mkfs.8

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)mkfs.8	8.2	9/27/90
.TH mkfs 8
.SH Name
mkfs \- construct a file system
.SH Syntax
.B /etc/mkfs
[ \fI-N\fP ]
\fIspecial size\fP
[ \fInsect\fP ]
[ \fIntrack\fP ]
[ \fIblksize\fP ]
.br
[ \fIfragsize\fP ]
[ \fIncpg\fP ]
[ \fIminfree\fP]
[ \fIrps\fP ]
[ \fInbpi\fP ]
[ \fIopt\fP ]
.SH Description
.NXR "mkfs command"
.NXR "file system" "constructing prototype"
.NXA "mkfs command" "newfs command"
.NXA "mkfs command" "tunefs command"
File systems are normally created with the
.MS newfs 8
command.
.PP
The \fI-N\fP option is used to run
.PN mkfs
in no update mode.  In this mode, 
.PN mkfs
will not write to
.PN special .
.PP
The
.PN mkfs
command constructs a file system
by writing on the special file
.I special.
The numeric size specifies the number of sectors in the file system.
The
.PN mkfs
command builds a file system with a root directory and a
.I lost+found
directory.
For further information, see 
.MS fsck 8 .
The number of i-nodes is calculated
as a function of the file system size.
No boot program is initialized by
.PN mkfs .
For further information, see 
.MS newfs 8 .
.PP
When the on-disks inodes of the file system are written, each contains
a unique number in its generation number field.  This number uniquely
identifies each inode in a file system.
.PP
The optional arguments allow fine tune control over the
parameters of the file system.
The
.I nsect
argument specifies the number of sectors per track on the disk.
The
.I ntrack 
argument specifies the number of tracks per cylinder on the disk.
The
.I blksize 
argument gives the primary block size for files on the file system.
It must be a power of two, currently selected from 4096 or 8192.
The
.I fragsize
argument gives the fragment size for files on the file system.
The
.I fragsize
argument represents the smallest amount of disk space
that will be allocated to a file.
It must be a power of two currently selected from the range 512 to 8192.
The
.I ncpg
argument specifies the number of disk cylinders per cylinder group.
This number must be in the range 1 to 32.
The
.I minfree
argument specifies the minimum percentage of free disk space allowed.
Once the file system capacity reaches this threshold, only
the superuser is allowed to allocate disk blocks.  The default
value is 10%.
If a disk does not revolve at 60 revolutions per second, the
.I rps
parameter may be specified.
Users with special demands for their file systems are referred to
``A Fast File System for UNIX'' in the
.I "ULTRIX Supplementary Documents, Volume 3: System Manager"
for a discussion of the tradeoffs in using different configurations.
The
.I nbpi
argument specifies the number (ratio) of bytes per inode. 
The default is 2048 bytes.  
The
.I opt
argument is used to indicate the whether the 
file system should optimize for
space or time.
The
.I opt
argument can be assigned a value of s or t.
.SH Restrictions
If 
.PN /bin/mkfs
is invoked without arguments, 
the RISC machines dump core instead of returning an error.
.SH See Also
dir(5), fs(5), fsck(8), newfs(8), tunefs(8)
.br
"A Fast File System for UNIX",
\fISupplementary Documents, Volume 3: System Manager\fP