mirror of https://github.com/vitalif/e2fsprogs
397 lines
10 KiB
Groff
397 lines
10 KiB
Groff
.\" Revision 1.0 93/06/3 23:00 chk
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.\" Initial revision
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.\"
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.\"
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.TH TUNE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
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.SH NAME
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tune2fs \- adjust tunable filesystem parameters on second extended filesystems
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.SH SYNOPSIS
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.B tune2fs
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[
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.B \-l
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]
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[
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.B \-c
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.I max-mount-counts
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]
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[
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.B \-e
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.I errors-behavior
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]
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[
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.B \-f
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]
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[
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.B \-i
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.I interval-between-checks
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]
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[
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.B \-j
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]
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[
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.B \-J
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.I journal-options
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]
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[
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.B \-m
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.I reserved-blocks-percentage
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]
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[
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.B \-r
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.I reserved-blocks-count
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]
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[
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.B \-s
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.I sparse-super-flag
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]
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[
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.B \-u
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.I user
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]
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[
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.B \-g
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.I group
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]
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[
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.B \-C
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.I mount-count
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]
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[
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.B \-L
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.I volume-name
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]
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[
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.B \-M
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.I last-mounted-directory
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]
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[
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.B \-O
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.RI [^] feature [,...]
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]
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[
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.B \-T
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.I time-last-checked
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]
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[
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.B \-U
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.I UUID
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]
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device
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.SH DESCRIPTION
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.BI tune2fs
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adjusts tunable filesystem parameters on a Linux second extended filesystem.
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.SH OPTIONS
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.TP
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.BI \-c " max-mount-counts"
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Adjust the maximal mounts count between two filesystem checks. If
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.I max-mount-counts
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is 0 then the number of times the filesystem is mounted will be disregarded
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by
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.BR e2fsck (8)
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and the kernel.
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.sp
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Staggering the mount-counts at which filesystems are forcibly
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checked will avoid all filesystems being checked at one time
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when using journaled filesystems.
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.sp
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You should strongly consider the consequences of disabling
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mount-count-dependent checking entirely. Bad disk drives, cables,
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memory, and kernel bugs could all corrupt a filesystem without
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marking the filesystem dirty or in error. If you are using
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journaling on your filesystem, your filesystem will
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.B never
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be marked dirty, so it will not normally be checked. A
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filesystem error detected by the kernel will still force
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an fsck on the next reboot, but it may already be too late
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to prevent data loss at that point.
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.sp
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See also the
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.B \-i
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option for time-dependent checking.
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.TP
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.BI \-C " mount-count"
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Set the number of times the filesystem has been mounted.
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Can be used in conjunction with -c to force an fsck on
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the filesystem at the next reboot.
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.TP
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.BI \-e " error-behavior"
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Change the behavior of the kernel code when errors are detected.
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In all cases, a filesystem error will cause
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.BR e2fsck (8)
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to check the filesystem on the next boot.
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.I error-behavior
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can be one of the following:
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.RS 1.2i
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.TP 1.2i
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.B continue
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Continue normal execution.
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.TP
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.B remount-ro
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Remount filesystem read-only.
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.TP
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.B panic
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Cause a kernel panic.
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.RE
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.TP
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.B \-f
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Force the tune2fs operation to complete even in the face of errors. This
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option is useful when removing the
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.B has_journal
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filesystem feature from a filesystem which has
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an external journal (or is corrupted
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such that it appears to have an external journal), but that
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external journal is not available.
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.sp
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.B WARNING:
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Removing an external journal from a filesystem which was not cleanly unmounted
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without first replaying the external journal can result in
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severe data loss and filesystem corruption.
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.TP
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.BI \-g " group"
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Set the group which can use reserved filesystem blocks.
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The
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.I group
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parameter can be a numerical gid or a group name. If a group name is given,
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it is converted to a numerical gid before it is stored in the superblock.
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.TP
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.B \-i " \fIinterval-between-checks\fR[\fBd\fR|\fBm\fR|\fBw\fR]"
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Adjust the maximal time between two filesystem checks.
