readcd man page on JazzOS

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READCD(1)		    Schily´s USER COMMANDS		     READCD(1)

       readcd - read or write data Compact Discs

       readcd dev=device [ options ]

       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  sys‐
       tems  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 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= devicename:@,lun may be used instead of	dev=  devicename:scsi‐

       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  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=

       To  make readcd portable to all UNIX platforms, the syntax dev= device‐
       name: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	0  is the default SCSI bus on the machine. Watch the boot mes‐
       sages 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.

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

	      Print version information and exit.

	      Sets  the SCSI target for the drive, see notes above.  A typical
	      device specification is dev=6,0 .	 If a filename	must  be  pro‐
	      vided  together  with  the  numerical  target specification, the
	      filename is implementation specific.  The	 correct  filename  in
	      this  case  can  be  found in the system specific manuals of the
	      target operating system.	On a FreeBSD system without  CAM  sup‐
	      port,  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  differ‐
	      ent 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  charac‐
	      ters  ',',  '/',	'@' or ':', it is interpreted as an label name
	      that may be found in the file /etc/default/cdrecord  (see	 FILES

	      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.

       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.

       -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	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.

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

       -w     Switch  to  write	 mode.	If  this option is not present, readcd
	      reads from the specified device.

	      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.

	      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

	      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.

	      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.

       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  maimum  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.

	      Do not truncate the output file when opening it.

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

       -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.

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

	      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.

	      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.

	      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.

	      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	 ouput
	      data created for this purpose is written to stdout.

	      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.

       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

	   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

       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

	      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.

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

       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

       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  broken  Linux  SCSI	generic	 driver.   You
       should  note  that  readcd uses a hack, that tries to emulate the func‐
       tionality 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 can‐
	      not 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).

       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

       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

       The eight line reports the timeout set up for this command and the time
       that the command really needed to complete.

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

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

       Joerg Schilling
       Seestr. 110
       D-13353 Berlin

       Additional information can be found on:

       If you have support questions, send them to:

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

       To subscribe, use:

Joerg Schilling			  Version 2.0			     READCD(1)

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