I've been looking over my documentation for early versions of unix. The mknod system call and the mknod utility are restricted to root only until the arrivial of named pipes. When unix has named pipes, both the mknod system call and the mknod utility make an exception that allows anyone to create named pipes. I can't find a counter example to this, but I can accept that alan has found one.

I too am interested in which version of unix that alan is using. Alan since you are new to unix, you may not yet know about the uname command. "uname -a" is a command that will tell us about your version of unix.

As for mkfifo, both the function and utility seems to have come from posix. Originally, it seems, posix did not support mknod as being too unix-like. But it looks like mknod is there now, so i guess that they got over it.

Now concerning this:

[dev1@la]/home/dev1% echo "hello world" > bla
ksh: bla: cannot create

Before ksh can run the echo command, it must open bla. I would interpret this as ksh decided that it must create "bla" and was not succeeding. That would be very odd since the preceding "cat bla" seems to have worked.

alan, since mknod was not working for you, why did you use it in the example you posted? Were you running as root? Did you try the mkfifo command instead? Also after you create bla, run the command "ls -l bla" and post the results of that.