12-04-2008
dd - binary file
I have a task that says: make a file (called binaryfile ) that contains
4 bytes of NULL data
6 bytes of random data
8 bytes of 1
10 bytes of 5
and 12 bytes of 9.
For the first 2, I can used :
dd if=/dev/null of=binaryfile bs=8 count =4 and
dd if=/dev/urandom of=binaryfile bs=8 count=6 seek=4, but how can I do the rest ???
I know, bs will remain 8 (8 bits) and seek will increase after each append to my file. My question is, how to tell dd what bits to copy (other than 0 or random).
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LEARN ABOUT LINUX
msgpullup
msgpullup(9F) Kernel Functions for Drivers msgpullup(9F)
NAME
msgpullup - concatenate bytes in a message
SYNOPSIS
#include <sys/stream.h>
mblk_t *msgpullup(mblk_t *mp, ssize_t len);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
mp Pointer to the message whose blocks are to be concatenated.
len Number of bytes to concatenate.
DESCRIPTION
msgpullup() concatenates and aligns the first len data bytes of the message pointed to by mp, copying the data into a new message. Any
remaining bytes in the remaining message blocks will be copied and linked onto the new message. The original message is unaltered. If len
equals -1, all data are concatenated. If len bytes of the same message type cannot be found, msgpullup() fails and returns NULL.
RETURN VALUES
msgpullup returns the following values:
Non-null Successful completion. A pointer to the new message is returned.
NULL An error occurred.
CONTEXT
msgpullup() can be called from user or interrupt context.
SEE ALSO
srv(9E), allocb(9F), pullupmsg(9F), msgb(9S)
Writing Device Drivers
STREAMS Programming Guide
NOTES
msgpullup() is a DKI-compliant replacement for the older pullupmsg(9F) routine. Users are strongly encouraged to use msgpullup() instead of
pullupmsg(9F).
SunOS 5.10 11 Nov 1996 msgpullup(9F)