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 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-
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 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:
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,target,lun.
Scsibus 0 is the default SCSI bus on the machine. Watch the boot mes-
sages for more information or look into /var/run/dmesg.boot 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
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 /usr/local/etc/cdrecord (see FILES
section).
If no dev= option is present, or if the dev= option only con-
tains a transport specifyer but no address, readcd tries to scan
the SCSI address space for CD-ROM drives. If exactly one is
found, this is used by default.
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.
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-
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.
-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.
-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
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=#
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.
-notrunc
Do not truncate the output file when opening it.
-fulltoc
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.
-noerror
Do not abort if the high level error checking in readcd found an
uncorrectable error in the data stream.
-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.
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.
-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.
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 ouput
data created for this purpose is written to stdout.
-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.
EXAMPLES
For all examples below, it will be assumed that the drive is connected
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 /usr/local/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.
FILES
SEE ALSO
cdrecord(1), mkisofs(8), 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.
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.
cdwrite@lists.debian.org
AUTHOR
Joerg Schilling
Seestr. 110
D-13353 Berlin
Germany
Additional information can be found on:
http://www.fokus.fhg.de/usr/schilling/cdrecord.html
If you have support questions, send them to:
cdrecord-support@berlios.de
or other-cdwrite@lists.debian.org
If you have definitely found a bug, send a mail to:
cdrecord-developers@berlios.de
or schilling@fokus.fhg.de
To subscribe, use:
http://lists.berlios.de/mailman/listinfo/cdrecord-developers
or http://lists.berlios.de/mailman/listinfo/cdrecord-support
Joerg Schilling Version 2.0 READCD(1)
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