Subversion Repositories planix.SVN

.TH DOSSRV 4

.SH NAME

dossrv, 9660srv, a:, b:, c:, d:, 9fat:, dosmnt, eject \- DOS and ISO9660 file systems

.SH SYNOPSIS

.B dossrv

[

.B -rsv

] [

.B -f

.I file

] [

.I service

]

.PP

.B 9660srv

[

.B -9Jsv

] [

.B -c

.I clusters

] [

.B -f

.I file

] [

.I service

]

.PP

.B a:

.PP

.B b:

.PP

.B c:

.PP

.B 9fat:

.PP

.B dosmnt

.I n

.I mtpt

.PP

.B eject

[

.I n

]

.SH DESCRIPTION

.I Dossrv

is a file server that interprets DOS file systems.

A single instance of

.I dossrv

can provide access to multiple DOS disks simultaneously.

.PP

.I Dossrv

posts a file descriptor named

.I service

(default

.BR dos )

in the

.B /srv

directory.

To access the DOS file system on a device, use

.B mount

with the

.I spec

argument

(see

.IR bind (1))

the name of the file holding raw DOS file system, typically the disk.

If

.I spec

is undefined in the

.BR mount ,

.I dossrv

will use

.I file

as the default name for the device holding the DOS system.

.PP

Normally

.I dossrv

creates a pipe to act as the communications channel between

itself and its clients.

The

.B -s

flag instructs

.I dossrv

to use its standard input and output instead.

The kernels use this option if they are booting from a DOS disk.

This flag also prevents the creation of an explicit service file in

.BR /srv .

.PP

The

.B -v

flag causes verbose output for debugging, while

the

.B -r

flag makes the file system read-only.

.PP

The shell script

.I a:

contains

.IP

.EX

unmount /n/a: >[2] /dev/null

mount -c /srv/dos /n/a: /dev/fd0disk

.EE

.LP

and is therefore a shorthand for mounting a floppy disk in drive A.

The scripts

.I b:

and

.I dosmnt

are similar,

mounting the second floppy disk

and the

.IR n th

non-floppy DOS partition,

respectively.

.I C:

and

.I d:

call

.I dosmnt

in an attempt to name the drives in

the same order that Microsoft operating systems do.

.I 9fat:

provides access to the FAT component of the Plan 9 partition (see

.IR prep (8)).

.PP

The file attribute flags used by the DOS file system

do not map directly to those used by Plan 9.

Since there is no concept of user or group,

permission changes via

.B wstat

(see

.IR stat (2))

will fail unless the same (read, write, execute) permissions

are specified for user, group, and other.

For example, removing write permission in Plan 9

corresponds to setting the read-only

attribute in the DOS file system.

Most of the other DOS attributes

are not accessible.

.PP

Setting the exclusive use flag (DMEXCL)

in Plan 9 corresponds to setting the

system use attribute in the DOS file system.

Such files are not actually restricted to exclusive use,

but do merit special treatment that

helps in the creation of boot disks:

when 

.I dossrv

allocates a new block for such a file

(caused, say, by a write that fills the file's

last allocated block), it succeeds only if it can

arrange for the file to be stored

contiguously on disk.

.PP

Since other operating systems do not

guarantee that system files are laid

out contiguously, the DMAPPEND mode

bit is set in file stat information

only when the file is currently contiguous.

Attempts to set the DMAPPEND mode bit

explicitly will cause 

.I dossrv

to try to make the file contiguous,

succeeding only if this is possible.

.PP

.I 9660srv

is similar to

.I dossrv

in specification, except that it interprets ISO9660 CD-ROM

file systems instead of DOS file systems.

Some CDs contain multiple directory trees describing

the same set of files.

.IR 9660srv 's

first choice in such a case is a standard ISO9660 tree

with Plan 9 system use fields;

the second choice is a Microsoft ``Joliet'' tree, which

allows long file names and Unicode characters;

the third choice is a standard ISO9660 or High Sierra tree.

The

.B -9

flag causes

.I 9660srv

to ignore the Plan 9 system use fields,

while the

.B -J

flag causes it to

ignore the Joliet tree.

The

.B -c

option sets the size of the RAM cache to

.I clusters

clusters of 128KB.

The default

.I clusters

is 16,

but a value of 5600 will cache an entire CD incrementally.

.PP

If the floppy drive has an ejection motor,

.I eject

will spit out the floppy from drive

.IR n ,

default 0.

.SH EXAMPLE

Mount a floppy disk with a DOS file system on it.

.IP

.EX

a:

.EE

.SH "SEE ALSO"

.IR kfs (4)

.SH SOURCE

.B /sys/src/cmd/dossrv

.br

.B /sys/src/cmd/9660srv

.br

.B /rc/bin/eject

.SH BUGS

The overloading of the semantics of

the DMEXCL and DMAPPEND

bits can be confusing.