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READOM(1)		    Schily's USER COMMANDS		     READOM(1)

       readom -	read or	write data Compact Discs

       readom dev=device [ options ]

       Readom is used to read or write Compact Discs.

       The  device  refers to a	device location	similar	to the one used	in the
       wodim command. Refer to its manpage for details.

       Also note that this version of readom uses a modified  libusal  library
       which  has a different behaviour	compared to the	one distributed	by its
       original	author.

       If no options except the	dev= option have been specified,  readom  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, readom 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/wodim.conf (see FILES sec-

	      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 libusal.  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 usal-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 er-
	      ror messages you should use this flag to get more	detailed  out-
	      put.   -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
	      input  should  be	 taken	from. Using '-'	as filename will cause
	      readom to	use stdout resp. stdin.

       -w     Switch to	write mode. If this  option  is	 not  present,	readom
	      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 de-
	      vices  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, readom 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 wodim  fs=#  or
	      sdd bs=#.

	      If no ts=	option has been	specified, readom defaults to a	trans-
	      fer size of 256 kB. If libusal gets lower	values from the	 oper-
	      ating  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  ex-
	      perimenting 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 readom 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 readom 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 readom 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	output
	      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 readom 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

	   readom 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:

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

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

	   readom 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 wodim to create a pipe to the rsh(1) pro-
	      gram and disallows wodim to directly access the  network	socket
	      to  the  remote server.  This makes it impossible	to set up per-
	      formance 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.

       wodim(1), genisoimage(1), rcmd(3), ssh(1).

       Unless you want to risk getting problems, readom	should be run as root.
       If you don't want to allow users	to become root on your system,	readom
       may  safely be installed	suid root.  For	more information see the addi-
       tional notes of your  system/program  distribution  or  README.suidroot
       which is	part of	the Cdrkit source.

       Documentation  of  the  wodim  program  contains	more technical details
       which could also	apply to readom.

       A typical error message for a SCSI command looks	like:

	      readom: 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 er-
       ror 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.

       The readom program described here is the	Cdrkit spinoff from the	origi-
       nal readcd application (see AUTHOR section for details).	It may contain
       bugs not	present	in the original	implementation.

       It is definitely	less portable than the original	implementation.

       For platform specific bugs, see the corresponding README.platform  file
       in the Cdrkit documentation (eg.	README.linux).

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

       The mail	address	of the list is:

       Joerg Schilling
       Seestr. 110
       D-13353 Berlin

       This is application is a	spinoff	from the  original  implementation  of
       readcd	delivered  in  the  cdrtools  package  [1]  created  by	 Joerg
       Schilling, who deserves the most	credits	for its	success.  However,  he
       is  not	involved into the development of this spinoff and therefore he
       shall not be made responsible for any problem caused by it. Do not  try
       to get support from the original	author!

       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 this list or to

       writing	at  least  a  short description	into the Subject and "Package:
       cdrkit" into the	first line of the mail body.

       [1] Cdrtools 2.01.01a08 from May	2006,

Joerg Schilling			  Version 2.0			     READOM(1)


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