mkfs_hfs(1M) mkfs_hfs(1M)
NAME
mkfs_hfs: mkfs - construct an HFS file system
SYNOPSIS
specific_options] special
[size [nsect ntrack blksize fragsize ncpg minfree rps nbpi]]
specific_options]
special [proto [nsect ntrack blksize fragsize ncpg minfree rps nbpi]]
special
Remarks
HFS file systems are normally created with the command (see newfs_hfs(1M)).
DESCRIPTION
The command constructs an HFS file system by writing on the special file special. The command builds the file system with a root directory
and a directory (see fsck_hfs(1M)). The magic number for the file system is stored in the superblock.
The command creates the file system with a rotational delay value of zero (see tunefs(1M)).
Options
recognizes the following options:
Specify the HFS file system type.
This option allows the
command to make the new file system in an ordinary file. In this case, special is the name of an existing file in
which to create the file system. When this option is used, the size of the new file system cannot be defaulted. It
must either be specified on the command line following special, or if a prototype file is being used, it must be the
second token in the prototype file as usual.
There are two types of HFS file systems,
distinguished mainly by directory formats that place different limits on the length of file names.
If is specified, build a long-file-name file system that allows directory entries (file names) to be up to(255)
bytes long.
If is specified, build a short-file-name file system that allows directory entries (file names) to be up to(14)
bytes long.
If neither nor is specified, build a file system of the same type as the root file system.
Display the command line that was used to create the file system.
The file system must already exist. This option provides a means to determine the parameters used to construct the
file system.
Echo the completed command line, but perform no other action.
The command line is generated by incorporating the user-specified options and other information derived from This
option allows the user to verify the command line.
Specify a list of comma separated
suboptions and/or keyword/attribute pairs from the list below.
Controls the
largefile featurebit for the file system. The default is This means the bit is not set, and files created on the file system
will be limited to less than 2 gigabytes in size. If is specified, the bit is set and the maximum size for files created on
the file system is not limited to 2 gigabytes (see mount_hfs(1M) and fsadm_hfs(1M)).
Arguments
recognizes the following arguments:
special The file name of a special file.
One of the following arguments can be included after special:
size The number of blocks in the file system. is defined in The default value is the size of the entire disk or disk sec-
tion minus any swap or boot space requested.
The size of HFS file systems are limited to 256GB-1 or 268,435,455 blocks.
proto The name of a file that can be opened. The command assumes it is a prototype file and takes its directions from that
file. See "Prototype File Structure" below.
The following optional arguments allow fine-tune control over file system parameters:
nsect The number of sectors per track on the disk. The default value is 32 sectors per track.
ntrack The number of tracks per cylinder on the disk. The default value is 16 tracks per cylinder.
blksize The primary block size for files on the file system. Valid values are: 4096, 8192, 16384, 32768, and 65536. The
default value is 8192 bytes.
fragsize The fragment size for files on the file system. fragsize represents the smallest amount of disk space to be allo-
cated to a file. It must be a power of two no smaller than and no smaller than one-eighth of the file system block
size. The default value is 1024 bytes.
ncpg The number of disk cylinders per cylinder group. This number must be in the range 1 to 32. The default value is 16
cylinders per group.
minfree The minimum percentage of free disk space allowed. The default value is 10 percent.
Once the file system capacity reaches this threshold, only users with appropriate privileges can allocate disk
blocks.
rps The number of disk revolutions per second. The default value is 60 revolutions per second.
nbpi The density of inodes in the file system specified as the number of bytes per inode. The default value is 6144 bytes
per inode.
This number should reflect the expected average size of files in the file system. If fewer inodes are desired, a
larger number should be used; if more inodes are desired, a smaller number should be used.
Note: The number of inodes that will be created in each cylinder group of a file system is approximately the size of
the cylinder group divided by the number of bytes per inode, up to a limit of 2048 inodes per cylinder group. If the
size of the cylinder group is large enough to reach this limit, the default number of bytes per inode will be
increased.