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No postfix or
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.B d
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result in days,
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.B m
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in months, and
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.B w
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in weeks. A value of zero will disable the time-dependent checking.
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.sp
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It is strongly recommended that either
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.B \-c
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(mount-count-dependent) or
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.B \-i
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(time-dependent) checking be enabled to force periodic full
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.BR e2fsck (8)
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checking of the filesystem. Failure to do so may lead to filesystem
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corruption due to bad disks, cables, memory, or kernel bugs to go
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unnoticed until they cause data loss or corruption.
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.TP
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.B \-j
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Add an ext3 journal to the filesystem. If the
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.B \-J
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option is not specified, the default journal parameters will be used to create
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an appropriately sized journal (given the size of the filesystem)
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stored within the filesystem. Note that you must be using a kernel
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which has ext3 support in order to actually make use of the journal.
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.TP
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.BR \-J " journal-options"
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Override the default ext3 journal parameters. Journal options are comma
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separated, and may take an argument using the equals ('=') sign.
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The following journal options are supported:
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.RS 1.2i
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.TP
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.BI size= journal-size
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Create a journal stored in the filesystem of size
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.I journal-size
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megabytes. The size of the journal must be at least 1024 filesystem blocks
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(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
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and may be no more than 102,400 filesystem blocks.
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There must be enough free space in the filesystem to create a journal of
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that size.
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@JDEV@.TP
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@JDEV@.BI device= external-journal
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@JDEV@Attach the filesystem to the journal block device located on
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@JDEV@.IR external-journal .
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@JDEV@The external
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@JDEV@journal must have been already created using the command
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@JDEV@.IP
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@JDEV@.B mke2fs -O journal_dev
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@JDEV@.I external-journal
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@JDEV@.IP
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@JDEV@Note that
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@JDEV@.I external-journal
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@JDEV@must be formatted with the same block
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@JDEV@size as filesystems which will be using it.
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@JDEV@.IP
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@JDEV@Instead of specifying a device name directly,
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@JDEV@.I external-journal
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@JDEV@can also be specified by either
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@JDEV@.BI LABEL= label
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@JDEV@or
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@JDEV@.BI UUID= UUID
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@JDEV@to locate the external journal by either the volume label or UUID
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@JDEV@stored in the ext2 superblock at the start of the journal. Use
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@JDEV@.BR dumpe2fs (8)
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@JDEV@to display a journal device's volume label and UUID. See also the
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@JDEV@.B -L
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@JDEV@option of
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@JDEV@.BR tune2fs (8).
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.RE
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@JDEV@.IP
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@JDEV@Only one of the
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@JDEV@.BR size " or " device
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@JDEV@options can be given for a filesystem.
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.TP
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.B \-l
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List the contents of the filesystem superblock.
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.TP
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.BI \-L " volume-label"
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Set the volume label of the filesystem.
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Ext2 filesystem labels can be at most 16 characters long; if
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.I volume-label
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is longer than 16 characters,
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.B tune2fs
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will truncate it and print a warning. The volume label can be used
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by
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.BR mount (8),
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.BR fsck (8),
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and
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.BR /etc/fstab (5)
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(and possibly others) by specifying
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.BI LABEL= volume_label
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instead of a block special device name like
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.BR /dev/hda5 .
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.TP
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.BI \-m " reserved-blocks-percentage"
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Set the percentage of reserved filesystem blocks.
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.TP
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.BI \-M " last-mounted-directory"
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Set the last-mounted directory for the filesystem.
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.TP
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.BR \-O " [^]\fIfeature\fR[,...]"
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Set or clear the indicated filesystem features (options) in the filesystem.
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More than one filesystem feature can be cleared or set by separating
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features with commas. Filesystem features prefixed with a
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caret character ('^') will be cleared in the filesystem's superblock;
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filesystem features without a prefix character or prefixed with a plus
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character ('+') will be added to the filesystem.
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.IP
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The following filesystem features can be set or cleared using
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.BR tune2fs :
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.RS 1.2i
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.TP
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.B sparse_super
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Limit the number of backup superblocks to save space on large filesystems.
