newfs is used to initialize and clear file systems before first use. Before running
newfs the disk must be labeled using
disklabel(8).
newfs builds a file system on the specified special device basing its defaults on the information in the disk label. Typically the defaults are reasonable, however
newfs has numerous options to allow the defaults to be selectively overridden.
Options with numeric arguments may contain an optional (case-insensitive) suffix:
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.
t
Tera; multiply the argument by 1099511627776.
The following options define the general layout policies.
-a maxcontig
This sets the obsolete maxcontig parameter.
-B byte-order
Specify the metadata byte order of the file system to be created. Valid byte orders are ‘be' and ‘le'. If no byte order is specified, the file system is created in host byte order.
-b block-size
The block size of the file system, in bytes. It must be a power of two. The smallest allowable size is 4096 bytes. The default size depends upon the size of the file system:
file system size
block-size
-d maxbsize
Set the maximum extent size to maxbsize.
-e maxbpg
This indicates the maximum number of blocks any single file can allocate out of a cylinder group before it is forced to begin allocating blocks from another cylinder group. The default is about one quarter of the total blocks in a cylinder group. See
tunefs(8) for more details on how to set this option.
-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.
-f frag-size
The fragment size of the file system in bytes. It must be a power of two ranging in value between
block-size/8 and
block-size. The optimal
block-size:
frag-size ratio is 8:1. Other ratios are possible, but are not recommended, and may produce unpredictable results. The default size depends upon the size of the file system:
file system size
frag-size
-G
Treat garbage parameters as non-fatal. Using this option may result in a file system which causes a kernel panic and should only be used for testing.
-g avgfilesize
The expected average file size for the file system.
-h avgfpdir
The expected average number of files per directory on the file system.
-I
Do not require that the file system type listed in the disk label is ‘4.2BSD' or ‘Apple UFS'.
-i bytes-per-inode
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 default is to create an inode for every (4 *
frag-size) bytes of data space:
file system size
bytes-per-inode
-m free-space
The percentage of space reserved from normal users; the minimum free space threshold. The default value used is 5%. See
tunefs(8) for more details on how to set this option.
-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 filesystem. If both -i and -n are specified then -n takes precedence.
-O filesystem-format
Select the filesystem-format.
0
4.3BSD; This option is primarily used to build root file systems that can be understood by older boot ROMs.
1
FFSv1; normal fast-filesystem (default). This is also known as ‘FFS', ‘UFS', or ‘UFS1'.
2
FFSv2; enhanced fast-filesystem (suited for more than 1 Terabyte capacity, access control lists). This is also known as ‘UFS2'.
To create an LFS filesystem see
newfs_lfs(8). To create a Linux ext2 filesystem see
newfs_ext2fs(8).
-o optimization
Optimization preference; either “space” or “time”. The file system can either be instructed to try to minimize the time spent allocating blocks, or to try to minimize the space fragmentation on the disk. If the value of minfree (see above) is less than 5%, the default is to optimize for space; if the value of minfree is greater than or equal to 5%, the default is to optimize for time. See
tunefs(8) for more details on how to set this option.
-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 arguments, 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 existing file.
If
size is negative the specified size is subtracted from the default size (reserving space at the end of the partition).
-T disk-type
Uses information for the specified disk from /etc/disktab instead of trying to get the information from the disk label.
-V verbose
This controls the amount of information written to stdout:
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 displayed (no progress bar).
The default is 3. If
-N is specified
newfs stops before outputting the progress bar.
-v volname
This specifies that an Apple UFS filesystem should be created with the given volume name.
-Z
Pre-zeros the file system image created with
-F. This is necessary if the image is to be used by
vnd(4) (which doesn't support file systems with ‘holes').
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 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_ffs(8) to find the alternative superblocks if the standard superblock is lost.
-S sector-size
The size of a sector in bytes (almost never anything but 512). Defaults to 512.