338 lines
8.2 KiB
HTML
338 lines
8.2 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of FSTAB</TITLE>
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</HEAD><BODY>
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<H1>FSTAB</H1>
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Section: File Formats (5)<BR>Updated: February 2015<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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fstab - static information about the filesystems
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<I>/etc/fstab</I>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The file
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<B>fstab</B>
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contains descriptive information about the filesystems the system can mount.
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<B>fstab</B>
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is only read by programs, and not written; it is the duty of the system
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administrator to properly create and maintain this file. The order of records in
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<B>fstab</B>
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is important because
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<B><A HREF="/cgi-bin/man/man2html?8+fsck">fsck</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8),
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and
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<B><A HREF="/cgi-bin/man/man2html?8+umount">umount</A></B>(8)
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sequentially iterate through
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<B>fstab</B>
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doing their thing.
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<P>
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Each filesystem is described on a separate line.
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Fields on each line are separated by tabs or spaces.
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Lines starting with '#' are comments. Blank lines are ignored.
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<P>
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The following is a typical example of an
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<B>fstab</B>
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entry:
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<P>
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<DL COMPACT><DT id="1"><DD>
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LABEL=t-home2 /home ext4 defaults,auto_da_alloc 0 2
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</DL>
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<P>
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<B>The first field</B>
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(<I>fs_spec</I>).
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<DL COMPACT><DT id="2"><DD>
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This field describes the block special device or
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remote filesystem to be mounted.
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<P>
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For ordinary mounts, it will hold (a link to) a block special
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device node (as created by
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<B><A HREF="/cgi-bin/man/man2html?8+mknod">mknod</A></B>(8))
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for the device to be mounted, like `/dev/cdrom' or `/dev/sdb7'.
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For NFS mounts, this field is <host>:<dir>, e.g., `knuth.aeb.nl:/'.
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For filesystems with no storage, any string can be used, and will show up in
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<B><A HREF="/cgi-bin/man/man2html?1+df">df</A></B>(1)
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output, for example. Typical usage is `proc' for procfs; `mem', `none',
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or `tmpfs' for tmpfs. Other special filesystems, like udev and sysfs,
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are typically not listed in
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<B>fstab</B>.
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<P>
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LABEL=<label> or UUID=<uuid> may be given instead of a device name.
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This is the recommended method, as device names are often a coincidence
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of hardware detection order, and can change when other disks are added or removed.
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For example, `LABEL=Boot' or `UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'.
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(Use a filesystem-specific tool like
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<B><A HREF="/cgi-bin/man/man2html?8+e2label">e2label</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+xfs_admin">xfs_admin</A></B>(8),
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or
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<B><A HREF="/cgi-bin/man/man2html?8+fatlabel">fatlabel</A></B>(8)
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to set LABELs on filesystems).
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<P>
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It's also possible to use PARTUUID= and PARTLABEL=. These partitions identifiers
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are supported for example for GUID Partition Table (GPT).
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<P>
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See
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+blkid">blkid</A></B>(8)
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or
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<B><A HREF="/cgi-bin/man/man2html?8+lsblk">lsblk</A></B>(8)
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for more details about device identifiers.
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<P>
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<P>
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Note that
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8)
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uses UUIDs as strings. The string representation of the UUID should be based on
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lower case characters.
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</DL>
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<P>
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<B>The second field</B>
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(<I>fs_file</I>).
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<DL COMPACT><DT id="3"><DD>
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This field describes the mount point (target) for the filesystem. For swap partitions, this
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field should be specified as `none'. If the name of the mount point
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contains spaces or tabs these can be escaped as `\040' and '\011'
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respectively.
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</DL>
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<P>
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<B>The third field</B>
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(<I>fs_vfstype</I>).
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<DL COMPACT><DT id="4"><DD>
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This field describes the type of the filesystem. Linux supports many
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filesystem types: ext4, xfs, btrfs, f2fs, vfat, ntfs, hfsplus,
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tmpfs, sysfs, proc, iso9660, udf, squashfs, nfs, cifs, and many more.
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For more details, see
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8).
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<P>
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An entry
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<I>swap</I>
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denotes a file or partition to be used
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for swapping, cf.
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<B><A HREF="/cgi-bin/man/man2html?8+swapon">swapon</A></B>(8).
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An entry
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<I>none</I>
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is useful for bind or move mounts.
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<P>
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More than one type may be specified in a comma-separated list.
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<P>
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8)
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and
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<B><A HREF="/cgi-bin/man/man2html?8+umount">umount</A></B>(8)
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support filesystem
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<I>subtypes</I>.
