swapon

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Wat het doet

swapon DEVICE activates a swap partition, LV or file; swapon -a activates all swap lines from /etc/fstab. swapon --show lists active swap spaces with size, use and priority. swapoff moves the pages back to RAM and turns swap off — it needs enough free memory.

Zo schrijf je het

swapon [OPTION]... [DEVICE]...
swapon --show
swapoff [-va] [DEVICE]...

Opties 18

Meest gebruikt

-a, --all: All swap entries in /etc/fstab (not noauto).
--show[=COLUMNS]: List active swap spaces (NAME, TYPE, SIZE, USED, PRIO).
-s, --summary: Old summary format (like /proc/swaps).
-p, --priority N: Priority (-1 … 32767); higher is used first.
-d, --discard[=once|pages]: Use TRIM on SSDs.
-e, --ifexists: Skip devices that do not exist (with -a).
-f, --fixpgsz: Reinitialize when the page size does not match.
-L LABEL: Use the swap space with this label.
-U UUID: Use the swap space with this UUID.
-o, --options OPTS: Options like in fstab (pri=, discard).
-T, --fstab PATH: Use another fstab file.
--output-all: All columns.
--noheadings: No header line.
--raw: Raw output.
--bytes: Sizes in bytes.
-v, --verbose: Verbose.
-h, --help: Show help.
-V, --version: Show the version.

Voorbeelden 10

$ als gewone gebruiker# als root (of met sudo)

1Switch on a swap partition
```
#swapon /dev/vdb2
```
Active until reboot.

2Show active swap

$swapon --show
NAME      TYPE      SIZE USED PRIO
/dev/dm-1 partition   2G   0B   -2
/dev/vdb2 partition   1G   0B   -3

Lower PRIO is used later.

3Switch on everything from fstab
```
#swapon -a
```
Tests your fstab swap lines.
4Turn swap off
```
#swapoff /dev/vdb2
```
Needs enough free RAM.
5Turn all swap off and on (empty it)
```
#swapoff -a && swapon -a
```
Moves swapped pages back to RAM. Check free -h first.
6Use a fast disk first
```
#swapon -p 10 /dev/nvme0n1p3
```
Higher priority = used first.

7Priority in fstab

#grep swap /etc/fstab
UUID=8f1b… none swap defaults,pri=10 0 0

Kept after reboot.

8By UUID or label
```
#swapon -U 8f1b2c3d-…; swapon -L swap2
```
Without the device name.
9Discard on SSD
```
#swapon -d /dev/nvme0n1p3
```
Frees unused blocks on the SSD.
10Check the kernel view
```
$cat /proc/swaps
```
Same data as swapon -s.

Bestanden

/etc/fstab: Swap lines (type swap).
/proc/swaps: Active swap spaces.

Exitcodes

`0`	Done.
`1`	Error.
`2`	Some swap spaces failed (with -a).

`swapon`

Wat het doet

Zo schrijf je het

Opties 18

Voorbeelden 10

1Switch on a swap partition

2Show active swap

3Switch on everything from fstab

4Turn swap off

5Turn all swap off and on (empty it)

6Use a fast disk first

7Priority in fstab

8By UUID or label

9Discard on SSD

10Check the kernel view

Bestanden

Exitcodes

Volledige handleiding

Wat het doet

Zo schrijf je het

Opties 18

Voorbeelden 10

1Switch on a swap partition

2Show active swap

3Switch on everything from fstab

4Turn swap off

5Turn all swap off and on (empty it)

6Use a fast disk first

7Priority in fstab

8By UUID or label

9Discard on SSD

10Check the kernel view

Bestanden

Exitcodes

Verwante commando's

Gebruikt in deze lessen

Gebruikt in deze labs

Volledige handleiding

`swapon`