READOM(1)

💿 READOM 💿

okay bestie, gather round, because we're about to talk about readom from the Schily´s USER COMMANDS corner of the universe and honestly? she's iconic.

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✨ NAME ✨

readom — read or write data Compact Discs 🎀

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🌸 SYNOPSIS 🌸

readom dev=device [ options ]

that's it, that's the whole vibe. one device, some options, let's go 💅

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🦋 DESCRIPTION 🦋

So like, readom is used to read or write Compact Discs. simple as that, no cap.

The device refers to a device location similar to the one used in the wodim command. bestie, go refer to its manpage for the details, i'm not gonna re-derive it for you, iykyk.

Also, huge note: this version of readom uses a modified libusal library which has a different behaviour compared to the one distributed by its original author. so if you're out here comparing notes with the O.G., don't come for me 😭 it's literally a different library.

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💖 OPTIONS 💖

okay so here's the tea: if no options except the dev= option have been specified, readom goes into interactive mode. you select a primary function and then follow the instructions. it's giving ✨choose your own adventure✨.

• -version — prints version information and exits. short, sweet, slay.
• 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 manuals 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, readom 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 interpreted as an label name that may be found in the file /etc/wodim.conf (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 command runs correctly with a raised command timeout, please report the better 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 reason for a buffer underrun. 😭 not the underrun bestie.
• kdebug=#, kd=# — Tell the usal-driver to modify the kernel debug value while SCSI commands are running. it's giving "i'm watching you at the kernel level" energy 💀
• -silent, -s — Do not print out a status report for failed SCSI commands. quiet queen behavior 👑
• -v — Increment the level of general verbosity by one. This is used e.g. to display the progress of the process. so you can actually see her working ✨
• -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 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. more tea, less speed, trade-off bestie 🍓
• 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. yes bestie, piping is real 💜
• -w — Switch to write mode. If this option is not present, readom reads from the specified device. main character decides her own destiny ✨
• -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. physics said no today 🙈

• -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 computed by: bus * 100 + target. it's a little math moment, we love to see it 🧮✨
• 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. 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. sneaky little trick, obsessed 🎀
• 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, 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. slow and steady wins the read 💅

• 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 transfer size of 256 kB. If libusal gets lower values from the operating 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. 😭 the trial-and-error arc is real.

• -notrunc — Do not truncate the output file when opening it. leave her files alone bestie 🫶
• -fulltoc — Retrieve a full TOC from the current disk and print it in hex. hex girl summer 🔥
• -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 similar name as with the f= option but the suffix .toc added. a whole duplicate, she's giving copy-paste icon 🦋
• -noerror — Do not abort if the high level error checking in readom found an uncorrectable error in the data stream. bold. fearless. risky. 💀
• -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 readom completes, the error recovery mode of the drive is switched back to the remembered old mode. she remembers where she came from, respectful queen 👑
• retries=# — 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. 128 attempts is a LOT of emotional labor ngl 😭
• -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. math girlies rise up 🧚
• meshpoints=# — Print read-speed at # locations. The purpose of this option is to create a list of read speed values suitable for e.g. gnuplot. 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. plotting girlies, this one's for you 📈✨
• -factor — Output the speed values for meshpoints=# as factor based on single speed of the current medium. This only works if readom is able to determine the current medium type. no medium type, no factor, sorry bestie 🙈

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🌈 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:

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

periodt. three little commands, infinite possibilities 💅✨

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💜 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 wodim to create a pipe to the rsh(1) program and disallows wodim 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. trade-offs, bestie 😭

• 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. sneaky detail, don't forget it 🎀

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🌸 SEE ALSO 🌸

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

go read those too, they're all part of the friend group 🫶

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⭐ NOTES ⭐

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 additional 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. so if you want the deep lore, that's where it lives 👑

bestie fr fr, run it as root or set it up suid root properly. don't just yolo it and then act surprised 💀

🩺 DIAGNOSTICS 🩺

Okay bestie, SCSI errors look scary but they're literally just a little gossip report. A typical error message for a SCSI command looks like this:

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

Let's break it down line by line, because it's giving ✨annotated edition✨:

• Line one — this is all about how the command traveled. The text after the first colon is the error text for the system call, from the kernel's point of view. It's usually I/O error unless other problems happen. Then the next words give you a short description of the SCSI command that fails. And the rest of the line tells you if there were any problems getting the command across the SCSI bus. fatal error means it was straight-up impossible to transport the command — like, no device present at the requested SCSI address. Rude.
• Line two — the SCSI command descriptor block for the failed command. Receipts. 🧾
• Line three — info on the SCSI status code the command returned, if the transport of the command succeeds. This is error tea coming straight from the SCSI device itself.
• Line four — a hex dump of the auto request sense information for the command. Very hex, very dump.
• Line five — the error text for the sense key, if it's available, followed by the segment number — and that's only valid if the command was a copy command. If the error message isn't directly related to the current command, the text deferred error gets appended. Not me getting secondhand error drama 💀
• Line six — 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. And the text is followed by the error value for a field replaceable unit.
• Line seven — the block number related to the failed command, plus text for several error flags. Heads up though: the block number may not be valid. 🙈
• Line eight — reports the timeout set up for this command, and the time that the command really needed to complete. The way it took 0.002s with a 40s timeout… main character energy honestly.

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🐛 BUGS 🐛

Okay so listen. The readom program described here is the Cdrkit spinoff from the original readcd application (peep the AUTHOR section for the details). It may contain bugs not present in the original implementation. Not a vibe, but we're being honest.

It is definitely less portable than the original implementation. Periodt.

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

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💌 MAILING LISTS 💌

If you wanna actively take part in the development of readom, you may join the developer mailing list via this URL:

http://alioth.debian.org/mail/?group_id=31006

The mail address of the list is: debburn-devel@lists.alioth.debian.org

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👑 AUTHOR 👑

Joerg Schilling Seestr. 110 D-13353 Berlin Germany

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! Like, seriously, don't. 🙅♀️

Additional information can be found on:

https://alioth.debian.org/projects/debburn/

If you have support questions, send them to

debburn-devel@lists.alioth.debian.org

If you have definitely found a bug, send a mail to this list or to

submit@bugs.debian.org

writing at least a short description into the Subject and Package: cdrkit into the first line of the mail body. (Yes bestie, the first line of the body. They're strict about it and honestly? Fair. 📝)

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📚 SOURCES 📚

• [1] Cdrtools 2.01.01a08 from May 2006, http://cdrecord.berlios.de

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And that's the whole page, bestie! 🎀 This one's from Joerg Schilling, sitting pretty at Version 2.0, and it's READOM(1) — go forth and read those discs, you absolute icon. Slay. 💅✨🦋