Linux study note _ 9 _ File System Management _ 3 _/etc/fstab file analysis and Disk Quota Application

--/Etc/fstab file Analysis

 

[Preface: in the previous section, partition mounting will expire after restart. To take effect permanently, you need to write it to the/etc/fstab file]

I. Format: Six Components

Physical partition name/volume label mount point file system default settings check Sequence

LABEL = // ext4 defaults 1/0 0/1/2

/Dev/sda1

 

2. Write partition information to/etc/fstab

/Dev/sdb1/web ext3 defaults 1 [if it is a data partition, check] 2 [check the order ratio/back of the Directory]

In this way, the partition is automatically mounted when the system starts and does not need to be manually mounted.

 

Iii. query and set the volume label

E2label/dev/sda1 // query the volume label

E2label/dev/sdb2 apache // set the volume label

In this case, you can write it to the/etc/fstab file: change the first line of/dev/sdb1 to LABEL = apache, which actually works exactly the same.

 

4. added the swap Partition Function for SWAPFILE

[Dd if =/dev/sda of =/dev/sdb disk copy]

[Free-m free to view memory information.-m is displayed in MB and-g is displayed in g]

 

1. mkdir/var/swap

Chmod 700/var/swap // create a directory for storing swap virtual swap space

 

2. dd if =/dev/zero of =/var/swap/file. swp bs = 1024 k count = 10

Explanation: Two pseudo devices in Linux

/Dev/zero: input 0 to the file.

/Dev/null File black hole

Bs: block size: Specifies the file block size.

Count: The file. swp file size, in bs.

Then: dd if =/dev/zero of =/var/swap/file. swp bs = 1024 k count = 10

Indicates that the size of the/var/swap/file. swp file is 10 MB, and the file content is filled with 0.

[Use this command to create a very large file to test the read/write speed of the disk and test whether the disk is full]

3. mkswap/var/swap/file. swp

Create a swap

4. swapon/var/swap/file. swp

Enable the newly created swap space

Swapoff/var/swap/file. swp // close the swap space]

5. Write the swap space to the/etc/swaptab file. The swap space is automatically loaded every time the system starts.

/Var/swap/file. swp swap defaults 0 0

 

-- Disk Quota settings

Case:

/Test directory 777 50 m/user

 

1. Enable the partition Disk Quota Function

Edit the/etc/fstab file and Mark usrquota [user quota] or "User Group quota" on the Mount attribute]

Temporary settings: Run mount-o remount, usrquota/home

 

 

Permanent settings:

1. Edit the/etc/fstab file

/Dev/sda3/home ext4 defaults, usrquota 1 2

2. Commands

Mount-o remount/home

 

2. Create a quota database

Quota-cvuga [quota, quota, quota]

-C create

-V: Show Details

-U creates a detection user quota

-G: create a user group quota for detection.

-A: detects all partitions.

Quota-cvu/test // create user quota only, and accurate to/test Partition

After the first command is executed, two files, aquota. user and aquota. groups, will be created.

[There is also a way to use the touch command [frequently used in old UNIX], but we do not recommend it]

3. Enable the quota Function

Quotaon partition name

Example: quotaon/test

[Disable the quota function: quotaoff partition name]

 

Iv. edit user quota

The edquota user name enters the user quota editing mode.

For example, edquota hellen

Format description: blocks (kb) soft hard limits the size of the user's Space

Inodes soft hard limits the number of files created by the user]

Soft limit: defines the amount of disk space that a user can use. When the user exceeds this limit, the user will receive a warning that the quota is exceeded.

 

Hard limit: a file system error is reported when a user attempts to store a file in a directory that has exceeded the limit.

Edquota-t sets the grace period

 

Grace period: defines the duration for users to use their file systems under soft limits.

[Edquota-g user group name

Edit user group quota]

 

* 5. If multiple users need to copy the user quota

Edquota-p template user copy user 1 copy user 2...

 

[Quota user name to view User quota usage. You can view your disk quota without adding a user name]

[Repquota-a or repquota/test administrator to view quota Information]