.SH SYNOPSIS
.B tune2fs
[
-.B -l
+.B \-l
]
[
-.B -c
+.B \-c
.I max-mount-counts
]
[
-.B -e
+.B \-e
.I errors-behavior
]
[
-.B -i
+.B \-i
.I interval-between-checks
]
[
-.B -m
+.B \-j
+]
+[
+.B \-J
+.I journal-options
+]
+[
+.B \-m
.I reserved-blocks-percentage
]
[
-.B -r
+.B \-r
.I reserved-blocks-count
]
[
-.B -s sparse-super-flag
+.B \-s
+.I sparse-super-flag
]
[
-.B -u
+.B \-u
.I user
]
[
-.B -g
+.B \-g
.I group
]
[
-.B -C
+.B \-C
.I mount-count
]
[
-.B -L
+.B \-L
.I volume-name
]
[
-.B -M
+.B \-M
.I last-mounted-directory
]
[
-.B -U
+.B \-O
+.RI [^] feature [,...]
+]
+[
+.B \-U
.I UUID
]
device
.SH DESCRIPTION
.BI tune2fs
adjusts tunable filesystem parameters on a Linux second extended filesystem.
-.PP
-.B Never use tune2fs on a read/write mounted filesystem to change parameters!
-.PP
.SH OPTIONS
.TP
-.I -c max-mount-counts
-adjust the maximal mounts count between two filesystem checks.
+.BI \-c " max-mount-counts"
+Adjust the maximal mounts count between two filesystem checks. If
+.I max-mount-counts
+is 0 then the number of times the filesystem is mounted will be disregarded
+by e2fsck and the kernel.
.TP
-.I -e errors-behavior
-change the behavior of the kernel code when errors are detected.
-.I errors-behavior
-can be one of the followings:
-.br
-\ continue\ \ Continue normal execution.
-.br
-\ remount-ro\ Remount the filesystem read-only.
-.br
-\ panic\ \ Causes a kernel panic.
-.TP
-.I -g group
-set the user group which can benefit from the reserved blocks.
-.br
+.BI \-C " mount-count"
+Set the number of times the filesystem has been mounted.
+Can be used in conjunction with -c to force an fsck on
+the filesystem at the next reboot.
+.TP
+.BI \-e " error-behavior"
+Change the behavior of the kernel code when errors are detected.
+.I error-behavior
+can be one of the following:
+.RS 1.2i
+.TP 1.2i
+.B continue
+Continue normal execution.
+.TP
+.B remount-ro
+Remount filesystem read-only.
+.TP
+.B panic
+Cause a kernel panic.
+.RE
+.TP
+.BI \-g " group"
+Set the group which can use reserved filesystem blocks.
+The
.I group
-can be a numerical gid or a group name.
+parameter can be a numerical gid or a group name. If a group name is given,
+it is converted to a numerical gid before it is stored in the superblock.
+.TP
+.B \-i " \fIinterval-between-checks\fR[\fBd\fR|\fBm\fR|\fBw\fR]"
+Adjust the maximal time between two filesystem checks.
+No postfix or
+.B d
+result in days,
+.B m
+in months, and
+.B w
+in weeks. A value of zero will disable the timedependent checking.
+.TP
+.B -j
+Add an ext3 journal to the filesystem. If the
+.B \-J
+option is not specified, the default journal parameters will be used to create
+an appropriately sized journal (given the size of the filesystem)
+stored within the filesystem. Note that you must be using a kernel
+which has ext3 support in order to actually make use of the journal.
+.TP
+.BR \-J " journal-options"
+Override the default ext3 journal parameters. Journal options are comma
+separated, and may take an argument using the equals ('=') sign.
+The following journal options are supported:
+.RS 1.2i
+.TP
+.BI size= journal-size
+Create a journal stored in the filesystem of size
+.I journal-size
+megabytes. The size of the journal must be at least 1024 filesystem blocks
+(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
+and may be no more than 102,400 filesystem blocks.
+There must be enough free space in the filesystem to create a journal of
+that size.
+@JDEV@.TP
+@JDEV@.BI device= external-journal
+@JDEV@Attach the filesystem to the journal block device located on
+@JDEV@.IR external-journal .
+@JDEV@to the filesystem.
+@JDEV@The external
+@JDEV@journal must have been already created using the command
+@JDEV@.IP
+@JDEV@.B mke2fs -O journal_dev
+@JDEV@.IR external-journal.
+@JDEV@.IP
+@JDEV@Note that
+@JDEV@.I external-journal
+@JDEV@must be formatted with the same block
+@JDEV@size as filesystems which will be using it.
+.RE
+@JDEV@.IP
+@JDEV@Only one of the
+@JDEV@.BR size " or " device
+@JDEV@options can be given for a filesystem.
.TP
-.I -i interval-between-checks[d|m|w]
-adjust the maximal time between two filesystem checks.
-No postfix or `d' result in days, `m' in months, and `w' in weeks.
-A value of zero will disable the timedependent checking.
+.B \-l
+List the contents of the filesystem superblock.
.TP
-.I -l
-list the contents of the filesystem superblock.
+.BI \-L " volume-label"
+Set the volume label of the filesystem.
