swapon

Show swap information

$ swapon

$ sudo swapon /path/to/swapfile

$ sudo swapon -a

$ sudo swapon -L swap_label

$ sudo swapon -U uuid

$ swapon -s

swapon [options] [specialfile...]

swapon enables devices and files for paging and swapping. Swap space can be specified by device path, label (-L), or UUID (-U). The command is typically invoked during system startup to distribute paging activity across multiple storage resources.

-a, --all

Enable all swap devices marked in /etc/fstab

Enable trim/discard operations; policy can be 'once' or 'pages'

Silently skip devices that do not exist

Reinitialize swap space if page size mismatches kernel

Use swap partition with the specified label

Use swap partition with the specified UUID

Set swap priority (-1 to 32767, higher is preferred)

Display swap usage summary (deprecated, use --show)

Display customizable swap area table

Use alternative fstab file

Enable verbose output

Higher priority swap areas are used first. When areas have equal priority, they are used in round-robin fashion. The discard option can improve SSD performance but may cause delays.

swapon is part of the util-linux package. Swap space management has been a core part of Unix-like systems for managing virtual memory.

swapoff(8), mkswap(8), fstab(5), free(1)