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.TH VOLD 1 "March 1997"
.SH NAME
vold \- Volume daemon for mounting cdroms etc.
.SH SYNOPSIS
.B vold [-d
.IB debug-level "] [-fh] [-p"
.IB period "] [-s_]"
.SH DESCRIPTION
.IX vold
.LP
.B Vold
is a daemon that attempts to mount removable media (such as CDROM)
automatically upon insertion. It does this by opening these devices at
regular time intervals (default 5 seconds), trying to read data. If
this succeeds the
.I volume name
of the medium is scanned for. A directory typically called
.BI /cdrom/ volume-name
is created, and the cdrom is mounted at that point.
.LP
.B vold
opens a pipe at the location
.I /var/run/vold.pipe
waiting for commands. This pipe is written to typically by the program
.BR volq .
Commands may involve unmounting and ejecting a cdrom specified by
the volume name.
.SH OPTIONS
.IP "-d debug-level"
Set debug level. Level 1 prints basic progress to stderr, higher debug
levels are for development.
.IP "-f"
Don't fork to background, but stay in the foreground. This may
be useful for debugging purposes.
.IP "-h"
Print copyright information and terse help.
.IP "-p period"
Set the delay period between successive attempts to read from the
devices. Default is 5 seconds, so it may take up to this period before
a cdrom is mounted after you've inserted it.
.IP "-s"
Be strict about the volume names. According to ISO 9660, a volume
name may contain only characters from [A-Z0-9_], i.e., no lowercase
characters. However, many implementations don't really care. By
setting this options, only characters matching [A-Z0-9_]+ from the
start of the volume name are accepted.
.IP "-_"
Use underscores for volume names containing spaces. If a volume name
contains blanks, e.g.,
.BR "Debian 1.3.1 Binary" ,
translate the blanks into underscore characters
.BR _ .
Note that in the mounttab, this conversion will always take place,
because otherwise
.BI mount (2)
gets confused.
.SH CONFIGURATION FILE
In a file
.I /etc/voltab
the locations of the devices that are scanned for removable media are
tabulated. The format of this file is similar to that of
.IR /etc/fstab .
A typical voltab file looks like
/dev/cm206cd /cdrom iso9660 ro 0 0
.br
/dev/hdb /cdrom iso9660 ro,nosuid 0 0
This example shows a configuration of 2 drives, the cheap and obsolete
Philips/LMS cm206 drive, and a nowadays even cheaper IDE ATAPI cdrom
drive. If you have a CD labeled
.I GNU
it will be mounted under
.I /cdrom/gnu
independently of which drive you put the CD in.
.SH REASON FOR EXISTENCE
The
.B vold
daemon was conceived after SUN's principle of mounting cdroms under the
location indicated above. The author believed that SUN's original
meaning must have been to mount all cdroms on the local network under
the same root
.IR /cdrom .
The idea is that cdroms tend to move around from one machine to
another as soon as you have more cdroms than cdrom drives on your
network, and more than one cdrom drive in total. One generally
replaces the least needed cdrom by one not currently in one of the
drives on the network, that happens to be needed at that time. A user
doesn't want to be concerned with where the cdrom is located, he or
she just wants a uniform way to specify a file on the cdrom.
.LP
At this moment, a network-wide implementation has not been written,
yet. The idea is that the pipe could be replaced by a socket receiving
commands across the network. However, it is possible to have a uniform
cdrom file access by the above method, if you are lucky enough to have
more than one cdrom drive on your machine. Then, you need not be
concerned with which drive you put your CD in.
.SH SEE ALSO
.BR volq (1),
.BR mount (1),
.BR fstab (5).
.LP
.SH DIAGNOSTICS
.LP
The program forks itself into the background. There are several
reasons why things may go wrong. For instance, the device may already
be mounted at some place before
.B vold
is started. Errors are reported to stderr, instead of trying to use
the syslog service.
.SH BUGS
The author has only one cdrom, so multiple cdroms aren't tested, but
should work in principle.
Floppy support has not been written, yet. Implementation very much
depends on the fact if we can detect the existence of a floppy in the
drive without having to read data (this would be too ugly).
.SH AVAILABILITY
.SH PORTABILITY
.B Vold
is written specifically for Linux as the author is much obliged to the
project and strongly believes in supporting it, but maybe it is easy
to port to other systems. The program depends heavily an the
availability of Linux-specific ioctls for CDROM, which are implemented
only for a number of cdrom devices (among which IDE and SCSI) in the
later 2.1 kernels. In fact, the author of
.B vold
has written a generic interface for Linux cdroms because when he
started to write vold, cdrom ioctlling was a mess.
It might be possible to detect the existence of a cdrom in a drive on
other systems, as well as whether or not a media change has occurred.
.SH FILES
.I /etc/voltab
.RS
The table containing a list of devices that
.B vold
operates on.
.RE
.I /var/run/vold.pipe
.RS
The pipe receiving commands
.RE
.I /var/run/vold.pid
.RS
The pid of the daemon
.RE
.SH AUTHOR
.B Vold
is writen and copyrighted by David A. van Leeuwen (david@ElseWare.cistron.nl).
.B Vold
is available under the conditions of the Gnu Public Licence, version 2.
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