UNIX for Dummies Questions & Answers

Can someone please tell me what the command mknod does and what it's syntax is? I can't find it in my "Unix for dummies" book or "Unix in s nutshell". I found it in an existing script that I want to copy, but I want to understand what I am doing. The script is going to do a full export of an Oracle database. I suspect that this command is pre-creating the output file, and making it special in some way, like giving it extra security or something, but I don't really know.

Thanks,
Beginner Bonnie

In order to use mknod you need to know the major and minor node numbers for the device you wish to create. The devices.txt file in the kernel source documentation is the canonical source of this information.

To take an example, suppose that version of the MAKEDEV script does not know how to create the /dev/ttyS0 device file. Then you need to use mknod to create it. From looking at the devices.txt file that it should be a character device with major number 4 and minor number 64. So you now know all you need to create the file.

Exp:

Code:

	# mknod /dev/ttyS0 c 4 64
	# chown root.dialout /dev/ttyS0
	# chmod 0644 /dev/ttyS0
	# ls -l /dev/ttyS0
crw-rw----   1 root dialout    4,   64 Oct 23 18:23 /dev/ttyS0

As you can see, many more steps are required to create the file. In this example you can see the process required however

That does not address my particular situation. I'm sorry, I should have included the specific code I was referring to:

rm -f pipefile
/etc/mknod pipefile p
nohup cat pipefile | /usr/contrib/bin/gzip >/oracleb/home/dba/exp/exp_full_MWOD.dmp.gz 2>/oracleb/home/dba/exp/cat_errors.log&
exp file=pipefile full=y consistent=y userid=sys/xxx log=/oracleb/home/dba/exp/exp_full_MWOD.log buffer=10000000 compress=y

Is "pipefile" something special? A device? What does the "p" indicate?

Thanks!
Beginner Bonnie

Did you try the command man mknod?