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Manual page for PCFS(4S)

PCFS - MS-DOS formatted filesystem


options PCFS


Available only on Sun-3/80, and Desktop SPARCsystems with internal floppy drives.


PCFS is a filesystem type that allows users direct access to files on MS-DOS formatted disks from within the SunOS operating system. Once mounted, a PCFS filesystem provides standard SunOS file operations and semantics. That is, users can create, delete, read, write files on an MS-DOS formatted disk. They can also create/delete directories and list files in a directory.

PCFS filesystems are mounted either with the command:

mount -t pcfs device-special directory-name


mount /pcfs

if the following line

/dev/fd0 /pcfs pcfs rw,noauto 0 0

is in your /etc/fstab.

File and directories created through PCFS have to comply with the MS-DOS file name convention, which is of the form filename[.ext], where filename consists of one through eight upper-case characters, while the optional ext consists of one through three upper-case characters. PCFS converts all the lower-case characters in a file name to upper-case, and chops off any extra characters in filename or ext. When displaying file names, PCFS only shows them in lower-case.

One can use either the MS-DOS FORMAT command, or

fdformat -d

command in the SunOS system to format a diskette in MS-DOS format.


If you copy a file


from a UNIX filesystem to a PCFS filesystem, it will show up as


on the MS-DOS disk.

The following file names




are considered illegal in MS-DOS, therefore can not be created through PCFS.


The following are all the legal characters that are allowed in file names or extentions in PCFS:

0-9, a-z, A-Z, and $#&@!%()-{}<>`_\^~|'

Since SunOS and DOS operating systems use different character sets, and have different requirements for the text file format, one can use




command to convert files between them.

PCFS offers a convenient transportation vehicle for files between Sun Workstations and PC's. Since the MS-DOS disk format was designed for use under DOS, it is quite inefficient to operate under the SunOS system. Therefore, it should not be used as the format for a regular local storage. You should use ufs for local storage within the SunOS system.




dos.1 dos2unix.1 eject.1 fd.4 fdformat(1), unix2dos.1 fstab.5 mount.8


mount.8 will fail and produce the following message:
mount_pcfs: /dev/fd0 on /pcfs type pcfs: Invalid argument
if the floppy in the fd0 drive is not in MS-DOS format. For example, if you try to mount a ufs formatted floppy as a PCFS filesystem.
mount_pcfs: /dev/fd0 on /pcfs type pcfs: No such device
if configuration option options PCFS is missing from the kernel.


It is not recommended to physically eject an MS-DOS floppy while the device is still mounted as a PCFS filesystem.

Since PCFS truncates any extra characters in file names and extentions like MS-DOS, be careful when copying files from a UNIX filesystem to a PCFS filesystem. For instance, the following two files

test.data1 test.data2

in a UNIX filesystem will get copied to the same file


in PCFS.


PCFS should handle the disk change condition like MS-DOS, so that the user does not need to unmount the filesystem to change floppies. PCFS is currently not NFS mountable. Trying to mount a PCFS filesystem through NFS will fail with an EACCES error.

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Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).

Last modified 21/April/97