nnaammeedd ppiippee -- Definition

A _n_a_m_e_d _p_i_p_e is a special  file created with the command /eettcc/mmkknnoodd. Unlike
the block-  and character-special files  created by mmkknnoodd, a  named pipe is
not a device.

A  named  pipe  acts  like  a  conventional pipe  set  up  between  related
processes.  It differs in that it  has a visible name that can be seen in a
file system.  It also differs in that it has permissions (since it's a file
and has a name) associated with it just like any other file.  This allows a
named pipe to be accessed by  processes that are _n_o_t related to each other,
and can even be used for  processes that are running on behalf of different
users.

The following illustrates how one process  can write data into a named pipe
and an unrelated process can read from it:

     /etc/mknod my_pipe p     # create the named pipe
     chmod 644 my_pipe
     ls -lR / > my_pipe &     # pump data into pipe in background
     mail fred < my_pipe      # read from the pipe and process

This script creates  a named pipe called mmyy_ppiippee and  makes sure that it is
readable; it then  pumps a mass of data into  the pipe (in the background),
and finally  has a process read  data from the named  pipe and perform some
action  on them  (in  this case,  mail  the data  to user  ffrreedd).  In  this
example, the  mmaaiill process  could be running  from another login  and could
either be in the foreground or background.

_S_e_e _A_l_s_o
lliibbssoocckkeett, mmkkffiiffoo(), mmkknnoodd, ppiippee, UUssiinngg CCOOHHEERREENNTT
POSIX Standard, section 5.4.2
