What does the letter »r« stand for in /dev/sr0?
James Michael Fultz
croooow at gmail.com
Thu Nov 5 18:25:50 UTC 2009
* Rashkae <ubuntu at tigershaunt.com> [2009-11-05 10:31 -0500]:
> Simply looking at the relative udev rules and comments thereof:
>
> (These are from Gutsy, there may have been changes, I'm too lazy to verify)
>
> # SCSI CD-ROM devices use /dev/scdN now
> SUBSYSTEMS=="scsi", KERNEL=="sr[0-9]*", NAME="scd%n"
>
> # Raw block devices need to be /dev/raw/*
> SUBSYSTEM=="raw", KERNEL=="raw[0-9]*", NAME="raw/%k"
>
> # Compatibility symlinks for /dev/scd* devices
> SUBSYSTEMS=="scsi", KERNEL=="sr[0-9]*", SYMLINK+="%k"
Interesting. It has changed at least as of Jaunty.
# cdrom
SUBSYSTEM=="block", KERNEL=="sr[0-9]*", SYMLINK+="scd%n", GROUP="cdrom"
Yes, according to '/usr/share/doc/udev/changelog.Debian.gz', the changed
occurred in Jaunty.
"
* Merged our rules with Upstream default rules, this results in a number
of minor changes but achieves consistency with other distributions:
[...]
* /dev/srN are now the definitive names of SCSI CD-ROM devices, with
/dev/scdN as deprecated symlinks to them; this is the exact opposite of
how we had things before.
[...]
-- Scott James Remnant <scott at ubuntu.com> Wed, 07 Jan 2009 14:01:19 +0000
"
According to the Linux Device List[1], sr? should only be
a compatibility symlink to scd?. Strange that the change reversed the
correct behavior at least according to the Linux Device List.
1. Linux Device List:
<http://www.lanana.org/docs/device-list/devices-2.6+.txt>
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