02-21-2008
Your command doesn't return back control to the shell until some process reads the content of the named pipe.
After issuing that command, open another shell and type "cat myPipe": at this point the content of myPipe (that is, the content of myFile) is displayed and the first shell will return to the prompt.
About the zero size, yes, a named pipe doesn't use space on disk. Otherwise what would be the difference between a named pipe and a temporary file?
To be honest, on this point I am not totally sure, maybe googling around about this argument may clear our ideas. Or maybe some more experienced user could put light on this doubt
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PIPE(2) System Calls Manual PIPE(2)
NAME
pipe - create an interprocess communication channel
SYNOPSIS
#include <unistd.h>
int pipe(int fildes[2])
DESCRIPTION
The pipe system call creates an I/O mechanism called a pipe. The file descriptors returned can be used in read and write operations. When
the pipe is written using the descriptor fildes[1] up to PIPE_MAX bytes of data are buffered before the writing process is suspended. A
read using the descriptor fildes[0] will pick up the data.
PIPE_MAX equals 7168 under Minix, but note that most systems use 4096.
It is assumed that after the pipe has been set up, two (or more) cooperating processes (created by subsequent fork calls) will pass data
through the pipe with read and write calls.
The shell has a syntax to set up a linear array of processes connected by pipes.
Read calls on an empty pipe (no buffered data) with only one end (all write file descriptors closed) returns an end-of-file.
The signal SIGPIPE is generated if a write on a pipe with only one end is attempted.
RETURN VALUE
The function value zero is returned if the pipe was created; -1 if an error occurred.
ERRORS
The pipe call will fail if:
[EMFILE] Too many descriptors are active.
[ENFILE] The system file table is full.
[ENOSPC] The pipe file system (usually the root file system) has no free inodes.
[EFAULT] The fildes buffer is in an invalid area of the process's address space.
SEE ALSO
sh(1), read(2), write(2), fork(2).
NOTES
Writes may return ENOSPC errors if no pipe data can be buffered, because the pipe file system is full.
BUGS
Should more than PIPE_MAX bytes be necessary in any pipe among a loop of processes, deadlock will occur.
4th Berkeley Distribution August 26, 1985 PIPE(2)