mkswap

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Wat het doet

mkswap writes a swap signature (with a UUID and optional label). Then swapon switches it on. For a swap file, the file must exist first, be owned by root with mode 600, and have no holes.

Zo schrijf je het

mkswap [OPTION]... DEVICE [SIZE]

Opties 14

Meest gebruikt

-L, --label LABEL: Set a label.
-U, --uuid UUID: Set the UUID (clear, random, time or a value).
-c, --check: Check for bad blocks first.
-f, --force: Go on even when the device looks in use or too small.
-p, --pagesize SIZE: Page size to use.
-e, --endianness native|little|big: Byte order.
-v, --swapversion 1: Swap version (only 1).
-s, --size SIZE: Size of a swap file to create (newer util-linux).
-F, --file: Create the swap file (with --size; newer util-linux).
--lock[=MODE]: Lock the device.
-q, --quiet: No warnings.
--verbose: More output.
-h, --help: Show help.
-V, --version: Show the version.

Voorbeelden 10

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

1Swap on a partition

#mkswap /dev/vdb2
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=8f1b2c3d-…

Then swapon /dev/vdb2.

2With a label
```
#mkswap -L swap2 /dev/vdb2
```
fstab can use LABEL=swap2.

3Swap on a logical volume

#lvcreate -n lvswap -L 2G rhel
#mkswap /dev/rhel/lvswap

Easy to grow later.

4A swap file

#dd if=/dev/zero of=/swapfile bs=1M count=1024
#chmod 600 /swapfile
#mkswap /swapfile

1 GiB file without holes.

5Create the swap file in one step (newer util-linux)
```
#mkswap -F -s 1G /swapfile
```
Makes the file with the right mode.

6Use it and make it permanent

#swapon /swapfile
#echo '/swapfile none swap defaults 0 0' >> /etc/fstab

Check with swapon --show.

7Get the UUID for fstab
```
#blkid -s UUID -o value /dev/vdb2
```
Use UUID= in fstab, not the device name.
8Change the swap label later
```
#swaplabel -L swap2 /dev/vdb2
```
Without recreating.
9Check for bad blocks first
```
#mkswap -c /dev/vdb2
```
Slower; for old disks.
10Overwrite a device that looks in use
```
#mkswap -f /dev/vdb2
```
Only when you are sure.

Let op

mkswap deletes the old content of the device.
A swap file with mode other than 600 lets users read memory pages: security risk.

Exitcodes

`0`	Done.
`1`	Error.

`mkswap`

Wat het doet

Zo schrijf je het

Opties 14

Voorbeelden 10

1Swap on a partition

2With a label

3Swap on a logical volume

4A swap file

5Create the swap file in one step (newer util-linux)

6Use it and make it permanent

7Get the UUID for fstab

8Change the swap label later

9Check for bad blocks first

10Overwrite a device that looks in use

Let op

Exitcodes

Volledige handleiding

Wat het doet

Zo schrijf je het

Opties 14

Voorbeelden 10

1Swap on a partition

2With a label

3Swap on a logical volume

4A swap file

5Create the swap file in one step (newer util-linux)

6Use it and make it permanent

7Get the UUID for fstab

8Change the swap label later

9Check for bad blocks first

10Overwrite a device that looks in use

Let op

Exitcodes

Verwante commando's

Gebruikt in deze lessen

Gebruikt in deze labs

Volledige handleiding

`mkswap`