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The subtype is defined by '.subtype' suffix. For
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example 'fuse.sshfs'. It's recommended to use subtype notation rather than add
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any prefix to the first fstab field (for example 'sshfs#example.com' is
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deprecated).
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</DL>
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<P>
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<B>The fourth field</B>
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(<I>fs_mntops</I>).
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<DL COMPACT><DT id="5"><DD>
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This field describes the mount options associated with the filesystem.
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<P>
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It is formatted as a comma-separated list of options.
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It contains at least the type of mount
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(<B>ro</B>
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or
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<B>rw</B>),
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plus any additional options appropriate to the filesystem
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type (including performance-tuning options).
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For details, see
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8)
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or
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<B><A HREF="/cgi-bin/man/man2html?8+swapon">swapon</A></B>(8).
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<P>
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Basic filesystem-independent options are:
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<DL COMPACT>
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<DT id="6"><B>defaults</B>
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<DD>
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use default options: rw, suid, dev, exec, auto, nouser, and async.
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<DT id="7"><B>noauto</B>
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<DD>
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do not mount when "mount -a" is given (e.g., at boot time)
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<DT id="8"><B>user</B>
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<DD>
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allow a user to mount
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<DT id="9"><B>owner</B>
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<DD>
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allow device owner to mount
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<DT id="10"><B>comment</B>
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<DD>
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or
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<B>x-<name></B>
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for use by fstab-maintaining programs
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<DT id="11"><B>nofail</B>
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<DD>
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do not report errors for this device if it does not exist.
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</DL>
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</DL>
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<P>
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<B>The fifth field</B>
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(<I>fs_freq</I>).
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<DL COMPACT><DT id="12"><DD>
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This field is used by
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<B><A HREF="/cgi-bin/man/man2html?8+dump">dump</A></B>(8)
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to determine which filesystems need to be dumped.
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Defaults to zero (don't dump) if not present.
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</DL>
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<P>
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<B>The sixth field</B>
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(<I>fs_passno</I>).
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<DL COMPACT><DT id="13"><DD>
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This field is used by
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<B><A HREF="/cgi-bin/man/man2html?8+fsck">fsck</A></B>(8)
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to determine the order in which filesystem checks are done at
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boot time. The root filesystem should be specified with a
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<I>fs_passno</I>
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of 1. Other filesystems should have a
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<I>fs_passno</I>
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of 2. Filesystems within a drive will be checked sequentially, but
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filesystems on different drives will be checked at the same time to utilize
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parallelism available in the hardware.
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Defaults to zero (don't fsck) if not present.
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<P>
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</DL>
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<A NAME="lbAE"> </A>
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<H2>NOTES</H2>
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The proper way to read records from
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<B>fstab</B>
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is to use the routines
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<B><A HREF="/cgi-bin/man/man2html?3+getmntent">getmntent</A></B>(3)
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or
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<B>libmount</B>.
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<P>
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The keyword
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<B>ignore</B>
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as a filesystem type (3rd field) is no longer supported by the pure
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libmount based mount utility (since util-linux v2.22).
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<P>
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<A NAME="lbAF"> </A>
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<H2>FILES</H2>
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<I>/etc/fstab</I>,
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<I><<A HREF="file:///usr/include/fstab.h">fstab.h</A>></I>
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+getmntent">getmntent</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?5+fs">fs</A></B>(5),
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<B><A HREF="/cgi-bin/man/man2html?8+findmnt">findmnt</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+mount">mount</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+swapon">swapon</A></B>(8)
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<A NAME="lbAH"> </A>
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<H2>HISTORY</H2>
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The ancestor of this
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<B>fstab</B>
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file format appeared in 4.0BSD.
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<A NAME="lbAI"> </A>
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<H2>AVAILABILITY</H2>
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This man page is part of the util-linux package and is available from
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<A HREF="https://www.kernel.org/pub/linux/utils/util-linux/.">https://www.kernel.org/pub/linux/utils/util-linux/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="14"><A HREF="#lbAB">NAME</A><DD>
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<DT id="15"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="16"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="17"><A HREF="#lbAE">NOTES</A><DD>
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<DT id="18"><A HREF="#lbAF">FILES</A><DD>
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<DT id="19"><A HREF="#lbAG">SEE ALSO</A><DD>
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<DT id="20"><A HREF="#lbAH">HISTORY</A><DD>
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<DT id="21"><A HREF="#lbAI">AVAILABILITY</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:03 GMT, March 31, 2021
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</BODY>
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</HTML>
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