222 lines
4.2 KiB
Plaintext
222 lines
4.2 KiB
Plaintext
.TH DOSSRV 4
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.SH NAME
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dossrv, 9660srv, a:, b:, c:, d:, 9fat:, dosmnt, eject \- DOS and ISO9660 file systems
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.SH SYNOPSIS
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.B dossrv
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[
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.B -rsv
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] [
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.B -f
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.I file
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] [
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.I service
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]
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.PP
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.B 9660srv
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[
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.B -9Jsv
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] [
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.B -c
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.I clusters
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] [
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.B -f
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.I file
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] [
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.I service
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]
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.PP
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.B a:
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.PP
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.B b:
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.PP
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.B c:
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.PP
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.B 9fat:
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.PP
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.B dosmnt
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.I n
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.I mtpt
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.PP
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.B eject
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[
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.I n
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]
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.SH DESCRIPTION
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.I Dossrv
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is a file server that interprets DOS file systems.
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A single instance of
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.I dossrv
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can provide access to multiple DOS disks simultaneously.
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.PP
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.I Dossrv
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posts a file descriptor named
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.I service
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(default
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.BR dos )
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in the
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.B /srv
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directory.
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To access the DOS file system on a device, use
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.B mount
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with the
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.I spec
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argument
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(see
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.IR bind (1))
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the name of the file holding raw DOS file system, typically the disk.
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If
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.I spec
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is undefined in the
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.BR mount ,
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.I dossrv
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will use
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.I file
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as the default name for the device holding the DOS system.
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.PP
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Normally
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.I dossrv
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creates a pipe to act as the communications channel between
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itself and its clients.
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The
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.B -s
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flag instructs
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.I dossrv
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to use its standard input and output instead.
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The kernels use this option if they are booting from a DOS disk.
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This flag also prevents the creation of an explicit service file in
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.BR /srv .
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.PP
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The
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.B -v
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flag causes verbose output for debugging, while
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the
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.B -r
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flag makes the file system read-only.
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.PP
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The shell script
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.I a:
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contains
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.IP
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.EX
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unmount /n/a: >[2] /dev/null
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mount -c /srv/dos /n/a: /dev/fd0disk
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.EE
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.LP
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and is therefore a shorthand for mounting a floppy disk in drive A.
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The scripts
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.I b:
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and
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.I dosmnt
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are similar,
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mounting the second floppy disk
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and the
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.IR n th
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non-floppy DOS partition,
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respectively.
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.I C:
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and
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.I d:
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call
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.I dosmnt
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in an attempt to name the drives in
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the same order that Microsoft operating systems do.
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.I 9fat:
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provides access to the FAT component of the Plan 9 partition (see
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.IR prep (8)).
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.PP
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The file attribute flags used by the DOS file system
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do not map directly to those used by Plan 9.
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Since there is no concept of user or group,
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permission changes via
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.B wstat
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(see
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.IR stat (2))
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will fail unless the same (read, write, execute) permissions
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are specified for user, group, and other.
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For example, removing write permission in Plan 9
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corresponds to setting the read-only
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attribute in the DOS file system.
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Most of the other DOS attributes
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are not accessible.
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.PP
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Setting the exclusive use flag (DMEXCL)
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in Plan 9 corresponds to setting the
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system use attribute in the DOS file system.
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Such files are not actually restricted to exclusive use,
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but do merit special treatment that
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helps in the creation of boot disks:
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when
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.I dossrv
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allocates a new block for such a file
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(caused, say, by a write that fills the file's
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last allocated block), it succeeds only if it can
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arrange for the file to be stored
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contiguously on disk.
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.PP
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Since other operating systems do not
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guarantee that system files are laid
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out contiguously, the DMAPPEND mode
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bit is set in file stat information
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only when the file is currently contiguous.
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Attempts to set the DMAPPEND mode bit
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explicitly will cause
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.I dossrv
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to try to make the file contiguous,
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succeeding only if this is possible.
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.PP
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.I 9660srv
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is similar to
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.I dossrv
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in specification, except that it interprets ISO9660 CD-ROM
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file systems instead of DOS file systems.
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Some CDs contain multiple directory trees describing
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the same set of files.
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.IR 9660srv 's
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first choice in such a case is a standard ISO9660 tree
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with Plan 9 system use fields;
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the second choice is a Microsoft ``Joliet'' tree, which
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allows long file names and Unicode characters;
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the third choice is a standard ISO9660 or High Sierra tree.
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The
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.B -9
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flag causes
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.I 9660srv
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to ignore the Plan 9 system use fields,
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while the
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.B -J
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flag causes it to
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ignore the Joliet tree.
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The
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.B -c
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option sets the size of the RAM cache to
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.I clusters
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clusters of 128KB.
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The default
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.I clusters
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is 16,
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but a value of 5600 will cache an entire CD incrementally.
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.PP
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If the floppy drive has an ejection motor,
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.I eject
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will spit out the floppy from drive
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.IR n ,
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default 0.
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.SH EXAMPLE
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Mount a floppy disk with a DOS file system on it.
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.IP
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.EX
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a:
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.EE
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.SH "SEE ALSO"
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.IR kfs (4)
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.SH SOURCE
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.B /sys/src/cmd/dossrv
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.br
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.B /sys/src/cmd/9660srv
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.br
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.B /rc/bin/eject
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.SH BUGS
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The overloading of the semantics of
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the DMEXCL and DMAPPEND
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bits can be confusing.
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