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SWAPON(2)		  FreeBSD System Calls Manual		     SWAPON(2)

NAME
     swapon, swapoff --	control	devices	for interleaved	paging/swapping

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     swapon(const char *special);

     int
     swapoff(const char	*special);

DESCRIPTION
     The swapon() system call makes the	block device 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 configu-
     ration time.  The size of the swap	area on	special	is calculated at the
     time the device is	first made available for swapping.

     The 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 swapon() and swapoff() can fail if:

     [ENOTDIR]		A component of the path	prefix is not a	directory.

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

     [ENOENT]		The named device does not exist.

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

     [ELOOP]		Too many symbolic links	were encountered in translat-
			ing the	pathname.

     [EPERM]		The caller is not the super-user.

     [EFAULT]		The special argument points outside the	process's
			allocated address space.

     Additionally, swapon() can	fail for the following reasons:

     [EINVAL]		The system has reached the boot-time limit on the num-
			ber of swap devices, vm.nswapdev.

     [ENOTBLK]		The special argument is	not a block device.

     [EBUSY]		The device specified by	special	has already been made
			available for swapping

     [ENXIO]		The major device number	of special is out of range
			(this indicates	no device driver exists	for the	asso-
			ciated hardware).

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

     Lastly, swapoff() can fail	if:

     [EINVAL]		The system is not currently swapping to	special.

     [ENOMEM]		Not enough virtual memory is available to safely dis-
			able paging and	swapping to the	given device.

SEE ALSO
     config(8),	swapon(8), sysctl(8)

HISTORY
     The swapon() system call appeared in 4.0BSD.  The swapoff() system	call
     appeared in FreeBSD 5.0.

FreeBSD	10.1			 June 4, 1993			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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