PCFS(4S)

NAME
PCFS - MS-DOS formatted filesystem

CONFIG
options PCFS

AVAILABILITY

Available only on Sun-3/80, and 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 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

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 SunOS 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 SunOS 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 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.

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.