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newfs(8) [bsd man page]

NEWFS(8)						      System Manager's Manual							  NEWFS(8)

NAME
newfs - construct a new file system SYNOPSIS
/sbin/newfs [ -N ] [ -m free-gap ] [ -n free-modulus ] [ -i bytes ] [ -s size ] [ -T disk-type ] special DESCRIPTION
Newfs is a ``friendly'' front-end to the mkfs(8) program. Newfs(8) will normally read the disklabel from the drive to determine the parti- tion sizes. If the driver for the disk does not support disklabels the -T option must be used to force a search of /etc/disktab for parti- tion information about drive-type. Newfs calculates the appropriate parameters to use in calling mkfs, then builds the file system by forking mkfs. -N causes the mkfs command which would be executed to be printed out without actually creating the file system. The disk specified by spe- cial must be online though so that newfs can read the disklabel. -m allows the specification of the block interleaving of the free list. If not specified or outside the range 1 thru 32 then a value of 2 is used. -n parameter is the freelist modulus (when the -m pattern repeats) and is calculated by newfs to be 1 cylinder in size by default. -i specifies how many bytes per inode to assume when calculating how many inodes to allocate. The default is 4096 bytes per inode. If this results in too few inodes being allocated (there is an absolute maximum of 65500) then decrease the bytes number (which must lie between 512 and 65536). -T must be used if the disk specified by special has not been labeled with the disklabel(8) program. In this case disk-type is used by getdisklabel(3) when searching /etc/disktab. This option is used when the underlying device driver does not support disklabels. Care must be taken that the contents of /etc/disktab match the partition tables in the kernel. -s specifies how many sectors the file system is to contain. There are two sectors per file system block, therefore size should be even. This parameter must be less than or equal to the partition size (as determined from the disklabel or /etc/disktab). An error is printed and no action is taken if the partition size is 0 or too large. NOTE: Mkfs deals in units of filesystem blocks not sectors. Newfs uses sectors. FILES
/etc/disktab disk geometry and partition information mkfs to actually build the file system SEE ALSO
getdisklabel(3), disklabel(8), disktab(5), diskpart(8), fs(5), fsck(8), mkfs(8) BUGS
newfs(8) no longer places boot blocks on the filesystem. That duty has been moved to the disklabel(8) program. If you must place a boot block on a disk whose driver does not support disklabels use dd(1). 4.2 Berkeley Distribution April 12, 1996 NEWFS(8)

Check Out this Related Man Page

disklabel(4)						     Kernel Interfaces Manual						      disklabel(4)

NAME
disklabel - Disk pack label SYNOPSIS
#include <sys/disklabel.h> DESCRIPTION
Each disk or disk pack on a system may contain a disk label which provides detailed information about the geometry of the disk and the par- titions into which the disk is divided. It should be initialized when the disk is formatted, and may be changed later with the disklabel program. This information is used by the system disk driver and by the bootstrap program to determine how to program the drive and where to find the file systems on the disk partitions. Additional information is used by the file system in order to use the disk most effi- ciently and to locate important file system information. The description of each partition contains an identifier for the partition type (standard file system, swap area, etc.). The file system updates the in-core copy of the label if it contains incomplete information about the file system. The label is located in sector number LABELSECTOR of the drive, usually sector 0 (zero) where it may be found without any information about the disk geometry. It is at an offset LABELOFFSET from the beginning of the sector, to allow room for the initial bootstrap. The disk sector containing the label is normally made read-only so that it is not accidentally overwritten by pack-to-pack copies or swap opera- tions; the DIOCWLABEL ioctl, which is done as needed by the disklabel program, allows modification of the label sector. A copy of the in-core label for a disk can be obtained with the DIOCGDINFO ioctl; this works with a file descriptor for a block or charac- ter (raw) device for any partition of the disk. The in-core copy of the label is set by the DIOCSDINFO ioctl. The offset of a partition cannot generally be changed, nor made smaller while it is open. One exception is that any change is allowed if no label was found on the disk, and the driver was able to construct only a skeletal label without partition information. Finally, the DIOCWDINFO ioctl operation sets the in-core label and then updates the on-disk label; there must be an existing label on the disk for this operation to succeed. Thus, the initial label for a disk or disk pack must be installed by writing to the raw disk. All of these operations are normally done using the disklabel program. RELATED INFORMATION
Files: disktab(4) Commands: disklabel(8) delim off disklabel(4)

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