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
       configuration 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 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.

       [EINTEGRITY]       Corrupted  data  was  detected  while  reading  from  the file system to open 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.

Debian                                           March 30, 2020                                        SWAPON(2)