.I block-size
]
[
+.B \-d
+.I root-directory
+]
+[
.B \-D
]
[
.I number-of-inodes
]
[
-.B \-d
-.I root-directory
-]
-[
.B \-n
]
[
.B \-e
.I errors-behavior
]
+[
+.B \-z
+.I undo_file
+]
.I device
[
-.I blocks-count
+.I fs-size
]
@JDEV@.sp
@JDEV@.B "mke2fs \-O journal_dev"
@JDEV@]
@JDEV@.I external-journal
@JDEV@[
-@JDEV@.I blocks-count
+@JDEV@.I fs-size
@JDEV@]
.SH DESCRIPTION
.B mke2fs
is used to create an ext2, ext3, or ext4 filesystem, usually in a disk
-partition.
-.I device
-is the special file corresponding to the device (e.g
-.IR /dev/hdXX ).
-.I blocks-count
-is the number of blocks on the device. If omitted,
+partition (or file) named by
+.IR device .
+.PP
+The file system size is specified by
+.IR fs-size .
+If
+.I fs-size
+does not have a suffix, it is interpreted as power-of-two kilobytes,
+unless the
+.B \-b
+.I blocksize
+option is specified, in which case
+.I fs-size
+is interpreted as the number of
+.I blocksize
+blocks. If the fs-size is suffixed by 'k', 'm', 'g', 't'
+(either upper-case or lower-case), then it is interpreted in
+power-of-two kilobytes, megabytes, gigabytes, terabytes, etc.
+If
+.I fs-size
+is omitted,
+.B mke2fs
+will create the file system based on the device size.
+.PP
+If
.B mke2fs
-automagically figures the file system size. If called as
+is run as
+.B mkfs.XXX
+(i.e.,
+.BR mkfs.ext2 ,
+.BR mkfs.ext3 ,
+or
+.BR mkfs.ext4 )
+the option
+.B \-t
+.I XXX
+is implied; so
.B mkfs.ext3
-a journal is created as if the
-.B \-j
-option was specified.
+will create a file system for use with ext3,
+.B mkfs.ext4
+will create a file system for use with ext4, and so on.
.PP
The defaults of the parameters for the newly created filesystem, if not
overridden by the options listed below, are controlled by the
man page for more details about bigalloc.) The default cluster size if
bigalloc is enabled is 16 times the block size.
.TP
+.BI \-d " root-directory"
+Copy the contents of the given directory into the root directory of the
+filesystem.
+.TP
.B \-D
Use direct I/O when writing to the disk. This avoids mke2fs dirtying a
lot of buffer cache memory, which may impact other applications running
.TP
.BI nodiscard
Do not attempt to discard blocks at mkfs time.
-@QUOTA_MAN_COMMENT@.TP
-@QUOTA_MAN_COMMENT@.BI quotatype
-@QUOTA_MAN_COMMENT@Specify which quota type ('usr' or 'grp') is to be
-@QUOTA_MAN_COMMENT@initialized. This option has effect only if the
-@QUOTA_MAN_COMMENT@.B quota
-@QUOTA_MAN_COMMENT@feature is set. Without this extended option, the default
-@QUOTA_MAN_COMMENT@behavior is to initialize both user and group quotas.
+.TP
+.BI quotatype
+Specify which quota type ('usr' or 'grp') is to be
+initialized. This option has effect only if the
+.B quota
+feature is set. Without this extended option, the default
+behavior is to initialize both user and group quotas.
.RE
.TP
.BI \-f " fragment-size"
ratio). This allows the user to specify the number
of desired inodes directly.
.TP
-.BI \-d " root-directory"
-Add the files from the root-directory to the filesystem.
-.TP
.BI \-o " creator-os"
Overrides the default value of the "creator operating system" field of the
filesystem. The creator field is set by default to the name of the OS the
create revision 1 filesystems.
.TP
.B \-S
-Write superblock and group descriptors only. This is useful if all of
+Write superblock and group descriptors only. This is an extreme
+measure to be taken only in the very unlikely case that all of
the superblock and backup superblocks are corrupted, and a last-ditch
-recovery method is desired. It causes
+recovery method is desired by experienced users. It causes
.B mke2fs
-to reinitialize the
-superblock and group descriptors, while not touching the inode table
-and the block and inode bitmaps. The
+to reinitialize the superblock and group descriptors, while not
+touching the inode table and the block and inode bitmaps. The
.B e2fsck
program should be run immediately after this option is used, and there
-is no guarantee that any data will be salvageable. It is critical to
-specify the correct filesystem blocksize when using this option,
-or there is no chance of recovery.
+is no guarantee that any data will be salvageable. Due to the wide
+variety of possible options to
+.BR mke2fs
+that affect the on-disk layout, is critical to specify exactly the same
+the same format options, such as blocksize, fs-type, feature flags, and
+other tunables when using this option, or the filesystem will be further
+corrupted. In some cases, such as filesystems that have been resized,
+or have had features enabled after format time, it is impossible to
+overwrite all of the superblocks corretly, and at least some filesystem
+corruption will occur. It is best to run this on a full copy of the
+filesystem so other options can be tried if this doesn't work.
.\" .TP
.\" .BI \-t " test"
.\" Check the device for bad blocks before creating the file system
If this option is is not specified,
.B mke2fs
will pick a single default usage type based on the size of the filesystem to
-be created. If the filesystem size is less than or equal to 3 megabytes,
+be created. If the filesystem size is less than 3 megabytes,
.B mke2fs
will use the filesystem type
.IR floppy .
-If the filesystem size is greater than 3 but less than or equal to
+If the filesystem size is greater than or equal to 3 but less than
512 megabytes,
.BR mke2fs (8)
will use the filesystem type
Print the version number of
.B mke2fs
and exit.
+.TP
+.BI \-z " undo_file"
+Before overwriting a file system block, write the old contents of the block to
+an undo file. This undo file can be used with e2undo(8) to restore the old
+contents of the file system should something go wrong. If the empty string is
+passed as the undo_file argument, the undo file will be written to a file named
+mke2fs-\fIdevice\fR.e2undo in the directory specified via the
+\fIE2FSPROGS_UNDO_DIR\fR environment variable or the \fIundo_dir\fR directive
+in the configuration file.
+
+WARNING: The undo file cannot be used to recover from a power or system crash.
.SH ENVIRONMENT
.TP
.BI MKE2FS_SYNC
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff