signal.7: improve description in NAME section

[thirdparty/man-pages.git] / man2 / mount.2

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.\" Copyright (C) 1993 Rickard E. Faith <faith@cs.unc.edu>
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.\" and Copyright (C) 2002, 2005 Michael Kerrisk <mtk.manpages@gmail.com>
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.\" Modified 1996-11-04 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 2001-10-13 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"	Added note on historical behavior of MS_NOSUID
.\" Modified 2002-05-16 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"	Extensive changes and additions
.\" Modified 2002-05-27 by aeb
.\" Modified 2002-06-11 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"	Enhanced descriptions of MS_MOVE, MS_BIND, and MS_REMOUNT
.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
.\" 2005-05-18, mtk, Added MNT_EXPIRE, plus a few other tidy-ups.
.\"
.TH MOUNT 2 2008-10-02 "Linux" "Linux Programmer's Manual"
.SH NAME
mount, umount, umount2 \- mount and unmount file systems
.SH SYNOPSIS
.nf
.B "#include <sys/mount.h>"
.sp
.BI "int mount(const char *" source ", const char *" target ,
.BI "          const char *" filesystemtype ", unsigned long " mountflags ,
.BI "          const void *" data );
.sp
.BI "int umount(const char *" target );
.sp
.BI "int umount2(const char *" target ", int " flags );
.fi
.SH DESCRIPTION
.\" FIXME . This page could be better structured
.BR mount ()
attaches the file system specified by
.I source
(which is often a device name, but can also be a directory name
or a dummy) to the directory specified by
.IR target .

.BR umount ()
and
.BR umount2 ()
remove the attachment of the (topmost) file system mounted on
.IR target .

Appropriate privilege (Linux: the
.B CAP_SYS_ADMIN
capability) is required to mount and unmount file systems.

Since Linux 2.4 a single file system can be visible at
multiple mount points, and multiple mounts can be stacked
on the same mount point.
.\" Multiple mounts on same mount point: since 2.3.99pre7.

Values for the
.I filesystemtype
argument supported by the kernel are listed in
.I /proc/filesystems
(like "minix", "ext2", "msdos", "proc", "nfs", "iso9660" etc.).
Further types may become available when the appropriate modules
are loaded.

The
.I mountflags
argument may have the magic number 0xC0ED (\fBMS_MGC_VAL\fP)
in the top 16 bits (this was required in kernel versions prior to 2.4, but
is no longer required and ignored if specified),
and various mount flags (as defined in \fI<linux/fs.h>\fP for libc4 and libc5
and in \fI<sys/mount.h>\fP for glibc2) in the low order 16 bits:
.\" FIXME 2.6.15 added flags for "shared sub-tree" functionality:
.\" MS_UNBINDABLE, MS_PRIVATE, MS_SHARED, MS_SLAVE
.\" These need to be documented on this page.
.\" See:
.\" Documentation/filesystems/sharedsubtree.txt
.\"
.\" http://lwn.net/Articles/159077/
.\"
.\" http://myweb.sudhaa.com:2022/~ram/sharedsubtree/paper/sharedsubtree.1.pdf
.\" Shared-Subtree Concept, Implementation, and Applications in Linux
.\" Al Viro viro@ftp.linux.org.uk
.\" Ram Pai linuxram@us.ibm.com
.\"
.\" http://foss.in/2005/slides/sharedsubtree1.pdf
.\" Shared Subtree Concept and Implementation in the Linux Kernel
.\" Ram Pai
.\"
.TP
.BR MS_BIND " (Linux 2.4 onwards)"
.\" since 2.4.0-test9
Perform a bind mount, making a file or a directory subtree visible at
another point within a file system.
Bind mounts may cross file system boundaries and span
.BR chroot (2)
jails.
The
.IR filesystemtype
and
.IR data
arguments are ignored.
Up until Linux 2.6.26,
.I mountflags
was also ignored
.\" with the exception of the "hidden" MS_REC mountflags bit