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This article introduces the relevant knowledge of "the usage of the Linux basic command swapon". Many people will encounter such a dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Swapon

Enables the swap partition on the specified device, and the device or file used is provided by the dedicated file parameter. It can be "- L label" or "- U UUID" to indicate the label or UUID of a device. Calls to swapon usually occur in the system boot script, making all switching devices available, so paging and swapping activities intersect between multiple devices and files.

The scope of this command: RedHat, RHEL, Ubuntu, CentOS, SUSE, openSUSE, Fedora.

1. Grammar

Swapon-s [- h] [- V]

Swapon [- f] [- p priority] [- v] specialfile...

Swapon-a [- e] [- f] [- v]

2. List of options

Option

Description

-V |-- version

Display version information

-h |-- help

Show help documentation

-v |-- verbose

Display details during execution

-a |-- all

Open all swap partitions. All devices marked "swap" in "/ etc/fstab" are available except those with the "noauto" option. Devices that have been used for exchange will be quietly skipped.

-e |-- ifexists

Skip devices that do not exist

-f |-- fixpgsz

If the page size of the swap space does not match the currently running kernel, reinitialize (exec/sbin/mkswap). Mkswap (2) initializes the entire device without checking for error blocks.

-L label

Start the swap partition of the specified label, which requires access to the / proc/ partition.

-p

Set priority 032767. The larger the number, the higher the priority. Add "pri=value" to the "/ etc/fstab" option field used with "swapon-a".

-s |-- summary

Displays a summary of switching purposes by device, equivalent to "cat / proc/swaps"

-U uuid

Start the swap partition of the specified uuid

3. Description

You should not use swapon on vulnerable files. Swapping NFS may not work. Swapon automatically detects and suspends data rewriting swap space signatures with old software (for example, S1SUSPENDjournal S2SUSPENDmt.). The problem is that if we don't, we will have data corruption the next time we try to unsuspend.

4. Examples

1) start sdb4

[root@localhost ~] # swap / / create a swap partition

Setting up swapspace version 1, size = 16380 KiB

LABEL=wj, UUID=aec14728-0f33-4676-8bef-612ea1bdf985

[root@localhost ~] # swapon / dev/sdb4 / / enable swap partition

[root@localhost ~] # swapon-s / dev/sdb4 / / View information

Filename Type Size Used Priority

/ dev/sdb4 partition 16376 0-1

[root@localhost ~] #

2) start in the form of a label

[root@localhost ~] # blkid-c / dev/null / / find the UUID of the swap partition

Dev/sda1: UUID= "059facc9-c58e-42d0-b8f5-7644c4574888" TYPE= "ext4"

Dev/sda2: UUID= "z3WRza-EIUl-dib9-7CGq-zRYt-DMdL-jT2ld9" TYPE= "LVM2_member"

/ dev/mapper/VolGroup-lv_root: UUID= "9ad51e8e-3700-45a8-a195-531a95ff717d" TYPE= "ext4"

/ dev/mapper/VolGroup-lv_swap: UUID= "2ebcaf57-3c6a-45be-8f34-3326d1fa1762" TYPE= "swap"

[root@localhost ~] # free / / View

Total used free shared buffers cached

Mem: 1659316 1601620 57696 0 261664 1075780

-/ + buffers/cache: 264176 1395140

Swap: 0 0 0

[root@localhost ~] # swapon-U 2ebcaf57-3c6a-45be-8f34-3326d1fa1762 / / start the swap partition

[root@localhost ~] # free / / View

Total used free shared buffers cached

Mem: 1659316 1604132 55184 0 261684 1075780

-/ + buffers/cache: 266668 1392648

Swap: 2940920 0 2940920

[root@localhost ~] #

This is the end of the introduction to "the usage of the Linux basic command swapon". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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