DOC HOME SITE MAP MAN PAGES GNU INFO SEARCH
 

readcd(1)





NAME

       readcd - read or write data Compact Discs or related madia


SYNOPSIS

       readcd [ dev=device ][ options ]


DESCRIPTION

       Readcd is used to read or write Compact Discs.

   Device naming
       Most  users do not need to care about device naming at all.  If no dev=
       option  was  specified,  readcd  implements  auto  target  support  and
       automagically  finds  the  drive  in  case that exactly one CD-ROM type
       drive is available in the system.  In case that more  than  one  CD-ROM
       type drive exists on the system, a list of possible device name parame-
       ters may be retrieved with readcd -scanbus or from the  target  example
       from  the output of readcd dev=help, then the dev= parameter may be set
       based on the device listing.

       The device parameter to the dev= option explained below refers  to  the
       SCSI CAM standard notation for scsibus/target/lun of the CD/DVD/BluRay-
       Recorder.  If a file /etc/default/cdrecord exists, the parameter to the
       dev= option may also be a drive name label in said file (see FILES sec-
       tion).


OPTIONS

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

   Informative options
       -help  display version information for readcd on standard output.

       -version
              Print version information and exit.

       -v     Increment the level of general verbosity by one.  This  is  used
              e.g. to display the progress of the process.

   Readcd functional options
       -clone Do  a  clone  read.  Read the CD with all sub-channel data and a
              full TOC.  The full TOC data will be put into a file with  simi-
              lar name as with the f= option but the suffix .toc added.

              Note  that reading in clone mode results in having no error cor-
              rection at sub-channel level. Even in  the  main  data  channel,
              there  is less error correction than with other read modes. This
              results in a slightly quality degradation. Avoid  copying  audio
              CDs in clone mode for this reason.

       -c2scan
              Scans  the  whole CD or the range specified by the sectors=range
              for C2 errors. C2 errors are errors that are uncorrectable after
              the  second  stage  of the 24/28 + 28/32 Reed Solomon correction
              system at audio level (2352 bytes sector size). If an  audio  CD
              has  C2 errors, interpolation is needed to hide the errors. If a
              data CD has C2 errors, these errors are in most cases  corrected
              by  the  ECC/EDC  code  that  makes  2352 bytes out of 2048 data
              bytes. The ECC/EDC code should be able to correct about  100  C2
              error bytes per sector.

              If you find C2 errors you may want to reduce the speed using the
              speed= option as C2 errors may be a result of dynamic  unbalance
              on the medium.

       -cxscan
              Scans  the  whole CD or the range specified by the sectors=range
              for C1/C2/CU errors.  In non-verbose mode,  only  a  summary  is
              printed.   With  -v,  a  line  for each non error free second is
              printed.  with -vv, a line for each  second  is  printed.   This
              scan method only works for a few drives.

       -edc-corr
              In  this mode, readcd reads CD data sectors in uncorrected audio
              mode and then tries  to  correct  the  data  using  the  ECC/EDC
              decoder library from Heiko Eissfeldt. As this library implements
              looping over two layers of error correction, readcd may be  able
              to correct more data than the firmware of the CD-ROM drive.

              This  option  is currently experimental and only applicable with
              CD media and currently only supports plain 2048 Byte CD-ROM sec-
              tors.

       f=file Specify  the  filename where the output should be written or the
              input should be taken from. Using '-'  as  filename  will  cause
              readcd to use stdout resp. stdin.

       -factor
              Output the speed values for meshpoints=# as factor based on sin-
              gle speed of the current medium.  This only works if  readcd  is
              able to determine the current medium type.

       -fulltoc
              Retrieve a full TOC from the current disk and print it in hex.

       meshpoints=#
              Print  read-speed at # locations.  The purpose of this option is
              to create a list of read speed values suitable  for  e.g.   gnu-
              plot.   The speed values are calculated assuming that 1000 bytes
              are one kilobyte as documented in the SCSI standard.  The output
              data created for this purpose is written to stdout.

       -nocorr
              Switch  the  drive  into  a mode where it ignores read errors in
              data sectors that are a result of uncorrectable  ECC/EDC  errors
              before reading.  If readcd completes, the error recovery mode of
              the drive is switched back to the remembered old mode.

       -noerror
              Do not abort if the high level error checking in readcd found an
              uncorrectable error in the data stream.

       -notrunc
              Do not truncate the output file when opening it.

       -overhead
              Meter the SCSI command overhead time.  This is done by executing
              several commands 1000 times and printing the total time used. If
              you  divide  the  displayed  times  by 1000, you get the average
              overhead time for a single command.

       -pi8scan
              Scans the whole DVD or the range specified by the  sectors=range
              for  pisum8  errors.   In  non-verbose  mode,  only a summary is
              printed.  With -v, a line for each non error free block of  8  *
              32  kB is printed.  with -vv, a line for each block of 8 * 32 kB
              is printed.  This scan method only works for a few drives.

