Hi I have a system that gave me some messages on bootup that I was not used to seeing:
pseudo: pseudo-device: vol0
genunix: vol0 is /pseudo/vol@0
these came with these:
Feb 13 17:42:17 system1 eri: SUNW,eri0 : 100 Mbps full duplex link up
Feb 13 17:42:21 system1sendmail: My unqualified... (0 Replies)
Hi all,
what does this mean?
if
then
<something>
fi
here is what i know..
it checks if the specified argument no($devid) in some function call is made into a block device and then proceeds with the execution of the loop.
However am not understand what lofi@0:means?
also is there... (3 Replies)
I am trying to script the process of looking for a usb-key inside another application. I have gotten some success by recording "ls /dev" and comparing it to a new "ls /dev" periodically.
However this has made it so I have to prompt the user to take out the usb-key (if plugged in), let my... (1 Reply)
I am having trouble understanding the difference between a passthrough device and a named device and when you would use one or the other to access equipment.
As an example, we have a tape library and giving the command
"camcontrol devlist" gives the following output:
akx# camcontrol... (1 Reply)
Hi All,
I have putty on my system (Vista). I need some server details to login via internet for my personnel practice. Can any body help me out.
In case this not feasible, just let me know any other way to work with UNIX terminal on Windows Vista itself.
Please help me since i am desparately... (3 Replies)
I am trying to install an HP StorageWorks DAT40 Tape drive at SC0 5.0.7. The tape drive is not functional.
When I run #sconf -v this is what I get;
Sdsk ad160 0 0 0 0
Sdsk ad160 0 0 1 0
Stp ad160 0 0 3 0
But when... (2 Replies)
How can i view what my colleague is doing in the terminal pts/1 while i have logged into terminal pts/2 ?? Both have remotely logged in via ssh. (4 Replies)
Hi ,
I have searched wiki for pseudo tty devices but it was very complex for me to understand.
Can any one help me understanding concept behind pseudo-tty in layman language?
According to security manual of our org /etc/securetty files shouldn't have any pseudo tty devices.
i understand
ttyX... (5 Replies)
sometimes I see this message in dmesg:
what does it mean?
thanks. (5 Replies)
Discussion started by: orange47
5 Replies
LEARN ABOUT X11R4
raw
RAW(8) System Administration RAW(8)NAME
raw - bind a Linux raw character device
SYNOPSIS
raw /dev/raw/raw<N> <major> <minor>
raw /dev/raw/raw<N> /dev/<blockdev>
raw -q /dev/raw/raw<N>
raw -qa
DESCRIPTION
raw is used to bind a Linux raw character device to a block device. Any block device may be used: at the time of binding, the device
driver does not even have to be accessible (it may be loaded on demand as a kernel module later).
raw is used in two modes: it either sets raw device bindings, or it queries existing bindings. When setting a raw device, /dev/raw/raw<N>
is the device name of an existing raw device node in the filesystem. The block device to which it is to be bound can be specified either
in terms of its major and minor device numbers, or as a path name /dev/<blockdev> to an existing block device file.
The bindings already in existence can be queried with the -q option, which is used either with a raw device filename to query that one
device, or with the -a option to query all bound raw devices.
Unbinding can be done by specifying major and minor 0.
Once bound to a block device, a raw device can be opened, read and written, just like the block device it is bound to. However, the raw
device does not behave exactly like the block device. In particular, access to the raw device bypasses the kernel's block buffer cache
entirely: all I/O is done directly to and from the address space of the process performing the I/O. If the underlying block device driver
can support DMA, then no data copying at all is required to complete the I/O.
Because raw I/O involves direct hardware access to a process's memory, a few extra restrictions must be observed. All I/Os must be cor-
rectly aligned in memory and on disk: they must start at a sector offset on disk, they must be an exact number of sectors long, and the
data buffer in virtual memory must also be aligned to a multiple of the sector size. The sector size is 512 bytes for most devices.
OPTIONS -q, --query
Set query mode. raw will query an existing binding instead of setting a new one.
-a, --all
With -q , specify that all bound raw devices should be queried.
-h, --help
Display help text and exit.
-V, --version
Display version information and exit.
BUGS
The Linux dd(1) command should be used without the bs= option, or the blocksize needs to be a multiple of the sector size of the device
(512 bytes usually), otherwise it will fail with "Invalid Argument" messages (EINVAL).
Raw I/O devices do not maintain cache coherency with the Linux block device buffer cache. If you use raw I/O to overwrite data already in
the buffer cache, the buffer cache will no longer correspond to the contents of the actual storage device underneath. This is deliberate,
but is regarded either a bug or a feature depending on who you ask!
NOTES
Rather than using raw devices applications should prefer open(2) devices, such as /dev/sda1, with the O_DIRECT flag.
AUTHOR
Stephen Tweedie (sct@redhat.com)
AVAILABILITY
The raw command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.
util-linux August 1999 RAW(8)