Red Hat LINUX 7.2 Reference Manual page 89

Section 4.3:Directories in /proc
or restarting a system, syncing all mounted filesystems, or dumping important information to your
console. This feature is most useful when using a development kernel or if you are experiencing
system freezes. For more information on the System Request Key, refer to /usr/src/linux-
2.4/Documentation/sysrq.txt.
A few /proc/sys configuration files contain more than one value. In order to correctly send new
values to them, place a space character between each value passed with the echo command, such as
is done in this example:
[root@bleach /]# echo "4 2 45" > /proc/sys/kernel/acct
Any configuration changes you make by echoing values into /proc/sys
files will disappear when the system is restarted. To make your configuration
changes take effect at the time the system is booted, see Section 4.4, Using
sysctl .
The /proc/sys directory contains several different directories that control different aspects of a
running kernel.
/proc/sys/dev
This directory provides parameters for particular devices on the system. Most systems have at least
two directories, cdrom and raid, but customized kernels can have others, such as parport, which
provides the ability to share one parallel port between multiple device drivers.
The cdrom directory contains a file called info, which reveals a number of important CD-ROM
parameters:
CD-ROM information, Id: cdrom.c 3.12 2000/10/18
drive name:
drive speed:
drive # of slots: 1
Can close tray:
Can open tray:
Can lock tray:
Can change speed: 1
Can select disk: 0
Can read multisession: 1
Can read MCN:
Reports media changed: 1
Can play audio:
hdc
32
1
1
1
1
1
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