       -pifscan
              Scans the whole DVD or the range specified by the  sectors=range
              for pif errors.  In non-verbose mode, only a summary is printed.
              With -v, a line for each non  error  free  block  of  32  kB  is
              printed.   with  -vv, a line for each block of 32 kB is printed.
              This scan method only works for a few drives.

       -plot  This option modified the  behavior  for  -cxscan,  -pi8scan  and
              -pifscan.  The output is better suited for gnuplot.

       retries=#
              Set  the retry count for high level retries in readcd to #.  The
              default is to do 128 retries which may be too much if  you  like
              to read a CD with many unreadable sectors.

       sectors=range
              Specify a sector range that should be read.  The range is speci-
              fied by the starting sector number, a minus sign and the  ending
              sector  number.   The end sector is not included in the list, so
              sectors=0-0 will not read anything and may be used to check  for
              a CD in the drive.

       speed=#
              Set the speed factor of the read or write process to #.  # is an
              integer, representing a multiple of the audio  speed.   This  is
              about  150  KB/s for CD-ROM and about 172 KB/s for CD-Audio.  If
              no speed option is present, readcd will use maximum speed.  Only
              MMC  compliant  drives will benefit from this option.  The speed
              of non MMC drives is not changed.

              Using a lower speed may increase the readability of a CD or DVD.

       -w     Switch  to  write  mode.   Writing  is  only possible to DVD-RAM
              media.  For  other  media,  use  cdrecord  instead.   Note  that
              cdrecord also supports to write DVD-RAM media.

              If  this  option is not present, readcd reads from the specified
              device.

   SCSI options
       dev=target
              Set the SCSI target for the  CD/DVD/BluRay-Recorder,  see  notes
              above.  A typical target device specification is dev=1,6,0 .  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  spe-
              cific manuals of the target operating system.  On a FreeBSD sys-
              tem 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:@ .

            General SCSI addressing
              The target device to the dev=  option  refers  to  the  SCSI CAM
              standard  notation  for scsibus/target/lun of the CD/DVD/BluRay-
              Recorder. Communication 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=  scsibus,tar-
              get,lun or dev= target,lun.  In the latter case, the CD/DVD/Blu-
              Ray-Recorder 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= devicename: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 shorthand in the form dev= devicename:@ or dev= devi-
              cename:@,lun may be used instead of dev= devicename:scsibus,tar-
              get,lun.

            Remote SCSI addressing
              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.
              In order to allow remote access to a specific host, the rscsi(1)
              program needs to be present and configured on the host.

            Alternate SCSI transports
              Cdrecord is completely based on SCSI commands  but  this  is  no
              problem as all CD/DVD/BluRay writers ever made use SCSI commands
              for the communication. Even ATAPI drives are  just  SCSI  drives
              that  inherently  use  the  ATA packet interface as SCSI command
              transport layer build into the IDE  (ATA)  transport.   You  may
              need  to  specify  an  alternate  transport layer on the command
              line if your OS does not implement  a  fully  integrated  kernel
              driver subsystem that allows to access any drive using SCSI com-
              mands via a single unique user interface.

              To access SCSI devices via alternate transport layers, you  need
              to  prepend the SCSI device name by a transport layer indicator.
              The transport layer indicator may be something  like  USCSI:  or
              ATAPI:.   To  get  a list of supported transport layers for your
              platform, use dev= HELP:

            Portability Background
              To make readcd portable to all UNIX platforms, the  syntax  dev=
              devicename:scsibus,target,lun  is  preferred as it hides OS spe-
              cific knowledge about device names from the user.  A specific OS
              may  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,tar-
              get,lun should be  used,  try  the  -scanbus  option  of  readcd
              described below.

            Using logical names for devices
              If  no  dev option is present, readcd will try to get the device
              from the CDR_DEVICE environment.

              If a file /etc/default/cdrecord exists, and if the  argument  to
              the  dev=  option or the CDR_DEVICE environment does not contain
              the characters ',', '/', '@' or ':',  it  is  interpreted  as  a
              device    label    name   that   was   defined   in   the   file
              /etc/default/cdrecord (see FILES section).

            Autotarget Mode
              If no dev= option and no CDR_DEVICE environment is  present,  or
              if  it  only contains a transport specifyer but no address nota-
              tion, readcd tries to scan the SCSI  address  space  for  CD-ROM
              drives.  If exactly one is found, this is used by default.

       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 rea-
              son for a buffer underrun.

       kdebug=#, kd=#
              Tell the scg-driver to modify the kernel debug value while  SCSI
              commands are running.

