swap – establish a swap file


swap file


Swap establishes a file for the system to swap on. If file is an existing file, it is used for system swap. If it does not exist, a new file is created. If file is a directory, a unique file is created in that directory on which to swap. The environment variable swap is set to the full name of the resulting file. The number of blocks available in the file or device must be at least the number of swap blocks configured at system boot time.

If a swap channel has already been set and no blocks are currently valid in the file the old file will be closed and then replaced. If any blocks are valid on the device an error is returned instead.




Swapping to a file served by a local user-level process will lead to deadlock if the process isn’t made non-swappable (see the noswap ctl-message in proc(3)).


swap(3), proc(3)