swapon (2)

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(The comments found at the beginning of the groff file "man2/swapon.2freebsd".)

NAME

swapon , swapoff - control devices for interleaved paging/swapping

LIBRARY

Lb libc

SYNOPSIS

In unistd.h Ft int Fn swapon const char *special Ft int Fn swapoff const char *special

DESCRIPTION

The Fn swapon system call makes the block device Fa special available to the system for allocation for paging and swapping. The names of potentially available devices are known to the system and defined at system configuration time. The size of the swap area on Fa special is calculated at the time the device is first made available for swapping.

The Fn swapoff system call disables paging and swapping on the given device. All associated swap metadata are deallocated, and the device is made available for other purposes.

RETURN VALUES

If an error has occurred, a value of -1 is returned and errno is set to indicate the error.

ERRORS

Both Fn swapon and Fn swapoff can fail if:

Bq Er ENOTDIR

A component of the path prefix is not a directory.

Bq Er ENAMETOOLONG

A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

Bq Er ENOENT

The named device does not exist.

Bq Er EACCES

Search permission is denied for a component of the path prefix.

Bq Er ELOOP

Too many symbolic links were encountered in translating the pathname.

Bq Er EPERM

The caller is not the super-user.

Bq Er EFAULT

The Fa special argument points outside the process's allocated address space.

Additionally, Fn swapon can fail for the following reasons:

Bq Er ENOTBLK

The Fa special argument is not a block device.

Bq Er EBUSY

The device specified by Fa special has already been made available for swapping

Bq Er ENXIO

The major device number of Fa special is out of range (this indicates no device driver exists for the associated hardware).

Bq Er EIO

An I/O error occurred while opening the swap device.

Lastly, Fn swapoff can fail if:

Bq Er EINVAL

The system is not currently swapping to Fa special .

Bq Er ENOMEM

Not enough virtual memory is available to safely disable paging and swapping to the given device.

SEE ALSO

config(8), swapon(8), sysctl(8)

HISTORY

The Fn swapon system call appeared in BSD 4.0 The Fn swapoff system call appeared in Fx 5.0 .