.\" Copyright 1998 Andries E. Brouwer (aeb@cwi.nl)
.\"
.\" May be distributed under the GNU General Public License
-.\" Rewritten for 2.1.117, aeb, 981010.
.\"
.TH MKSWAP 8 "March 2009" "util-linux" "System Administration"
.SH NAME
mkswap \- set up a Linux swap area
.SH SYNOPSIS
.B mkswap
-.RI [ options ]
+[options]
.I device
.RI [ size ]
.SH DESCRIPTION
(It specifies the desired size of the swap area in 1024-byte blocks.
.B mkswap
will use the entire partition or file if it is omitted.
-Specifying it is unwise -- a typo may destroy your disk.)
+Specifying it is unwise \(en a typo may destroy your disk.)
After creating the swap area, you need the
.B swapon
command to start using it. Usually swap areas are listed in
.I /etc/fstab
so that they can be taken into use at boot time by a
-.B swapon -a
+.B swapon \-a
command in some boot script.
.SH WARNING
However,
.B mkswap
refuses to erase the first block on a device with a disk
-label (SUN, BSD, ...).
+label (SUN, BSD, \&...\&).
.SH OPTIONS
.TP
the kernel version.
The maximum number of the pages that is possible to address by swap area header
-is 4294967295 (UINT_MAX). The remaining space on the swap device is ignored.
+is 4294967295 (32-bit unsigned int). The remaining space on the swap device is ignored.
Presently, Linux allows 32 swap areas.
The areas in use can be seen in the file
refuses areas smaller than 10 pages.
If you don't know the page size that your machine uses, you may be
-able to look it up with "cat /proc/cpuinfo" (or you may not --
+able to look it up with "cat /proc/cpuinfo" (or you may not \(en
the contents of this file depend on architecture and kernel version).
To set up a swap file, it is necessary to create that file before
initializing it with
.BR mkswap ,
-e.g. using a command like
+e.g.\& using a command like
.nf
.RS
-# fallocate --length 8GiB swapfile
+# dd if=/dev/zero of=swapfile bs=1MiB count=$((8*1024))
.RE
.fi
-Note that a swap file must not contain any holes (so, using
-.BR cp (1)
-to create the file is not acceptable).
+to create 8GiB swapfile.
+
+Please read notes from
+.BR swapon (8)
+about
+.B the swap file use restrictions
+(holes, preallocation and copy-on-write issues).
.SH ENVIRONMENT
-.IP LIBBLKID_DEBUG=0xffff
-enables debug output.
+.IP LIBBLKID_DEBUG=all
+enables libblkid debug output.
.SH "SEE ALSO"
.BR fdisk (8),
.BR swapon (8)
.SH AVAILABILITY
The mkswap command is part of the util-linux package and is available from
-ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
+https://www.kernel.org/pub/linux/utils/util-linux/.