NAME

PCFS − MS-DOS formatted filesystem

CONFIG

options PCFS

AVAILABILITY

Available only on Desktop SPARCsystems with internal floppy drives. 

DESCRIPTION

PCFS is a filesystem type that allows users direct access to files on MS-DOS formatted disks from within the OS/MP operating system.  Once mounted, a PCFS filesystem provides standard OS/MP 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

or

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 OS/MP system to format a diskette in MS-DOS format. 

EXAMPLES

If you copy a file

financial.data

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

FINANCIA.DAT

on the MS-DOS disk. 

The following file names

.login

test.sh.orig

data+

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

NOTES

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 OS/MP and DOS operating systems use different character sets, and have different requirements for the text file format, one can use

dos2unix

or

unix2dos

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 OS/MP system.  Therefore, it should not be used as the format for a regular local storage.  You should use ufs for local storage within the OS/MP system. 

FILES

/usr/etc/mount_pcfs

SEE ALSO

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

DIAGNOSTICS

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. 

WARNINGS

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

TEST.DAT

in PCFS. 

BUGS

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. 

Solbourne Computer, Inc.  —  11 May 1992