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NEWFS_EXT2FS(8) NetBSD System Manager's Manual NEWFS_EXT2FS(8)
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newfs_ext2fs -- construct a new ext2 file system
newfs_ext2fs [-FINZ] [-b block-size] [-D inodesize] [-f frag-size]
[-i bytes-per-inode] [-m free-space] [-n inodes]
[-O filesystem-format] [-S sector-size] [-s size]
[-V verbose] [-v volname] special
newfs_ext2fs is used to initialize and clear ext2 file systems before
first use. Before running newfs_ext2fs the disk must be labeled using
disklabel(8). newfs_ext2fs builds a file system on the specified special
device basing its defaults on the information in the disk label. Typi-
cally the defaults are reasonable, however newfs_ext2fs has numerous
options to allow the defaults to be selectively overridden.
Options with numeric arguments may contain an optional (case-insensitive)
b Bytes; causes no modification. (Default)
k Kilo; multiply the argument by 1024.
m Mega; multiply the argument by 1048576.
g Giga; multiply the argument by 1073741824.
The following options define the general layout policies.
The block size of the file system, in bytes. It must be a
power of two. The smallest allowable size is 1024 bytes.
The default size depends upon the size of the file system:
file system size block-size
<= 512 MB 1 KB
> 512 MB 4 KB
Set the inode size. Defaults to 128, and can also be set to
256 for compatibility with ext4.
-F Create a file system image in special. The file system size
needs to be specified with ``-s size''. No attempts to use
or update the disk label will be made.
The fragment size of the file system in bytes. It must be
the same with blocksize because the current ext2fs implemen-
tation doesn't support fragmentation.
-I Do not require that the file system type listed in the disk
label is `Linux Ext2'.
This specifies the density of inodes in the file system. If
fewer inodes are desired, a larger number should be used; to
create more inodes a smaller number should be given.
The percentage of space reserved from normal users; the mini-
mum free space threshold. The default value used is 5%.
-N Causes the file system parameters to be printed out without
really creating the file system.
-n inodes This specifies the number of inodes for the file system. If
both -i and -n are specified then -n takes precedence. The
default number of inodes is calculated from a number of
blocks in the file system.
Select the filesystem-format.
0 `GOOD_OLD_REV'; this option is primarily used to
build root file systems that can be understood by
old or dumb firmwares for bootstrap.
1 `DYNAMIC_REV'; the default. Various extended (and
sometimes incompatible) features are enabled
(though not all features are supported on NetBSD).
Currently only the following features are sup-
RESIZE Prepare some reserved struc-
tures which enable future file
FTYPE Store file types in directory
entries to improve performance.
SPARSESUPER Prepare superblock backups for
the fsck_ext2fs(8) utility on
not all but sparse block
LARGEFILE Enable files larger than 2G
-s size The size of the file system in sectors. An `s' suffix will
be interpreted as the number of sectors (the default). All
other suffixes are interpreted as per other numeric argu-
ments, except that the number is converted into sectors by
dividing by the sector size (as specified by -S secsize)
after suffix interpretation.
If no -s size is specified then the filesystem size defaults
to that of the partition, or, if -F is specified, the exist-
If size is negative the specified size is subtracted from the
default size (reserving space at the end of the partition).
-V verbose This controls the amount of information written to stdout:
0 No output.
1 Overall size and cylinder group details.
2 A progress bar (dots ending at right hand margin).
3 The first few super-block backup sector numbers
are displayed before the progress bar.
4 All the super-block backup sector numbers are dis-
played (no progress bar).
The default is 3. If -N is specified newfs_ext2fs stops
before outputting the progress bar.
-v volname This specifies a volume name for the file system.
-Z Pre-zeros the file system image created with -F.
The following option overrides the standard sizes for the disk geometry.
The default value is taken from the disk label. Changing this default is
useful only when using newfs_ext2fs to build a file system whose raw
image will eventually be used on a different type of disk than the one on
which it is initially created (for example on a write-once disk). Note
that changing this value from its default will make it impossible for
fsck_ext2fs(8) to find the alternative superblocks if the standard
superblock is lost.
The size of a sector in bytes (almost never anything but
512). Defaults to 512.
There is no option to specify the metadata byte order on the file system
to be created because the native ext2 file system is always little endian
even on big endian hosts.
The file system is created with `random' inode generation numbers to
improve NFS security.
The owner and group IDs of the root node and reserved blocks of the new
file system are set to the effective UID and GID of the user initializing
the file system.
For the newfs_ext2fs command to succeed, the disk label should first be
updated such that the fstype field for the partition is set to
`Linux Ext2', unless -F or -I is used.
The partition size is found using fstat(2), not by inspecting the disk
label. The block size and fragment size will be written back to the disk
label only if the last character of special references the same partition
as the minor device number.
fstat(2), disklabel(5), disktab(5), fs(5), disklabel(8), diskpart(8),
fsck_ext2fs(8), mount(8), mount_ext2fs(8), newfs(8)
Remy Card, Theodore Ts'o, and Stephen Tweedie, "Design and Implementation
of the Second Extended Filesystem", The Proceedings of the First Dutch
International Symposium on Linux,
The newfs_ext2fs command first appeared in NetBSD 5.0.
The newfs_ext2fs command was written by Izumi Tsutsui
The newfs_ext2fs command is still experimental and there are few sanity
The newfs_ext2fs command doesn't have options to specify each REV1 file
system feature independently.
The newfs_ext2fs command doesn't support the bad block list accounted by
the bad blocks inode.
Many newer ext2 file system features (especially journaling) are not sup-
Some features in file systems created by the newfs_ext2fs command might
not be recognized properly by the fsck_ext2fs(8) utility.
There is no native tool in the NetBSD distribution for resizing ext2 file
NetBSD 9.1 April 13, 2019 NetBSD 9.1