv=onversion... : Convert file      transform parameters with specified parameters:             ascii : Convert EBCDIC code to ascii             EBCDIC&NBSP: convert ASCII to ebcdic             LCASE&NBSP: Convert uppercase characters to lowercase              UCASE&NBSP: Convert lowercase to uppercase             nocreat &NBSP: Do not create output file             noerror : Do not stop on error             NOTRUNC&NBSP: Not truncated output file               SYNC&NBSP: Fills the input block to the IBS bytes, the insufficient part is filled with the empty (NUL) character

Linux-----Disk Management