F

fdisk
fdisk is the name of a disk partitioning program. Actually it is the name of several disk partitioning programs. Most of them are used on x86 architecture machines. Most of them are character-based.

Microsoft's fdisk program, run from the DOS command line, takes over the screen and has limited commands for creating primary, extended and logical partitions needed for MS Windows 95, 98, ME and so on.

Linux's fdisk program is scroll oriented. It is more flexible than most of the others, being able to create Microsoft extended partitions in primary slots 3 and 4, in addition to BSD and Solaris disklabels, and it can set the partition type to any of the 256 possible values you might need.

Solaris's fdisk program is very limited; it can only create primary partitions. The same program on Solaris/Sparc is provided, although somewhat useless and in fact dangerous.

fdisk programs of different kinds are also supplied with BSD and OS/2.

All of these programs are partly incompatible in subtle ways. It is not unusual for one program to ruin things as seen by another, or as seen by one or another operating system, and it's often hard to tell what's really going on and what's really ruined.The best time to play around with these is when your disk is new, or recently erased, and so damage is minimized.


FIFO
A special device file that represents a named pipe. FIFO stands for First In, First Out, because the bytes that come out the other end first are the same ones that first were written to it.


File
a filesystem object. A directory lists zero or more files that are contained in it. You can see the files in a directory with a Directory window; this is the most common kind of window in Interrogator.

Each file has a filename which is a string of characters. The files in a particular directory usually must have distinct names; that is, no two can have the same name. Kinds of files include Regular Files, Direcctories, Symlinks, and Special Device Files. Each kind of file has a different shaped icon: Regular Files have upright rectangles, Directories have wide rectangles, Symlinks have arrows, etc.


File Mode
Same as the mode bits.


File Name
A character string that identifies a file in its directory.

The rules of file names are different, depending on the filesystem that the file is on. Most filenames use Ascii characters, but for some languages, other character systems such as Unicode are needed.

Unix filesystems are usually case sensitive, that is, Alice, alice, ALICE, and alICE all are different filenames. More popular filesystems, as on MacOS and MS Windows, are case-insensitive, that is, alice and ALICE and other variations are considered to be the same name for the same file.

This means that if you ask for alice you might get ALICE, because that was the file that was there.

Among case-insensitive filesystems, most newer ones retain case, whereas older ones flatten case. If you make a file deCamp on MacOS, for instance, the name will be remembered as just that, deCamp. If you do the same thing on early versions of MS DOS and MS Windows, however, the name will probably be remembered as DECAMP. Many Windows programs try to finesse over this problem by displaying such a file as decamp or Decamp.

The more modern kinds of filesystems allow filenames up to 255 characters long. Typically they store Unicode, either litterally as 16 bit characters, or as a UTF-8 byte stream. The trend is for Unicode, with language-specific case insensitivity and sorting order.

Older file systems have more strict rules. For instance, very old Unix filesystems only had room for 14 character names, and old MacOS filesystems only have room for 31 character names. Before Unix became popular, many systems restricted the kind of characters in filenames, such as RT-11, which allowed letters, digits and five punctuation marks.

FAT16 and FAT32 volumes, found on MS Windows systems, internally only have room for so-called 8.3 filenames, that is, up to 8 characters before the dot and up to 3 characters after the dot. There are other rules, such as having one and only one dot, even if you don't want it, folding case, etc. Starting with Windows 95, another layer of the file system allowed pretty much the usual 255 character names. In Linux, it is best to use this layer by mounting with the filesystem type vfat.

In some versions of Windows, the filename remapping caused problems. If a filename already fit the 8.3 rules, it would be remembered directly. If so, it would lose the case information - directory listings would be all caps or all lower case or whatever a program could guess. The file ViewName will be remembered case-flattened as VIEWNAME, whereas ViewNames will be remapped and remembered with case intact so it would behave normally. And some programs would still work with the internal filenames so ViewNames would be known by its internal name, something like VIEWNA~1. The system also has a strange limitation whereby it sometimes runs out of internal names, right after VIEWN~99.

Windows 2000 and XP tend to use a more modern filesystem called NTFS that is more comparable to a Unix filesystem with 255 characters, Unicode compatibility, etc.


Filesystem
This is an ambiguous term. Sometimes people use it to refer to a volume, sometimes to refer to a kind of volume. We use the term loosely to refer to the part of your computer that stores files, and all of the associated software. This is a big topic, and the main focus of Tactile Interrogator itself.


Filesystem Type
Every volume has a filesystem type that tells how files and data in that volume are organized, and how the OS accesses the data.

Usually filesytem types go along with operating systems, but often different operating systems get drivers to access other filesystem types for intercompatibility. (As you might expect, Microsoft never does this, as it would validate competitors.) The drivers are needed for your currently running OS to mount the disk partition as one of its own. If you access a volume over a network, it appears to you as a network filesystem, not as the original filesystem. For instance, if a machine named tracer serves an EXT3 volume over NFS, it will appear to you as an NFS volume, not an EXT3 volume, and you'll need no such driver.

This is a table that should give you an idea of some of the most common filesystem types around; see man mount for more information on your system. Linux systems in particular are getting more and more different disk filesystem types for various purposes such as journaling or compatibility. NOTE: the information in this table is subject to change and the weaknesses of the author's memory.

filesystem type Typically found description notes Runs on Linux? runs on Solaris? runs on Mac OS X? runs on MS Windows?
EXT2, EXT3 Linux disks Default Linux disk partition intercompatible, upward and downward very well only with special drivers no no
Solaris UFS Solaris disks default Solaris disk partition don't mix up with BSD or OS X flavor read-only, as ufs with special option very well no no
BSD UFS BSD Disks default BSD disk partition don't mix up with Solaris flavor read-only, as ufs with special option no very well no
HFS old MacOS disks default partition for MacOS version 8 and earlier No larger than 2 gigabytes if enabled no yes no
HFS Plus modern MacOS disks default Mac OS X partition MacOS 8.1 and later maybe no very well no
NFS Unix networks Network file serving system files on other machines as nfs as nfs as nfs no
AFP Macintosh networks Appletalk Filing Protocol files on other machines sometimes rarely very well with special driver
SMB MS Windows networks same as NetBIOS files on other machines Samba driver Samba driver Samba driver native Netbios
FAT16 Wintel disks Microsoft file system No larger than 2 gigabytes as vfat as pcfs as msdos very well
FAT32 Wintel disks Microsoft file system   as vfat as pcfs as msdos very well
proc Unix systems Virtual file system that simply displays system process information Each unix's version is slightly different as proc as proc none don't even think about it
ISO 9660 on most CDs platform-independent CD filesystems sometimes includes RockRidge or Joliet extensions as iso9660 as hsfs as cd9660 yes


Format
This word is used in a variety of different ways, usually referring to some kind of rules for arranging and encoding data.

When talking about files and volumes, "to format" means to take a partition, and transform it into a volume. If partitioning is like constructing walls in a building, formatting is like installing shelves and furniture. The root directory of the volume is created during formatting. When done formatting, you are left with a volume with that root directory, possibly a few more directories and files, depending on your OS, and a lot of free space. Most important, though, you can start to create files and directories in it, whereas this was not possible right after partitioning.

Usually on Unix systems, you format with the mkfs command and its variants. See also man mkfs, Filesystem Type.


Full Disclosure Mode
This is a mode where Interrogator displays all information it knows about a selected file or item. See this tutorial entry for more information.


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