Content-type: text/html Manpage of READCD

READCD

Section: Schily\'s USER COMMANDS (1)
Updated: Version 1.8.1
Index Return to Main Contents
 

NAME

readcd - read or write data Compact Discs  

SYNOPSIS

readcd dev=device [ options ]

 

DESCRIPTION

Readcd is used to read or write Compact Discs.

The device refers to scsibus/target/lun of the drive. Communication on SunOS is done with the SCSI general driver scg. Other operating systems are using a library simulation of this driver. Possible syntax is: dev= scsibus,target,lun or dev= target,lun. In the latter case, the drive has to be connected to the default SCSI bus of the machine. Scsibus, target and lun are integer numbers. Some operating systems or SCSI transport implementations may require to specify a filename in addition. In this case the corect syntax for the device is: dev= devicename:scsibus,target,lun or dev= devicename:target,lun. If the name of the device node that has been specified on such a system referres to exactly one SCSI device, a shorthand in the form dev= devicename:@ or dev= devicename:@,lun may be used instead of dev= devicename:scsibus,target,lun.

To make readcd portable to all UNIX platforms, the syntax dev= devicename:scsibus,target,lun is preferred as is hides OS specific knowledge about device names from the user. A specific OS must not necessarily support a way to specify a real device file name nor a way to specify scsibus,target,lun.

Scsibus 0 is the default SCSI bus on the machine. Watch the boot messages for more information or look into /var/adm/messages for more information about the SCSI configuration of your machine. If you have problems to figure out what values for scsibus,target,lun should be used, try the -scanbus option of cdrecord.

 

OPTIONS

If no options except the dev= option have been specified, readcd goes into intercative mode. Select a primary function and then follow the instructions.

f=file
-version
Print version information and exit.
-v
Increment the level of general verbosity by one.
-V
Increment the verbose level in respect of SCSI command transport by one. This helps to debug problems during the writing process, that occur in the drive. If you get incomprehensible error messages you should use this flag to get more detailed output. -VV will show data buffer content in addition. Using -V or -VV slows down the process and may be the reason for a buffer underrun.
-w
Switch to write mode. If this option is not present, readcd reads from the specified device.
sectors=range
Specify a sector range that should be read. The range is specified by the starting sector number, a minus sign and the ending sector number.
-notrunc
Do not truncate the outputfile when opening it.

 

EXAMPLES

For all examples below, it will be assumed that the drive is connected to the primary SCSI bus of the machine. The SCSI target id is set to 2.

To read the complete media from a CD-ROM writing the data to the file cdimage.raw:


    readcd dev=2,0 f=cdimage.raw

To read sectors from range 150 ... 10000 from a CD-ROM writing the data to the file cdimage.raw:


    readcd dev=2,0 sectors=150-10000 f=cdimage.raw

To write the data from the file cdimage.raw (e.g. a filesystem image from mkisofs) to a DVD-RAM, call:


    readcd dev=2,0 -w f=cdimage.raw

 

FILES

 

SEE ALSO

cdrecord(1), mkisofs(1), scg(7), fbk(7).

 

NOTES

If you don't want to allow users to become root on your system, readcd may safely be installed suid root. This allows all users or a group of users with no root privileges to use readcd. Readcd in this case will only allow access to CD-ROM type drives- To give all user access to use readcd, enter:

       chown root /usr/local/bin/readcd

       chmod 4711 /usr/local/bin/readcd

To give a restricted group of users access to readcd enter:

       chown root /usr/local/bin/readcd

       chgrp cdburners /usr/local/bin/readcd

       chmod 4710 /usr/local/bin/readcd

and add a group cdburners on your system.

Never give write permissions for non root users to the /dev/scg? devices unless you would allow anybody to read/write/format all your disks.

You should not connect old drives that do not support disconnect/reconnect to either the SCSI bus that is connected to the CD-Recorder or the source disk.

When using readcd with the broken Linux SCSI generic driver. You should note that readcd uses a hack, that tries to emulate the functionality of the scg driver. Unfortunately, the sg driver on Linux has several severe bugs:

*
It cannot see if a SCSI command could not be sent at all.
*
It cannot get the SCSI status byte. Readcd for that reason cannot report failing SCSI commands in some situations.
*
It cannot get real DMA count of transfer. Readcd cannot tell you if there is an DMA residual count.
*
It cannot get number of bytes valid in auto sense data. Readcd cannot tell you if device transfers no sense data at all.
*
It fetches to few data in auto request sense (CCS/SCSI-2/SCSI-3 needs >= 18).

 

DIAGNOSTICS

A typical error message for a SCSI command looks like:

readcd: I/O error. test unit ready: scsi sendcmd: no error
CDB:  00 20 00 00 00 00
status: 0x2 (CHECK CONDITION)
Sense Bytes: 70 00 05 00 00 00 00 0A 00 00 00 00 25 00 00 00 00 00
Sense Key: 0x5 Illegal Request, Segment 0
Sense Code: 0x25 Qual 0x00 (logical unit not supported) Fru 0x0
Sense flags: Blk 0 (not valid)

The first line gives information about the transport of the command. The text after the first colon gives the error text for the system call from the view of the kernel. It usually is: I/O error unless other problems happen. The next words contain a short description for the SCSI command that fails. The rest of the line tells you if there were any problems for the transport of the command over the SCSI bus. fatal error means that it was not possible to transport the command (i.e. no device present at the requested SCSI address).

The second line prints the SCSI command descriptor block for the failed command.

The third line gives information on the SCSI status code returned by the command, if the transport of the command succeeds. This is error information from the SCSI device.

The fourth line is a hex dump of the auto request sense information for the command.

The fifth line is the error text for the sense key if available, followed by the segment number that is only valid if the command was a copy command. If the error message is not directly related to the current command, the text deferred error is appended.

The sixth line is the error text for the sense code and the sense qualifier if available. If the type of the device is known, the sense data is decoded from tables in scsierrs.c . The text is followed by the error value for a field replaceable unit.

The seventh line prints the block number that is related to the failed command and text for several error flags. The block number may not be valid.

 

BUGS

 

CREDITS

 

MAILING LISTS

If you want to actively take part on the development of cdrecord, you may join the cdwriting mailing list by sending mail to:

        other-cdwrite-request@lists.debian.org

and include the word subscribe in the body. The mail address of the list is:

        cdwrite@lists.debian.org

 

AUTHOR

Joerg Schilling
Seestr. 110
D-13353 Berlin
Germany

Additional information can be found on:
http://www.fokus.gmd.de/usr/schilling/cdrecord.html

Mail bugs and suggestions to:

joerg@schily.isdn.cs.tu-berlin.de or js@cs.tu-berlin.de or schilling@fokus.gmd.de


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
FILES
SEE ALSO
NOTES
DIAGNOSTICS
BUGS
CREDITS
MAILING LISTS
AUTHOR

This document was created by man2html, using the manual pages.
Time: 20:38:44 GMT, March 05, 2001