+Ext2 filesystem labels can be at most 16 characters long; if
+.I volume-label
+is longer than 16 characters,
+.B tune2fs
+will truncate it and print a warning.
+.TP
+.BI \-m " reserved-blocks-percentage"
+Set the percentage of reserved filesystem blocks.
+.TP
+.BI \-M " last-mounted-directory"
+Set the last-mounted directory for the filesystem.
+.TP
+.BR \-O " [^]\fIfeature\fR[,...]"
+Set or clear the indicated filesystem features (options) in the filesystem.
+More than one filesystem feature can be cleared or set by separating
+features with commas. Filesystem features prefixed with a
+caret character ('^') will be cleared in the filesystem's superblock;
+filesystem features without a prefix character or prefixed with a plus
+character ('+') will be added to the filesystem.
+.IP
+The following filesystem features can be set or cleared using
+.BR tune2fs :
+.RS 1.2i
+.TP
+.B sparse_super
+Limit the number of backup superblocks to save space on large filesystems.
.TP
-.I -m reserved-blocks-percentage
-adjust the reserved blocks percentage on the given device.
+.B filetype
+Store file type information in directory entries.
+.TP
+.B has_journal
+Create an ext3 journal (as if using the
+.B \-j
+option).
+.RE
+.IP
+After setting or clearing any filesystem feature,
+.BR e2fsck (8)
+must be run on the filesystem to return the filesystem to a consistent state.
+.IP
+.B Warning:
+Linux kernels before 2.0.39 and many 2.1 series kernels do not support
+the filesystems that use any of these features.
+Enabling certain filesystem features may prevent the filesystem from
+being mounted by kernels which do not support those features.
.TP
-.I -r reserved-blocks-count
-adjust the reserved blocks count on the given device.
+.BI \-r " reserved-blocks-count"
+Set the number of reserved filesystem blocks.
.TP
-.I -s sparse_super_flag
-sets and resets the sparse_superblock flag. The sparse_superblock feature
-saves space on really big filesystems.
+.BR \-s " [" 0 | 1 ]
+Turn the sparse super feature off or on. Turning this feature on
+saves space on really big filesystems. This is the same as using the
+.B "\-O sparse_super"
+option.
+.IP
.B Warning:
-The Linux 2.0 kernel does not properly support this feature. Neither do
+Linux kernels before 2.0.39 do not support this feature. Neither do
all Linux 2.1 kernels; please don't use this unless you know what you're
-doing!
+doing! You need to run
+.BR e2fsck (8)
+on the filesystem after changing this feature in order to have a valid
+filesystem.
.TP
-.I -u user
-set the user who can benefit from the reserved blocks.
+.BI \-u " user"
+Set the user who can use the reserved filesystem blocks.
.I user
-can be a numerical uid or a user name.
-.IP
-.I -C mount-count
-set the number of times the filesystem has been mounted.
+can be a numerical uid or a user name. If a user name is given, it
+is converted to a numerical uid before it is stored in the superblock.
.TP
-.I -L volume-label
-set the volume label of the filesystem.
+.BI \-U " UUID"
+Set the universally unique identifier (UUID) of the filesystem to
+.IR UUID .
+The format of the UUID is a series of hex digits separated by hypthens,
+like this:
+"c1b9d5a2-f162-11cf-9ece-0020afc76f16".
+The
+.I UUID
+parameter may also be one of the following:
+.RS 1.2i
+.TP
+.I clear
+clear the filesystem UUID
.TP
-.I -M last-mounted-directory
-set the last-mounted direcctory for the filesystem.
+.I random
+generate a new randomly-generated UUID
.TP
-.I -U UUID
-set the UUID of the filesystem. A sample UUID looks like this:
-"c1b9d5a2-f162-11cf-9ece-0020afc76f16". The uuid may also be "null",
-which will set the filesystem UUID to the null UUID. The uuid may also
-be "random", which will generate a new random UUID for the filesystem.
-.PP
+.I time
+generate a new time-based UUID
+.RE
+.IP
+See
+.BR uuidgen (8)
+for more information.
+If the system does not have a good random number generator such as
+.I /dev/random
+or
+.IR /dev/urandom ,
+.B tune2fs
+will automatically use a time-based UUID instead of a randomly-generated UUID.
.SH BUGS
-We didn't find any bugs yet. Perhaps there are bugs but it's unlikely.
-.PP
-.SH WARNING
-.B Use this utility on your own risk. You're modifying filesystems.
+We haven't found any bugs yet. That doesn't mean there aren't any...
.SH AUTHOR
.B tune2fs
-has been written by Remy Card <card@masi.ibp.fr>, the developer and maintainer
-of the ext2 fs.
-.br
+was written by Remy Card <Remy.Card@linux.org>.
.B tune2fs
uses the ext2fs library written by Theodore Ts'o <tytso@mit.edu>.
-.br
This manual page was written by Christian Kuhtz <chk@data-hh.Hanse.DE>.
-.br
Timedependent checking was added by Uwe Ohse <uwe@tirka.gun.de>.
.SH AVAILABILITY
.B tune2fs
-is available for anonymous ftp from ftp.ibp.fr and tsx-11.mit.edu in
-/pub/linux/packages/ext2fs.
+is part of the e2fsprogs package and is available from
+http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR dumpe2fs (8),
.BR e2fsck (8),
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff