From 143635c91f784a91d8a0efca1b2369448240f141 Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Wed, 11 Jan 2012 12:14:29 +0100 Subject: build-sys: move swapon from mount/ to sys-utils/ ... to make it independent on mount stuff. Signed-off-by: Karel Zak --- sys-utils/swapon.8 | 220 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 220 insertions(+) create mode 100644 sys-utils/swapon.8 (limited to 'sys-utils/swapon.8') diff --git a/sys-utils/swapon.8 b/sys-utils/swapon.8 new file mode 100644 index 000000000..ee6a2fcf6 --- /dev/null +++ b/sys-utils/swapon.8 @@ -0,0 +1,220 @@ +.\" Copyright (c) 1980, 1991 Regents of the University of California. +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)swapon.8 6.3 (Berkeley) 3/16/91 +.\" +.\" Sun Dec 27 12:31:30 1992: Modified by faith@cs.unc.edu +.\" Sat Mar 6 20:46:02 1993: Modified by faith@cs.unc.edu +.\" Sat Oct 9 09:35:30 1993: Converted to man format by faith@cs.unc.edu +.\" Sat Nov 27 20:22:42 1993: Updated authorship information, faith@cs.unc.edu +.\" Mon Sep 25 14:12:38 1995: Added -v and -p information +.\" Tue Apr 30 03:32:07 1996: Added some text from A. Koppenhoefer +.\" +.TH SWAPON 8 "September 1995" "util-linux" "System Administration" +.SH NAME +swapon, swapoff \- enable/disable devices and files for paging and swapping +.SH SYNOPSIS +Get info: +.br +.in +5 +.B swapon \-s +.RB [ \-h ] +.RB [ \-V ] +.sp +.in -5 +Enable/disable: +.br +.in +5 +.B swapon +.RB [ \-d ] +.RB [ \-f ] +.RB [ \-p +.IR priority ] +.RB [ \-v ] +.IR specialfile ... +.br +.B swapoff +.RB [ \-v ] +.IR specialfile ... +.sp +.in -5 +Enable/disable all: +.br +.in +5 +.B swapon \-a +.RB [ \-e ] +.RB [ \-f ] +.RB [ \-v ] +.br +.B swapoff \-a +.RB [ \-v ] +.in -5 +.SH DESCRIPTION +.B swapon +is used to specify devices on which paging and swapping are to take place. + +The device or file used is given by the +.I specialfile +parameter. It may be of the form +.BI \-L " label" +or +.BI \-U " uuid" +to indicate a device by label or uuid. + +Calls to +.B swapon +normally occur in the system boot scripts making all swap devices available, so +that the paging and swapping activity is interleaved across several devices and +files. + +.B swapoff +disables swapping on the specified devices and files. +When the +.B \-a +flag is given, swapping is disabled on all known swap devices and files +(as found in +.I /proc/swaps +or +.IR /etc/fstab ). + +.TP +.B "\-a, \-\-all" +All devices marked as ``swap'' in +.I /etc/fstab +are made available, except for those with the ``noauto'' option. +Devices that are already being used as swap are silently skipped. +.TP +.B "\-d, \-\-discard" +Discard freed swap pages before they are reused, if the swap +device supports the discard or trim operation. This may improve +performance on some Solid State Devices, but often it does not. +The +.I /etc/fstab +mount option +.BI discard +may be also used to enable discard flag. +.TP +.B "\-e, \-\-ifexists" +Silently skip devices that do not exist. +The +.I /etc/fstab +mount option +.BI nofail +may be also used to skip non-existing device. + +.TP +.B "\-f, \-\-fixpgsz" +Reinitialize (exec /sbin/mkswap) the swap space if its page size does not +match that of the the current running kernel. +.B mkswap(2) +initializes the whole device and does not check for bad blocks. +.TP +.B \-h, \-\-help +Provide help. +.TP +.B "\-L \fIlabel\fP" +Use the partition that has the specified +.IR label . +(For this, access to +.I /proc/partitions +is needed.) +.TP +.B "\-p, \-\-priority \fIpriority\fP" +Specify the priority of the swap device. +.I priority +is a value between 0 and 32767. Higher numbers indicate higher +priority. See +.BR swapon (2) +for a full description of swap priorities. Add +.BI pri= value +to the option field of +.I /etc/fstab +for use with +.BR "swapon -a" . +.TP +.B "\-s, \-\-summary" +Display swap usage summary by device. Equivalent to "cat /proc/swaps". +Not available before Linux 2.1.25. +.TP +.B "\-U \fIuuid\fP" +Use the partition that has the specified +.IR uuid . +.TP +.B "\-v, \-\-verbose" +Be verbose. +.TP +.B "\-V, \-\-version" +Display version. +.SH NOTES +You should not use +.B swapon +on a file with holes. +Swap over NFS may not work. +.PP +.B swapon +automatically detects and rewrites swap space signature with old software +suspend data (e.g S1SUSPEND, S2SUSPEND, ...). The problem is that if we don't +do it, then we get data corruption the next time an attempt at unsuspending is +made. +.PP +.B swapon +may not work correctly when using a swap file with some versions of btrfs. +This is due to the swap file implementation in the kernel expecting to be able +to write to the file directly, without the assistance of the file system. +Since btrfs is a copy-on-write file system, the file location may not be +static and corruption can result. Btrfs actively disallows the use of files +on its file systems by refusing to map the file. This can be seen in the system +log as "swapon: swapfile has holes." One possible workaround is to map the +file to a loopback device. This will allow the file system to determine the +mapping properly but may come with a performance impact. + +.SH SEE ALSO +.BR swapon (2), +.BR swapoff (2), +.BR fstab (5), +.BR init (8), +.BR mkswap (8), +.BR rc (8), +.BR mount (8) +.SH FILES +.br +.I /dev/sd?? +standard paging devices +.br +.I /etc/fstab +ascii filesystem description table +.SH HISTORY +The +.B swapon +command appeared in 4.0BSD. +.SH AVAILABILITY +The swapon command is part of the util-linux package and is available from +ftp://ftp.kernel.org/pub/linux/utils/util-linux/. -- cgit v1.2.3-55-g7522