       -scanbus
              Scan  all  SCSI devices on all SCSI busses and print the inquiry
              strings. This option may be used to find  SCSI  address  of  the
              devices on a system.  The numbers printed out as labels are com-
              puted by: bus * 100 + target

       scgopts=list
              A comma separated list of SCSI options that are handled by  lib-
              scg.   The implemented options may be uptated indepentendly from
              applications.  Currently, one option: ignore-resid is  supported
              to work around a Linux kernel bug.

       -silent, -s
              Do not print out a status report for failed SCSI commands.

       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 time-
              out, you may try to raise the default SCSI command timeout above
              the  timeout  value  of the failed command.  If the command runs
              correctly with a raised command timeout, please report the  bet-
              ter timeout value and the corresponding command to the author of
              the program.  If no timeout option is present, a default timeout
              of 40 seconds is used.

       ts=#   Set  the  maximum  transfer size for a single SCSI command to #.
              The syntax for the ts= option is the same as for  cdrecord  fs=#
              or sdd bs=#.

              If no ts= option has been specified, readcd defaults to a trans-
              fer size of 256 kB. If libscg gets lower values from the operat-
              ing  system,  the  value is reduced to the maximum value that is
              possible with the current operating system.  Sometimes,  it  may
              help  to  further reduce the transfer size or to enhance it, but
              note that it may take a long time to  find  a  better  value  by
              experimenting with the ts= option.

       -V     Increment  the verbose level with respect of SCSI command trans-
              port by one.  This helps to debug problems during  the  process,
              that  occur  in  the  CD-Recorder.   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.


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


ENVIRONMENT

       RSH    If  the  RSH  environment is present, the remote connection will
              not be created via rcmd(3) but by calling the program pointed to
              by  RSH.   Use  e.g.   RSH=/usr/bin/ssh to create a secure shell
              connection.

              Note that this forces cdrecord to create a pipe  to  the  rsh(1)
              program  and  disallows  cdrecord to directly access the network
              socket to the remote server.  This makes it impossible to set up
              performance parameters and slows down the connection compared to
              a root initiated rcmd(3) connection.

       RSCSI  If the RSCSI environment is present, the remote SCSI server will
              not  be  the  program  /opt/schily/sbin/rscsi  but  the  program
              pointed to by RSCSI.  Note that the remote SCSI  server  program
              name  will  be  ignored  if you log in using an account that has
              been created with a remote SCSI server program as login shell.


EXIT STATUS

       The following exit codes are used:

       0      No error appeared.

       -1     A specific error appeared. This may be a usage error  caused  by
              an illegal command line or another error with a problem specific
              error message from readcd.

       -2     An unspecified error appeared during the process of  talking  to
              the  drive.   See  SCSI error message for more informations. The
              section DIAGNOSTICS below contains an explanation on how to read
              SCSI error messages.

       Note  that older operating systems and older shells may not support the
       full 32 bit range of the exit code and mask the value with  0xFF.  This
       results  in shortened exit codes in the range 0..255 where -1 is mapped
       to 255.


FILES


SEE ALSO

       cdrecord(1), mkisofs(8), scg(7), fbk(7), rcmd(3), ssh(1).


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/recon-
       nect to either the SCSI bus that is connected to the CD-Recorder or the
       source disk.

       When using readcd with the Linux SCSI generic driver.  You should  note
       that  readcd  uses  a layer, that tries to emulate the functionality of
       the scg driver on top of the drives  of  the  local  operating  system.
       Unfortunately, the sg driver on Linux has several flaws:

       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 can-
              not 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  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,  fol-
       lowed  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  cur-
       rent command, the text deferred error is appended.

       The sixth line is the error text for the sense code and the sense qual-
       ifier 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 command and the time
       that the command really needed to complete.


BUGS


CREDITS


MAILING LISTS

       If  you  want to actively take part on the development of cdrecord, you
       may join the developer mailing list via this URL:

       https://lists.sourceforge.net/lists/listinfo/cdrtools-developers


AUTHOR

       Joerg Schilling
       Seestr. 110
       D-13353 Berlin
       Germany

       Additional information can be found on:
       http://cdrecord.org/private/cdrecord.html

       If you have support questions, send them to:

       cdrtools-support@lists.sourceforge.net

       If you have definitely found a bug, send a mail to:

       cdrtools-developers@lists.sourceforge.net
       or joerg.schilling@fokus.fraunhofer.de

       To subscribe, use:

       https://lists.sourceforge.net/lists/listinfo/cdrtools-developers
       or https://lists.sourceforge.net/lists/listinfo/cdrtools-support


INTERFACE STABILITY

       The interfaces provided by readcd are designed for long term stability.
       As  readcd  depends  on interfaces provided by the underlying operating
       system, the stability of the interfaces offered by  readcd  depends  on
       the  interface  stability of the OS interfaces.  Modified interfaces in
       the OS may enforce modified interfaces in readcd.

Joerg Schilling             Version 3.02 2017/06/06                  READCD(1)

Man(1) output converted with man2html