Specifications

3.Burning CD−Rs
"If to smoke you turn I shall not cease to fiddle while you burn." (Roman emperor Nero about
burning his own classic−CDs, AD64. He misunderstood it completely and burned Rome
down.)
Writing CD−ROMs consists of two steps under Linux:
• packaging the desired data (files, music or both) into files with special formats
• writing the data from the files to the CD−R with the utility cdrecord
This chapter describes the steps for data and audio CDs in greater detail.
3.1 Writing CD−ROMs (pure data)
Note that collecting the data to put onto a CD usually takes longer than one expects. Consider that missing
files cannot be added once the CD is written and fixated. This is also true for CD−RW, which can currently
only be rewritten as a whole. Using the multi−session feature is no option for single files, as it consumes
much space for a new complete table of contents (TOC). UDF is not ready yet for Linux.
Also keep in mind that a certain amount of the free space of a CD is used for storing the information of the
ISO−9660−filesystem (usually a few MB). 620 MB data will always fit on a 650 MB CD−R.
Creating an image of the later CD−ROM
Before any storage medium (e.g. floppy disk, hard disk or CD) can be used, it must get a filesystem (DOS
speak: get formatted). The filesystem is responsible for organizing and incorporating the files that should be
stored on the medium.
The usual utilities for creating filesystems on hard disk partitions write an empty filesystem onto them, which
is then mounted and filled with files by the users as they need it. A writable CD is only writable once so if we
wrote an empty filesystem to it, it would get formatted and remain completely empty forever. This is also true
for rewritable media as you cannot change arbitrary sectors yet; you must erase their whole content.
So what we need is a tool that creates the filesystem while copying the files to the CD. This tool is called
mkisofs. A sample usage looks as follows:
mkisofs −r −o cd_image private_collection/
`−−−−−−−−−' `−−−−−−−−−−−−−−−−−'
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CD−Writing HOWTO
3.Burning CD−Rs 15