Prototype File Structure
A prototype file describes the initial file structure of a new file system. The file contains tokens separated by spaces or newline char-
acters. It cannot contain comments.
The first token is the name of a file to be copied onto block zero as the bootstrap program (usually If the file name is "", no bootstrap
code is placed on the device. The second token is a number specifying the number of blocks in the file system.
The next three tokens specify the mode, user ID, and group ID of the root directory of the new file system, followed by the initial con-
tents of the root directory in the format described for a directory file below, and terminated with a token.
A file specification consists of four tokens giving the name, mode, user ID, and group ID, and an initial contents field. The syntax of
the initial contents field depends on the mode.
A name token is a file name that is valid for the file system. The root directory does not have a name token.
A mode token is a 6-character string. The first character specifies the type of the file. It can be one of the following characters:
Regular file
Block special file
Character special file
Directory
Symbolic link
Hard link
The second character of a mode token is either or to specify set-user-ID mode or not. The third character of a mode token is either or to
specify the set-group-ID mode or not. The rest of a mode token is a three-digit octal number giving the owner, group, and other read,
write, and execute permissions (see chmod(1)).
The user-ID and group-ID tokens define the owner of the file. These values can be specified numerically or with symbolic names that appear
in the current password and group databases.
Refer to usergroupname(5) to understand the functionality changes with the Numeric User Group Name feature.
Regular file. The initial contents field is the path name of an existing file in the current file system whose contents and size are
copied to the new file.
Block or character special file. The initial contents field is two numeric tokens that specify the major and minor device numbers.
Directory file. The initial contents field is a list of file specifications for the entries in the directory. The list is terminated with
a token. Directories can be nested. For each directory, the command automatically makes the and entries.
Symbolic link. The initial contents field is a path name that is used as the path to which the symbolic link should point.
Hard link. The initial contents field is a path name that is used as the name of a file within the new file system to which the entry
should be linked. The mode, user-ID and group-ID tokens of this entry are ignored; they are taken from the target of the link. The target
of the link must be listed before the entry specifying the link. Hard links to directories are not permitted.
With the exception of the permissions field of the mode token (which is always an octal number), all numeric fields can be specified in
hexadecimal (using a leading octal (using a leading or decimal.
Here is a sample prototype specification. The indentation clarifies the directory recursion.
Access Control Lists
Every file with one or more optional ACL entries consumes an extra (continuation) inode. If you anticipate significant use of ACLs on a
new file system, you can allocate more inodes by reducing the value of nbpi appropriately. The small default value typically causes allo-
cation of many more inodes than are actually necessary, even with ACLs. To evaluate your need for extra inodes, run the command on exist-
ing file systems. For more information on access control lists, see acl(5).
EXAMPLES
Execute the command to create a 32MB HFS file system on the non-LVM disk
Display the command that was used to construct the file system on
Create an HFS file system within a logical volume of a size equal to the size of
WARNINGS
The old option, from prior releases of mkfs(1M), is no longer supported.
mkfs_hfs(1M) cannot be executed specifying creation of a file system on a whole disk if that disk was previously used as an LVM disk. If
you wish to do this, use mediainit(1) to reinitialize the disk first.
The option should be used with care, since older applications will not react correctly when confronted with large files.
AUTHOR
was developed by HP and the University of California, Berkeley.
FILES
List of locations of the superblocks for the created file system.
The command appends entries to this file.
SEE ALSO
chmod(1), bdf(1M), df(1M), fsadm_hfs(1M), fsck(1M), fsck_hfs(1M), fsclean(1M), mkfs(1M), mount_hfs(1M), newfs(1M), newfs_hfs(1M), dir(4),
fstab(4), group(4), passwd(4), symlink(4), acl(5), usergroupname(5).
STANDARDS CONFORMANCE
mkfs_hfs(1M)