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.TP
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.B filetype
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Store file type information in directory entries.
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.TP
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.B has_journal
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Create an ext3 journal (as if using the
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.B \-j
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option).
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.RE
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.IP
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After setting or clearing
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.B sparse_super
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and
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.B filetype
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filesystem features,
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.BR e2fsck (8)
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must be run on the filesystem to return the filesystem to a consistent state.
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.B Tune2fs
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will print a message requesting that the system administrator run
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.BR e2fsck (8)
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if necessary.
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.IP
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.B Warning:
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Linux kernels before 2.0.39 and many 2.1 series kernels do not support
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the filesystems that use any of these features.
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Enabling certain filesystem features may prevent the filesystem from
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being mounted by kernels which do not support those features.
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.TP
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.BI \-r " reserved-blocks-count"
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Set the number of reserved filesystem blocks.
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.TP
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.BR \-s " [" 0 | 1 ]
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Turn the sparse super feature off or on. Turning this feature on
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saves space on really big filesystems. This is the same as using the
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.B "\-O sparse_super"
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option.
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.IP
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.B Warning:
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Linux kernels before 2.0.39 do not support this feature. Neither do
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all Linux 2.1 kernels; please don't use this unless you know what you're
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doing! You need to run
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.BR e2fsck (8)
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on the filesystem after changing this feature in order to have a valid
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filesystem.
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.TP
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.BI \-T " time-last-checked"
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Set the time the filesystem was last checked using
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.BR e2fsck .
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This can be useful in scripts which use a Logical Volume Manager to make
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a consistent snapshot of a filesystem, and then check the filesystem
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during off hours to make sure it hasn't been corrupted due to
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hardware problems, etc. If the filesystem was clean, then this option can
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be used to set the last checked time on the original filesystem. The format
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of
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.I time-last-checked
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is the international date format, with an optional time specifier, i.e.
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YYYYMMDD[[HHMM]SS]. The keyword
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.B now
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is also accepted, in which case the last checked time will be set to the
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current time.
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.TP
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.BI \-u " user"
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Set the user who can use the reserved filesystem blocks.
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.I user
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can be a numerical uid or a user name. If a user name is given, it
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is converted to a numerical uid before it is stored in the superblock.
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.TP
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.BI \-U " UUID"
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Set the universally unique identifier (UUID) of the filesystem to
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.IR UUID .
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The format of the UUID is a series of hex digits separated by hypthens,
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like this:
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"c1b9d5a2-f162-11cf-9ece-0020afc76f16".
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The
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.I UUID
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parameter may also be one of the following:
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.RS 1.2i
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.TP
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.I clear
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clear the filesystem UUID
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.TP
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.I random
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generate a new randomly-generated UUID
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.TP
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.I time
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generate a new time-based UUID
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.RE
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.IP
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The UUID may be used by
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.BR mount (8),
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.BR fsck (8),
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and
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.BR /etc/fstab (5)
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(and possibly others) by specifying
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.BI UUID= uuid
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instead of a block special device name like
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.BR /dev/hda1 .
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.IP
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See
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.BR uuidgen (8)
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for more information.
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If the system does not have a good random number generator such as
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.I /dev/random
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or
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.IR /dev/urandom ,
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.B tune2fs
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will automatically use a time-based UUID instead of a randomly-generated UUID.
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.SH BUGS
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We haven't found any bugs yet. That doesn't mean there aren't any...
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.SH AUTHOR
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.B tune2fs
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was written by Remy Card <Remy.Card@linux.org>.
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.B tune2fs
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uses the ext2fs library written by Theodore Ts'o <tytso@mit.edu>.
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This manual page was written by Christian Kuhtz <chk@data-hh.Hanse.DE>.
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Time-dependent checking was added by Uwe Ohse <uwe@tirka.gun.de>.
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.SH AVAILABILITY
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.B tune2fs
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is part of the e2fsprogs package and is available from
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http://e2fsprogs.sourceforge.net.
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.SH SEE ALSO
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.BR dumpe2fs (8),
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.BR e2fsck (8),
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.BR mke2fs (8)
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