SWAPON(2) MachTen Programmer’s Manual SWAPON(2)
NAME 
swapon - add a swap device for interleaved
paging/swapping
SYNOPSIS 
#include <unistd.h>
int 
swapon(const char *special)
DESCRIPTION 
Swapon() makes the block device special available to the
system for allo- 
cation for paging and swapping. The names of potentially
available de- 
vices 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.
RETURN VALUES 
If an error has occurred, a value of -1 is returned and
errno is set to 
indicate the error.
ERRORS 
Swapon() succeeds unless:
[ENOTDIR] A component of the path prefix is not a directory.
[EINVAL] The pathname contains a
character with the high-order bit 
set.
[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.
[ENOTBLK] Special is not a block device.
[EBUSY] The device specified by
special has already been made 
available for swapping
[EINVAL] The device configured
by special was not configured into 
the system as a swap device.
[ENXIO] The major device number
of special is out of range (this 
indicates no device driver exists for the associated hard-
ware).
[EIO] An I/O error occurred while opening the swap device.
[EFAULT] Special points outside
the process’s allocated address 
space.
SEE ALSO 
swapon(8), config(8)
BUGS 
There is no way to stop swapping on a disk so that the pack
may be dis- 
mounted.
This call will be upgraded in future versions of the system.
HISTORY 
The swapon function call appeared in 4.0BSD.
4th Berkeley Distribution June 4, 1993 2