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swapon(2) [freebsd man page]

SWAPON(2)						      BSD System Calls Manual							 SWAPON(2)

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 poten- tially available devices are known to the system and defined at system configuration time. The size of the swap area on special is calcu- lated 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 translating 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: [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 associated 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 disable 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. BSD
October 4, 2013 BSD

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SWAPON(8)						     Linux Programmer's Manual							 SWAPON(8)

swapon, swapoff - enable/disable devices and files for paging and swapping SYNOPSIS
/sbin/swapon [-h -V] /sbin/swapon -a [-v] [-e] /sbin/swapon [-v] [-p priority] specialfile ... /sbin/swapon [-s] /sbin/swapoff [-h -V] /sbin/swapoff -a /sbin/swapoff specialfile ... DESCRIPTION
Swapon is used to specify devices on which paging and swapping are to take place. Calls to swapon normally occur in the system multi-user initialization file /etc/rc making all swap devices available, so that the paging and swapping activity is interleaved across several devices and files. Normally, the first form is used: -h Provide help -V Display version -s Display swap usage summary by device. Equivalent to "cat /proc/swaps". Not available before Linux 2.1.25. -a All devices marked as ``swap'' swap devices in /etc/fstab are made available. Devices that are already running as swap are silently skipped. -e When -a is used with swapon, -e makes swapon silently skip devices that do not exist. -p priority Specify priority for swapon. This option is only available if swapon was compiled under and is used under a 1.3.2 or later kernel. priority is a value between 0 and 32767. See swapon(2) for a full description of swap priorities. Add pri=value to the option field of /etc/fstab for use with swapon -a. Swapoff disables swapping on the specified devices and files. When the -a flag is given, swapping is disabled on all known swap devices and files (as found in /proc/swaps or /etc/fstab). NOTE
You should not use swapon on a file with holes. Swap over NFS may not work. SEE ALSO
swapon(2), swapoff(2), fstab(5), init(8), mkswap(8), rc(8), mount(8) FILES
/dev/hd?? standard paging devices /dev/sd?? standard (SCSI) paging devices /etc/fstab ascii filesystem description table HISTORY
The swapon command appeared in 4.0BSD. Linux 1.x 25 September 1995 SWAPON(8)
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