READCD(D) Schily's USER COMMANDS READCD(D) 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. Com- munication on SunOS is done with the SCSI general driver scg. Other operating systems are using a library simula- tion of this driver. Possible syntax is: dev= scsi- bus,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 correct syntax for the device is: dev= device- name:scsibus,target,lun or dev= devicename:target,lun. If the name of the device node that has been specified on such a system refers to exactly one SCSI device, a short- hand in the form dev= devicename:@ or dev= device- name:@,lun may be used instead of dev= devicename:scsi- bus,target,lun. To access remote SCSI devices, you need to prepend the SCSI device name by a remote device indicator. The remote device indicator is either REMOTE:user@host: or REMOTE:host: A valid remote SCSI device name may be: REMOTE:user@host: to allow remote SCSI bus scanning or REMOTE:user@host:1,0,0 to access the SCSI device at host connected to SCSI bus # 1,target 0 lun 0. 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 scsi- bus,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 con- figuration of your machine. If you have problems to fig- ure 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 func- tion and then follow the instructions. -version Print version information and exit. dev=target Sets the SCSI target for the drive, see notes above. A typical device specification is dev=6,0 . If a filename must be provided together with the numerical target specification, the filename is implementation specific. The correct filename in this case can be found in the system specific manu- als of the target operating system. On a FreeBSD system without CAM support, you need to use the control device (e.g. /dev/rcd0.ctl). A correct device specification in this case may be dev=/dev/rcd0.ctl:@ . On Linux, drives connected to a parallel port adapter are mapped to a virtual SCSI bus. Different adapters are mapped to different targets on this virtual SCSI bus. If no dev option is present, cdrecord will try to get the device from the CDR_DEVICE environment. If the argument to the dev= option does not contain the characters ',', '/', '@' or ':', it is inter- preted as an label name that may be found in the file /etc/default/cdrecord (see FILES section). timeout=# Set the default SCSI command timeout value to # seconds. The default SCSI command timeout is the minimum timeout used for sending SCSI commands. If a SCSI command fails due to a timeout, you may try to raise the default SCSI command timeout above the timeout value of the failed command. If the com- mand runs correctly with a raised command timeout, please report the better timeout value and the cor- responding command to the author of the program. If no timeout option is present, a default timeout of 40 seconds is used. debug=#, -d Set the misc debug value to # (with debug=#) or increment the misc debug level by one (with -d). If you specify -dd, this equals to debug=2. This may help to find problems while opening a driver for libscg. as well as with sector sizes and sector types. Using -debug slows down the process and may be the reason for a buffer underrun. kdebug=#, kd=# Tell the scg-driver to modify the kernel debug value while SCSI commands are running. -silent, -s Do not print out a status report for failed SCSI commands. -v Increment the level of general verbosity by one. This is used e.g. to display the progress of the process. -V Increment the verbose level with respect of SCSI command transport by one. This helps to debug problems during the process, that occur in the CD- Recorder. If you get incomprehensible error mes- sages you should use this flag to get more detailed output. -VV will show data buffer content in addi- tion. Using -V or -VV slows down the process. f=file -w Switch to write mode. If this option is not pre- sent, 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(d), mkisofs(s), scg(g), fbk(k). 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 privi- leges 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 dis- connect/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: o It cannot see if a SCSI command could not be sent at all. o It cannot get the SCSI status byte. Readcd for that reason cannot report failing SCSI commands in some situations. o It cannot get real DMA count of transfer. Readcd cannot tell you if there is an DMA residual count. o It cannot get number of bytes valid in auto sense data. Readcd cannot tell you if device transfers no sense data at all. o 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) cmd finished after 0.002s timeout 40s 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 ker- nel. It usually is: I/O error unless other problems hap- pen. 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 pos- sible 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 mes- sage 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. The eight line reports the timeout set up for this commans and the time that the command realy needed to be finished. BUGS CREDITS MAILING LISTS If you want to actively take part on the development of cdrecord, you may join the cdwriting mailing list by send- ing 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 If you have support questions, send them to: cdrecord-support@berlios.de or other-cdwrite@lists.debian.org Of you definitly found a bug, send a mail to: cdrecord-developers@berlios.de or schilling@fokus.gmd.de To subscribe, use: http://lists.berlios.de/mailman/listinfo/cdrecord-develop- ers or http://lists.berlios.de/mailman/listinfo/cdrecord-sup- port Joerg Schilling Version 1.10 READCD(D)